diff --git a/algebricks/algebricks-core/pom.xml b/algebricks/algebricks-core/pom.xml
new file mode 100644
index 0000000..84e400e
--- /dev/null
+++ b/algebricks/algebricks-core/pom.xml
@@ -0,0 +1,51 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <artifactId>algebricks-core</artifactId>
+
+  <parent>
+    <groupId>edu.uci.ics.hyracks</groupId>
+    <artifactId>algebricks</artifactId>
+    <version>0.2.2-SNAPSHOT</version>
+  </parent>
+
+  <build>
+    <plugins>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-compiler-plugin</artifactId>
+        <version>2.0.2</version>
+        <configuration>
+          <source>1.6</source>
+          <target>1.6</target>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+  <dependencies>
+  <dependency>
+  	<groupId>edu.uci.ics.hyracks</groupId>
+  	<artifactId>hyracks-storage-am-btree</artifactId>
+  	<version>0.2.2-SNAPSHOT</version>
+  </dependency>
+  <dependency>
+  	<groupId>edu.uci.ics.hyracks</groupId>
+  	<artifactId>hyracks-storage-am-rtree</artifactId>
+  	<version>0.2.2-SNAPSHOT</version>
+  </dependency>
+  <dependency>
+  	<groupId>edu.uci.ics.hyracks</groupId>
+  	<artifactId>hyracks-dataflow-std</artifactId>
+  	<version>0.2.2-SNAPSHOT</version>
+  </dependency>
+  <dependency>
+  	<groupId>edu.uci.ics.hyracks</groupId>
+  	<artifactId>algebricks-runtime</artifactId>
+  	<version>0.2.2-SNAPSHOT</version>
+  </dependency>
+  <dependency>
+  	<groupId>edu.uci.ics.hyracks</groupId>
+  	<artifactId>algebricks-common</artifactId>
+  	<version>0.2.2-SNAPSHOT</version>
+  </dependency>
+  </dependencies>
+</project>
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/Counter.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/Counter.java
new file mode 100644
index 0000000..b27bf84
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/Counter.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+public class Counter {
+    private int counter = 0;
+
+    public Counter() {
+    }
+
+    public Counter(int initial) {
+        counter = initial;
+    }
+
+    public int get() {
+        return counter;
+    }
+
+    public void inc() {
+        ++counter;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/EquivalenceClass.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/EquivalenceClass.java
new file mode 100644
index 0000000..fe3511e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/EquivalenceClass.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public final class EquivalenceClass {
+    private List<LogicalVariable> members;
+    private ILogicalExpression constRepresentative;
+    private LogicalVariable variableRepresentative;
+    private boolean representativeIsConst;
+
+    public EquivalenceClass(List<LogicalVariable> members, ILogicalExpression constRepresentative) {
+        this.members = members;
+        this.constRepresentative = constRepresentative;
+        representativeIsConst = true;
+    }
+
+    public EquivalenceClass(List<LogicalVariable> members, LogicalVariable variableRepresentative) {
+        this.members = members;
+        this.variableRepresentative = variableRepresentative;
+        representativeIsConst = false;
+    }
+
+    public boolean representativeIsConst() {
+        return representativeIsConst;
+    }
+
+    public List<LogicalVariable> getMembers() {
+        return members;
+    }
+
+    public boolean contains(LogicalVariable var) {
+        return members.contains(var);
+    }
+
+    public ILogicalExpression getConstRepresentative() {
+        return constRepresentative;
+    }
+
+    public LogicalVariable getVariableRepresentative() {
+        return variableRepresentative;
+    }
+
+    public void setConstRepresentative(ILogicalExpression constRepresentative) {
+        this.constRepresentative = constRepresentative;
+        this.representativeIsConst = true;
+    }
+
+    public void setVariableRepresentative(LogicalVariable variableRepresentative) {
+        this.variableRepresentative = variableRepresentative;
+        this.representativeIsConst = false;
+    }
+
+    public void merge(EquivalenceClass ec2) {
+        members.addAll(ec2.getMembers());
+        if (!representativeIsConst && ec2.representativeIsConst()) {
+            representativeIsConst = true;
+            constRepresentative = ec2.getConstRepresentative();
+        }
+    }
+
+    public void addMember(LogicalVariable v) {
+        members.add(v);
+    }
+
+    public EquivalenceClass cloneEquivalenceClass() {
+        List<LogicalVariable> membersClone = new LinkedList<LogicalVariable>();
+        membersClone.addAll(members);
+        EquivalenceClass ec;
+        if (representativeIsConst()) {
+            ec = new EquivalenceClass(membersClone, constRepresentative);
+        } else {
+            ec = new EquivalenceClass(membersClone, variableRepresentative);
+        }
+        return ec;
+    }
+
+    @Override
+    public String toString() {
+        return "(<" + (representativeIsConst ? constRepresentative : variableRepresentative) + "> " + members + ")";
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof EquivalenceClass)) {
+            return false;
+        } else {
+            EquivalenceClass ec = (EquivalenceClass) obj;
+            if (!members.equals(ec.getMembers())) {
+                return false;
+            }
+            if (representativeIsConst) {
+                return ec.representativeIsConst() && (constRepresentative.equals(ec.getConstRepresentative()));
+            } else {
+                return !ec.representativeIsConst() && (variableRepresentative.equals(ec.getVariableRepresentative()));
+            }
+        }
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IHyracksJobBuilder.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IHyracksJobBuilder.java
new file mode 100644
index 0000000..4c6e747
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IHyracksJobBuilder.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IPushRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public interface IHyracksJobBuilder {
+    public enum TargetConstraint {
+        ONE,
+        SAME_COUNT
+    }
+
+    public void contributeHyracksOperator(ILogicalOperator op, IOperatorDescriptor opDesc);
+
+    public void contributeAlgebricksPartitionConstraint(IOperatorDescriptor opDesc, AlgebricksPartitionConstraint apc);
+
+    public void contributeMicroOperator(ILogicalOperator op, IPushRuntimeFactory runtime, RecordDescriptor recDesc);
+
+    public void contributeMicroOperator(ILogicalOperator op, IPushRuntimeFactory runtime, RecordDescriptor recDesc,
+            AlgebricksPartitionConstraint pc);
+
+    /**
+     * inputs are numbered starting from 0
+     */
+    public void contributeGraphEdge(ILogicalOperator src, int srcOutputIndex, ILogicalOperator dest, int destInputIndex);
+
+    public void contributeConnector(ILogicalOperator exchgOp, IConnectorDescriptor conn);
+
+    public void contributeConnectorWithTargetConstraint(ILogicalOperator exchgOp, IConnectorDescriptor conn,
+            TargetConstraint numberOfTargetPartitions);
+
+    public JobSpecification getJobSpec();
+
+    /**
+     * to be called only after all the graph information is added
+     */
+    public void buildSpec(List<ILogicalOperator> roots) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalExpression.java
new file mode 100644
index 0000000..b1a2408
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalExpression.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public interface ILogicalExpression {
+
+    public LogicalExpressionTag getExpressionTag();
+
+    public abstract <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException;
+
+    public void getUsedVariables(Collection<LogicalVariable> vars);
+
+    public void substituteVar(LogicalVariable v1, LogicalVariable v2);
+
+    // constraints (e.g., FDs, equivalences)
+
+    /**
+     * @param fds
+     *            Output argument: functional dependencies that can be inferred
+     *            from this expression.
+     * @param equivClasses
+     *            Output argument: Equivalence classes that can be inferred from
+     *            this expression.
+     */
+    public void getConstraintsAndEquivClasses(Collection<FunctionalDependency> fds,
+            Map<LogicalVariable, EquivalenceClass> equivClasses);
+
+    /**
+     * @param fds
+     *            Output argument: functional dependencies that can be inferred
+     *            from this expression.
+     * @param outerVars
+     *            Input argument: variables coming from outer branch(es), e.g.,
+     *            the left branch of a left outer join.
+     */
+    public void getConstraintsForOuterJoin(Collection<FunctionalDependency> fds, Collection<LogicalVariable> outerVars);
+
+    /**
+     * @param conjs
+     *            Output argument: a list of expression whose conjunction, in
+     *            any order, can replace the current expression.
+     * @return true if the expression can be broken in at least two conjuncts,
+     *         false otherwise.
+     */
+    public boolean splitIntoConjuncts(List<Mutable<ILogicalExpression>> conjs);
+
+    public abstract ILogicalExpression cloneExpression();
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java
new file mode 100644
index 0000000..165fccd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+
+public interface ILogicalOperator {
+
+    public List<Mutable<ILogicalOperator>> getInputs();
+
+    boolean hasInputs();
+
+    public void recomputeSchema() throws AlgebricksException;
+
+    public List<LogicalVariable> getSchema();
+
+    /*
+     * 
+     * support for visitors
+     */
+
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException;
+
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException;
+
+    public boolean isMap();
+
+    public Map<String, Object> getAnnotations();
+
+    public void removeAnnotation(String annotationName);
+
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException;
+
+    // variables
+
+    /**
+     * Get the variable propogation policy from this operator's input to its
+     * output.
+     * 
+     * @return The VariablePropogationPolicy.
+     */
+    public VariablePropagationPolicy getVariablePropagationPolicy();
+
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException;
+
+    public IVariableTypeEnvironment computeInputTypeEnvironment(ITypingContext ctx) throws AlgebricksException;
+
+    // structural properties
+
+    /**
+     * @return for each child, one vector of required physical properties
+     */
+
+    public PhysicalRequirements getRequiredPhysicalPropertiesForChildren(IPhysicalPropertiesVector requiredProperties);
+
+    /**
+     * @return the physical properties that this operator delivers, based on
+     *         what its children deliver
+     */
+
+    public IPhysicalPropertiesVector getDeliveredPhysicalProperties();
+
+    public void computeDeliveredPhysicalProperties(IOptimizationContext context) throws AlgebricksException;
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlan.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlan.java
new file mode 100644
index 0000000..c94a9c1
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlan.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+public interface ILogicalPlan {
+    public List<Mutable<ILogicalOperator>> getRoots();
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlanAndMetadata.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlanAndMetadata.java
new file mode 100644
index 0000000..1d354de
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalPlanAndMetadata.java
@@ -0,0 +1,26 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public interface ILogicalPlanAndMetadata {
+    public ILogicalPlan getPlan();
+
+    public IMetadataProvider<?, ?> getMetadataProvider();
+
+    public AlgebricksPartitionConstraint getClusterLocations();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java
new file mode 100644
index 0000000..468d25c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java
@@ -0,0 +1,88 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionEvalSizeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IMergeAggregationExpressionFactory;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableEvalSizeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILogicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.PhysicalOptimizationConfig;
+
+public interface IOptimizationContext extends ITypingContext {
+
+    public abstract int getVarCounter();
+
+    // -1 if unknown
+    public abstract int getFrameSize();
+
+    public abstract void setVarCounter(int varCounter);
+
+    public abstract LogicalVariable newVar();
+
+    public abstract IMetadataProvider<?, ?> getMetadataProvider();
+
+    public abstract void setMetadataDeclarations(IMetadataProvider<?, ?> metadataProvider);
+
+    public abstract boolean checkIfInDontApplySet(IAlgebraicRewriteRule rule, ILogicalOperator op);
+
+    public abstract void addToDontApplySet(IAlgebraicRewriteRule rule, ILogicalOperator op);
+
+    /*
+     * returns true if op1 and op2 have already been compared
+     */
+    public abstract boolean checkAndAddToAlreadyCompared(ILogicalOperator op1, ILogicalOperator op2);
+
+    public abstract void addNotToBeInlinedVar(LogicalVariable var);
+
+    public abstract boolean shouldNotBeInlined(LogicalVariable var);
+
+    public abstract void addPrimaryKey(FunctionalDependency pk);
+
+    public abstract List<LogicalVariable> findPrimaryKey(LogicalVariable recordVar);
+
+    public abstract void putEquivalenceClassMap(ILogicalOperator op, Map<LogicalVariable, EquivalenceClass> eqClassMap);
+
+    public abstract Map<LogicalVariable, EquivalenceClass> getEquivalenceClassMap(ILogicalOperator op);
+
+    public abstract void putFDList(ILogicalOperator op, List<FunctionalDependency> fdList);
+
+    public abstract List<FunctionalDependency> getFDList(ILogicalOperator op);
+
+    public abstract void putLogicalPropertiesVector(ILogicalOperator op, ILogicalPropertiesVector v);
+
+    public abstract ILogicalPropertiesVector getLogicalPropertiesVector(ILogicalOperator op);
+
+    public abstract IExpressionEvalSizeComputer getExpressionEvalSizeComputer();
+
+    public abstract IVariableEvalSizeEnvironment getVariableEvalSizeEnvironment();
+
+    public abstract IMergeAggregationExpressionFactory getMergeAggregationExpressionFactory();
+
+    public abstract PhysicalOptimizationConfig getPhysicalOptimizationConfig();
+
+    public abstract void invalidateTypeEnvironmentForOperator(ILogicalOperator op);
+
+    public abstract void computeAndSetTypeEnvironmentForOperator(ILogicalOperator op) throws AlgebricksException;
+
+    public abstract void updatePrimaryKeys(Map<LogicalVariable, LogicalVariable> mappedVars);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IPhysicalOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IPhysicalOperator.java
new file mode 100644
index 0000000..58c2870
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IPhysicalOperator.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+
+public interface IPhysicalOperator {
+
+    public PhysicalOperatorTag getOperatorTag();
+
+    /**
+     * @param op
+     *            the logical operator this physical operator annotates
+     * @param reqdByParent
+     *            parent's requirements, which are not enforced for now, as we
+     *            only explore one plan
+     * @return for each child, one vector of required physical properties
+     */
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent);
+
+    /**
+     * @return the physical properties that this operator delivers, based on
+     *         what its children deliver
+     */
+    public IPhysicalPropertiesVector getDeliveredProperties();
+
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException;
+
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException;
+
+    public void disableJobGenBelowMe();
+
+    public boolean isJobGenDisabledBelowMe();
+
+    public boolean isMicroOperator();
+
+    public void setHostQueryContext(Object context);
+
+    public Object getHostQueryContext();
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalExpressionTag.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalExpressionTag.java
new file mode 100644
index 0000000..166b357
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalExpressionTag.java
@@ -0,0 +1,19 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+public enum LogicalExpressionTag {
+    FUNCTION_CALL, VARIABLE, CONSTANT
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java
new file mode 100644
index 0000000..5234d2c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+public enum LogicalOperatorTag {
+    AGGREGATE,
+    ASSIGN,
+    CLUSTER,
+    DATASOURCESCAN,
+    DISTINCT,
+    GROUP,
+    EMPTYTUPLESOURCE,
+    EXCHANGE,
+    INNERJOIN,
+    LEFTOUTERJOIN,
+    LIMIT,
+    DIE,
+    NESTEDTUPLESOURCE,
+    ORDER,
+    PROJECT,
+    PARTITIONINGSPLIT,
+    REPLICATE,
+    RUNNINGAGGREGATE,
+    SCRIPT,
+    SELECT,
+    SINK,
+    SUBPLAN,
+    UNIONALL,
+    UNNEST,
+    UNNEST_MAP,
+    WRITE,
+    WRITE_RESULT,
+    INSERT_DELETE,
+    INDEX_INSERT_DELETE,
+    UPDATE,
+    EXTENSION_OPERATOR
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalVariable.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalVariable.java
new file mode 100644
index 0000000..0a88459
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalVariable.java
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+/**
+ * Represents a logical variable in an asterix logical plan.
+ * 
+ * @author Vinayak R. Borkar [vborkar@ics.uci.edu]
+ */
+public final class LogicalVariable {
+    private final int id;
+
+    public LogicalVariable(int id) {
+        this.id = id;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    @Override
+    public String toString() {
+        return "$$" + id;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof LogicalVariable)) {
+            return false;
+        } else {
+            return id == ((LogicalVariable) obj).getId();
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        return id;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/OperatorAnnotations.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/OperatorAnnotations.java
new file mode 100644
index 0000000..655645f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/OperatorAnnotations.java
@@ -0,0 +1,12 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+public interface OperatorAnnotations {
+    // hints
+    public static final String USE_HASH_GROUP_BY = "USE_HASH_GROUP_BY"; // -->
+    public static final String USE_EXTERNAL_GROUP_BY = "USE_EXTERNAL_GROUP_BY"; // -->
+    // Boolean
+    public static final String CARDINALITY = "CARDINALITY"; // -->
+    // Integer
+    public static final String MAX_NUMBER_FRAMES = "MAX_NUMBER_FRAMES"; // -->
+    // Integer
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java
new file mode 100644
index 0000000..a969372
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java
@@ -0,0 +1,48 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.base;
+
+public enum PhysicalOperatorTag {
+    AGGREGATE,
+    ASSIGN,
+    BROADCAST_EXCHANGE,
+    BTREE_SEARCH,
+    STATS,
+    DATASOURCE_SCAN,
+    EMPTY_TUPLE_SOURCE,
+    EXTERNAL_GROUP_BY,
+    IN_MEMORY_HASH_JOIN,
+    HASH_GROUP_BY,
+    HASH_PARTITION_EXCHANGE,
+    HASH_PARTITION_MERGE_EXCHANGE,
+    HYBRID_HASH_JOIN,
+    HDFS_READER,
+    IN_MEMORY_STABLE_SORT,
+    MICRO_PRE_CLUSTERED_GROUP_BY,
+    NESTED_LOOP,
+    NESTED_TUPLE_SOURCE,
+    ONE_TO_ONE_EXCHANGE,
+    PRE_SORTED_DISTINCT_BY,
+    PRE_CLUSTERED_GROUP_BY,
+    RANGE_PARTITION_EXCHANGE,
+    RANDOM_MERGE_EXCHANGE,
+    RTREE_SEARCH,
+    RUNNING_AGGREGATE,
+    SORT_MERGE_EXCHANGE,
+    SINK,
+    SINK_WRITE,
+    SPLIT,
+    STABLE_SORT,
+    STREAM_LIMIT,
+    STREAM_DIE,
+    STREAM_SELECT,
+    STREAM_PROJECT,
+    STRING_STREAM_SCRIPT,
+    SUBPLAN,
+    UNION_ALL,
+    UNNEST,
+    WRITE_RESULT,
+    INSERT_DELETE,
+    INDEX_INSERT_DELETE,
+	UPDATE,
+    INVERTED_INDEX_SEARCH,
+    PARTITIONINGSPLIT
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractFunctionCallExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractFunctionCallExpression.java
new file mode 100644
index 0000000..0d9e763
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractFunctionCallExpression.java
@@ -0,0 +1,326 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+
+public abstract class AbstractFunctionCallExpression extends AbstractLogicalExpression {
+
+    public enum FunctionKind {
+        SCALAR,
+        STATEFUL,
+        AGGREGATE,
+        UNNEST
+    }
+
+    protected IFunctionInfo finfo;
+    final private List<Mutable<ILogicalExpression>> arguments;
+    private Object[] opaqueParameters;
+    private final FunctionKind kind;
+    private Map<Object, IExpressionAnnotation> annotationMap = new HashMap<Object, IExpressionAnnotation>();
+
+    public AbstractFunctionCallExpression(FunctionKind kind, IFunctionInfo finfo,
+            List<Mutable<ILogicalExpression>> arguments) {
+        this.kind = kind;
+        this.finfo = finfo;
+        this.arguments = arguments;
+    }
+
+    public AbstractFunctionCallExpression(FunctionKind kind, IFunctionInfo finfo) {
+        this.kind = kind;
+        this.finfo = finfo;
+        this.arguments = new ArrayList<Mutable<ILogicalExpression>>();
+    }
+
+    public AbstractFunctionCallExpression(FunctionKind kind, IFunctionInfo finfo,
+            Mutable<ILogicalExpression>... expressions) {
+        this(kind, finfo);
+        for (Mutable<ILogicalExpression> e : expressions) {
+            this.arguments.add(e);
+        }
+    }
+
+    public void setOpaqueParameters(Object[] opaqueParameters) {
+        this.opaqueParameters = opaqueParameters;
+    }
+
+    public Object[] getOpaqueParameters() {
+        return opaqueParameters;
+    }
+
+    public FunctionKind getKind() {
+        return kind;
+    }
+
+    protected List<Mutable<ILogicalExpression>> cloneArguments() {
+        List<Mutable<ILogicalExpression>> clonedArgs = new ArrayList<Mutable<ILogicalExpression>>(arguments.size());
+        for (Mutable<ILogicalExpression> e : arguments) {
+            ILogicalExpression e2 = ((AbstractLogicalExpression) e.getValue()).cloneExpression();
+            clonedArgs.add(new MutableObject<ILogicalExpression>(e2));
+        }
+        return clonedArgs;
+    }
+
+    public FunctionIdentifier getFunctionIdentifier() {
+        return finfo.getFunctionIdentifier();
+    }
+
+    public IFunctionInfo getFunctionInfo() {
+        return finfo;
+    }
+
+    public void setFunctionInfo(IFunctionInfo finfo) {
+        this.finfo = finfo;
+    }
+
+    public List<Mutable<ILogicalExpression>> getArguments() {
+        return arguments;
+    }
+
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("function-call: " + finfo.getFunctionIdentifier() + ", Args:[");
+        // + arguments;
+        boolean first = true;
+        for (Mutable<ILogicalExpression> ref : arguments) {
+            if (first) {
+                first = false;
+            } else {
+                sb.append(", ");
+            }
+            sb.append(ref.getValue());
+        }
+        sb.append("]");
+        return sb.toString();
+    }
+
+    @Override
+    public LogicalExpressionTag getExpressionTag() {
+        return LogicalExpressionTag.FUNCTION_CALL;
+    }
+
+    @Override
+    public void getUsedVariables(Collection<LogicalVariable> vars) {
+        for (Mutable<ILogicalExpression> arg : arguments) {
+            arg.getValue().getUsedVariables(vars);
+        }
+    }
+
+    @Override
+    public void substituteVar(LogicalVariable v1, LogicalVariable v2) {
+        for (Mutable<ILogicalExpression> arg : arguments) {
+            arg.getValue().substituteVar(v1, v2);
+        }
+    }
+
+    @Override
+    public void getConstraintsAndEquivClasses(Collection<FunctionalDependency> fds,
+            Map<LogicalVariable, EquivalenceClass> equivClasses) {
+        FunctionIdentifier funId = getFunctionIdentifier();
+        if (funId.equals(AlgebricksBuiltinFunctions.AND)) {
+            for (Mutable<ILogicalExpression> a : arguments) {
+                a.getValue().getConstraintsAndEquivClasses(fds, equivClasses);
+            }
+        } else if (funId.equals(AlgebricksBuiltinFunctions.EQ)) {
+            ILogicalExpression opLeft = arguments.get(0).getValue();
+            ILogicalExpression opRight = arguments.get(1).getValue();
+            if (opLeft.getExpressionTag() == LogicalExpressionTag.CONSTANT
+                    && opRight.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                ConstantExpression op1 = (ConstantExpression) opLeft;
+                VariableReferenceExpression op2 = (VariableReferenceExpression) opRight;
+                getFDsAndEquivClassesForEqWithConstant(op1, op2, fds, equivClasses);
+            } else if (opLeft.getExpressionTag() == LogicalExpressionTag.VARIABLE
+                    && opRight.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression op1 = (VariableReferenceExpression) opLeft;
+                VariableReferenceExpression op2 = (VariableReferenceExpression) opRight;
+                getFDsAndEquivClassesForColumnEq(op1, op2, fds, equivClasses);
+            }
+        }
+    }
+
+    @Override
+    public void getConstraintsForOuterJoin(Collection<FunctionalDependency> fds, Collection<LogicalVariable> outerVars) {
+        FunctionIdentifier funId = getFunctionIdentifier();
+        if (funId.equals(AlgebricksBuiltinFunctions.AND)) {
+            for (Mutable<ILogicalExpression> a : arguments) {
+                a.getValue().getConstraintsForOuterJoin(fds, outerVars);
+            }
+        } else if (funId.equals(AlgebricksBuiltinFunctions.EQ)) {
+            ILogicalExpression opLeft = arguments.get(0).getValue();
+            ILogicalExpression opRight = arguments.get(1).getValue();
+            if (opLeft.getExpressionTag() == LogicalExpressionTag.VARIABLE
+                    && opRight.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                LogicalVariable var1 = ((VariableReferenceExpression) opLeft).getVariableReference();
+                LogicalVariable var2 = ((VariableReferenceExpression) opRight).getVariableReference();
+                if (outerVars.contains(var1)) {
+                    addFD(fds, var1, var2);
+                }
+                if (outerVars.contains(var2)) {
+                    addFD(fds, var2, var1);
+                }
+            }
+        }
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof AbstractFunctionCallExpression)) {
+            return false;
+        } else {
+            AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) obj;
+            boolean equal = getFunctionIdentifier().equals(fce.getFunctionIdentifier());
+            if (!equal)
+                return false;
+            for (int i = 0; i < arguments.size(); i++) {
+                ILogicalExpression argument = arguments.get(i).getValue();
+                ILogicalExpression fceArgument = fce.getArguments().get(i).getValue();
+                if (!argument.equals(fceArgument))
+                    return false;
+            }
+            return true;
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        int h = finfo.hashCode();
+        for (Mutable<ILogicalExpression> e : arguments) {
+            h = h * 41 + e.getValue().hashCode();
+        }
+        return h;
+    }
+
+    @Override
+    public boolean splitIntoConjuncts(List<Mutable<ILogicalExpression>> conjs) {
+        if (!getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.AND) || arguments.size() <= 1) {
+            return false;
+        } else {
+            conjs.addAll(arguments);
+            return true;
+        }
+    }
+
+    public Map<Object, IExpressionAnnotation> getAnnotations() {
+        return annotationMap;
+    }
+
+    protected Map<Object, IExpressionAnnotation> cloneAnnotations() {
+        Map<Object, IExpressionAnnotation> m = new HashMap<Object, IExpressionAnnotation>();
+        for (Object k : annotationMap.keySet()) {
+            IExpressionAnnotation annot2 = annotationMap.get(k).copy();
+            m.put(k, annot2);
+        }
+        return m;
+    }
+
+    private final static void addFD(Collection<FunctionalDependency> fds, LogicalVariable var1, LogicalVariable var2) {
+        LinkedList<LogicalVariable> set1 = new LinkedList<LogicalVariable>();
+        set1.add(var1);
+        LinkedList<LogicalVariable> set2 = new LinkedList<LogicalVariable>();
+        set2.add(var2);
+        FunctionalDependency fd1 = new FunctionalDependency(set1, set2);
+        fds.add(fd1);
+    }
+
+    private final static void getFDsAndEquivClassesForEqWithConstant(ConstantExpression c,
+            VariableReferenceExpression v, Collection<FunctionalDependency> fds,
+            Map<LogicalVariable, EquivalenceClass> equivClasses) {
+        LogicalVariable var = v.getVariableReference();
+        LinkedList<LogicalVariable> head = new LinkedList<LogicalVariable>();
+        // empty set in the head
+        LinkedList<LogicalVariable> tail = new LinkedList<LogicalVariable>();
+        tail.add(var);
+        FunctionalDependency fd = new FunctionalDependency(head, tail);
+        fds.add(fd);
+
+        EquivalenceClass ec = equivClasses.get(var);
+        if (ec == null) {
+            LinkedList<LogicalVariable> members = new LinkedList<LogicalVariable>();
+            members.add(var);
+            EquivalenceClass eclass = new EquivalenceClass(members, c);
+            equivClasses.put(var, eclass);
+        } else {
+            if (ec.representativeIsConst()) {
+                ILogicalExpression c1 = ec.getConstRepresentative();
+                if (!c1.equals(c)) {
+                    // here I could also rewrite to FALSE
+                    return;
+                }
+            }
+            ec.setConstRepresentative(c);
+        }
+    }
+
+    /*
+     * Obs.: mgmt. of equiv. classes should use a more efficient data
+     * structure,if we are to implem. cost-bazed optim.
+     */
+    private final static void getFDsAndEquivClassesForColumnEq(VariableReferenceExpression v1,
+            VariableReferenceExpression v2, Collection<FunctionalDependency> fds,
+            Map<LogicalVariable, EquivalenceClass> equivClasses) {
+        LogicalVariable var1 = v1.getVariableReference();
+        LogicalVariable var2 = v2.getVariableReference();
+        LinkedList<LogicalVariable> set1 = new LinkedList<LogicalVariable>();
+        set1.add(var1);
+        LinkedList<LogicalVariable> set2 = new LinkedList<LogicalVariable>();
+        set2.add(var2);
+        FunctionalDependency fd1 = new FunctionalDependency(set1, set2);
+        FunctionalDependency fd2 = new FunctionalDependency(set2, set1);
+        fds.add(fd1);
+        fds.add(fd2);
+
+        EquivalenceClass ec1 = equivClasses.get(var1);
+        EquivalenceClass ec2 = equivClasses.get(var2);
+        if (ec1 == null && ec2 == null) {
+            LinkedList<LogicalVariable> members = new LinkedList<LogicalVariable>();
+            members.add(var1);
+            members.add(var2);
+            EquivalenceClass ec = new EquivalenceClass(members, var1);
+            equivClasses.put(var1, ec);
+            equivClasses.put(var2, ec);
+        } else if (ec1 == null && ec2 != null) {
+            ec2.addMember(var1);
+            equivClasses.put(var1, ec2);
+        } else if (ec2 == null && ec1 != null) {
+            ec1.addMember(var2);
+            equivClasses.put(var2, ec1);
+        } else {
+            ec1.merge(ec2);
+            for (LogicalVariable w : equivClasses.keySet()) {
+                if (ec2.getMembers().contains(w)) {
+                    equivClasses.put(w, ec1);
+                }
+            }
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractLogicalExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractLogicalExpression.java
new file mode 100644
index 0000000..f9b30cc
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AbstractLogicalExpression.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.Collection;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+
+public abstract class AbstractLogicalExpression implements ILogicalExpression {
+
+    @Override
+    public void getConstraintsAndEquivClasses(Collection<FunctionalDependency> fds,
+            Map<LogicalVariable, EquivalenceClass> equivClasses) {
+        // do nothing
+    }
+
+    @Override
+    public void getConstraintsForOuterJoin(Collection<FunctionalDependency> fds,
+            Collection<LogicalVariable> innerSideVars) {
+        // do nothing
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AggregateFunctionCallExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AggregateFunctionCallExpression.java
new file mode 100644
index 0000000..a720039
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/AggregateFunctionCallExpression.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+/**
+ * 
+ * An aggregate function may be executed in a "two step" mode. First the
+ * "step-one" aggregates are run and then the results are passed to the
+ * "step-two" aggregators. The convention is the following:
+ * 
+ * 1. The step-one aggregate must be able to accept the same arguments as the
+ * original aggregate function call.
+ * 
+ * 2. The step-two aggregate must be a unary function that accepts as input the
+ * output of the step-one aggregate.
+ * 
+ */
+
+public class AggregateFunctionCallExpression extends AbstractFunctionCallExpression {
+
+    private boolean twoStep;
+    private IFunctionInfo stepOneAggregate;
+    private IFunctionInfo stepTwoAggregate;
+
+    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep) {
+        super(FunctionKind.AGGREGATE, finfo);
+        this.twoStep = isTwoStep;
+    }
+
+    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep,
+            List<Mutable<ILogicalExpression>> arguments) {
+        super(FunctionKind.AGGREGATE, finfo, arguments);
+        this.twoStep = isTwoStep;
+    }
+
+    public AggregateFunctionCallExpression(IFunctionInfo finfo, boolean isTwoStep,
+            Mutable<ILogicalExpression>... expressions) {
+        super(FunctionKind.AGGREGATE, finfo, expressions);
+        this.twoStep = isTwoStep;
+    }
+
+    public boolean isTwoStep() {
+        return twoStep;
+    }
+
+    public void setTwoStep(boolean twoStep) {
+        this.twoStep = twoStep;
+    }
+
+    @Override
+    public AggregateFunctionCallExpression cloneExpression() {
+        cloneAnnotations();
+        List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
+        AggregateFunctionCallExpression fun = new AggregateFunctionCallExpression(finfo, twoStep, clonedArgs);
+        fun.setStepTwoAggregate(stepTwoAggregate);
+        fun.setStepOneAggregate(stepOneAggregate);
+        return fun;
+    }
+
+    public void setStepOneAggregate(IFunctionInfo stepOneAggregate) {
+        this.stepOneAggregate = stepOneAggregate;
+    }
+
+    public IFunctionInfo getStepOneAggregate() {
+        return stepOneAggregate;
+    }
+
+    public void setStepTwoAggregate(IFunctionInfo stepTwoAggregate) {
+        this.stepTwoAggregate = stepTwoAggregate;
+    }
+
+    public IFunctionInfo getStepTwoAggregate() {
+        return stepTwoAggregate;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitAggregateFunctionCallExpression(this, arg);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/BroadcastExpressionAnnotation.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/BroadcastExpressionAnnotation.java
new file mode 100644
index 0000000..ff88912
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/BroadcastExpressionAnnotation.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+public class BroadcastExpressionAnnotation implements IExpressionAnnotation {
+
+    public static final String BROADCAST_ANNOTATION_KEY = "broadcast";
+
+    public enum BroadcastSide {
+        LEFT,
+        RIGHT
+    };
+
+    private BroadcastSide side;
+
+    @Override
+    public Object getObject() {
+        return side;
+    }
+
+    @Override
+    public void setObject(Object side) {
+        this.side = (BroadcastSide) side;
+    }
+
+    @Override
+    public IExpressionAnnotation copy() {
+        BroadcastExpressionAnnotation bcast = new BroadcastExpressionAnnotation();
+        bcast.side = side;
+        return bcast;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ConstantExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ConstantExpression.java
new file mode 100644
index 0000000..a0b7674
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ConstantExpression.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public final class ConstantExpression extends AbstractLogicalExpression {
+    private IAlgebricksConstantValue value;
+
+    public final static ConstantExpression TRUE = new ConstantExpression(new IAlgebricksConstantValue() {
+
+        @Override
+        public boolean isTrue() {
+            return true;
+        }
+
+        @Override
+        public boolean isNull() {
+            return false;
+        }
+
+        @Override
+        public boolean isFalse() {
+            return false;
+        }
+
+        @Override
+        public String toString() {
+            return "TRUE";
+        }
+    });
+    public final static ConstantExpression FALSE = new ConstantExpression(new IAlgebricksConstantValue() {
+
+        @Override
+        public boolean isTrue() {
+            return false;
+        }
+
+        @Override
+        public boolean isNull() {
+            return false;
+        }
+
+        @Override
+        public boolean isFalse() {
+            return true;
+        }
+
+        @Override
+        public String toString() {
+            return "FALSE";
+        }
+    });
+    public final static ConstantExpression NULL = new ConstantExpression(new IAlgebricksConstantValue() {
+
+        @Override
+        public boolean isTrue() {
+            return false;
+        }
+
+        @Override
+        public boolean isNull() {
+            return true;
+        }
+
+        @Override
+        public boolean isFalse() {
+            return false;
+        }
+
+        @Override
+        public String toString() {
+            return "NULL";
+        }
+    });
+
+    private Map<Object, IExpressionAnnotation> annotationMap = new HashMap<Object, IExpressionAnnotation>();
+
+    public ConstantExpression(IAlgebricksConstantValue value) {
+        this.value = value;
+    }
+
+    public IAlgebricksConstantValue getValue() {
+        return value;
+    }
+
+    public void setValue(IAlgebricksConstantValue value) {
+        this.value = value;
+    }
+
+    @Override
+    public LogicalExpressionTag getExpressionTag() {
+        return LogicalExpressionTag.CONSTANT;
+    }
+
+    @Override
+    public String toString() {
+        return value.toString();
+    }
+
+    @Override
+    public void getUsedVariables(Collection<LogicalVariable> vars) {
+        // do nothing
+    }
+
+    @Override
+    public void substituteVar(LogicalVariable v1, LogicalVariable v2) {
+        // do nothing
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof ConstantExpression)) {
+            return false;
+        } else {
+            return value.equals(((ConstantExpression) obj).getValue());
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        return value.hashCode();
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitConstantExpression(this, arg);
+    }
+
+    @Override
+    public AbstractLogicalExpression cloneExpression() {
+        Map<Object, IExpressionAnnotation> m = new HashMap<Object, IExpressionAnnotation>();
+        for (Object k : annotationMap.keySet()) {
+            IExpressionAnnotation annot2 = annotationMap.get(k).copy();
+            m.put(k, annot2);
+        }
+        ConstantExpression c = new ConstantExpression(value);
+        c.annotationMap = m;
+        return c;
+    }
+
+    public Map<Object, IExpressionAnnotation> getAnnotations() {
+        return annotationMap;
+    }
+
+    @Override
+    public boolean splitIntoConjuncts(List<Mutable<ILogicalExpression>> conjs) {
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ExpressionAnnotationNoCopyImpl.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ExpressionAnnotationNoCopyImpl.java
new file mode 100644
index 0000000..6870a38
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ExpressionAnnotationNoCopyImpl.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+public class ExpressionAnnotationNoCopyImpl implements IExpressionAnnotation {
+
+    private Object object;
+
+    @Override
+    public IExpressionAnnotation copy() {
+        return this;
+    }
+
+    @Override
+    public Object getObject() {
+        return object;
+    }
+
+    @Override
+    public void setObject(Object object) {
+        this.object = object;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IAlgebricksConstantValue.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IAlgebricksConstantValue.java
new file mode 100644
index 0000000..b6c7dbd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IAlgebricksConstantValue.java
@@ -0,0 +1,9 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+public interface IAlgebricksConstantValue {
+    public boolean isNull();
+
+    public boolean isTrue();
+
+    public boolean isFalse();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionAnnotation.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionAnnotation.java
new file mode 100644
index 0000000..15e543b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionAnnotation.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+public interface IExpressionAnnotation {
+    public Object getObject();
+
+    public void setObject(Object object);
+
+    public IExpressionAnnotation copy();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionEvalSizeComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionEvalSizeComputer.java
new file mode 100644
index 0000000..623f7bb
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionEvalSizeComputer.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+
+public interface IExpressionEvalSizeComputer {
+    // size in bytes, or -1 if unknown
+    public int getEvalSize(ILogicalExpression expr, IVariableEvalSizeEnvironment env) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionRuntimeProvider.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionRuntimeProvider.java
new file mode 100644
index 0000000..5db1a0d
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionRuntimeProvider.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopySerializableAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IRunningAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IUnnestingEvaluatorFactory;
+
+public interface IExpressionRuntimeProvider {
+    public IScalarEvaluatorFactory createEvaluatorFactory(ILogicalExpression expr, IVariableTypeEnvironment env,
+            IOperatorSchema[] inputSchemas, JobGenContext context) throws AlgebricksException;
+
+    public IAggregateEvaluatorFactory createAggregateFunctionFactory(AggregateFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+
+    public ICopySerializableAggregateFunctionFactory createSerializableAggregateFunctionFactory(
+            AggregateFunctionCallExpression expr, IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas,
+            JobGenContext context) throws AlgebricksException;
+
+    public IRunningAggregateEvaluatorFactory createRunningAggregateFunctionFactory(StatefulFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+
+    public IUnnestingEvaluatorFactory createUnnestingFunctionFactory(UnnestingFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionTypeComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionTypeComputer.java
new file mode 100644
index 0000000..3057d8a
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IExpressionTypeComputer.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public interface IExpressionTypeComputer {
+    public Object getType(ILogicalExpression expr, IMetadataProvider<?, ?> metadataProvider,
+            IVariableTypeEnvironment env) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ILogicalExpressionJobGen.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ILogicalExpressionJobGen.java
new file mode 100644
index 0000000..8d46662
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ILogicalExpressionJobGen.java
@@ -0,0 +1,48 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyRunningAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopySerializableAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyUnnestingFunctionFactory;
+
+public interface ILogicalExpressionJobGen {
+
+    public ICopyEvaluatorFactory createEvaluatorFactory(ILogicalExpression expr, IVariableTypeEnvironment env,
+            IOperatorSchema[] inputSchemas, JobGenContext context) throws AlgebricksException;
+
+    public ICopyAggregateFunctionFactory createAggregateFunctionFactory(AggregateFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+
+    public ICopySerializableAggregateFunctionFactory createSerializableAggregateFunctionFactory(
+            AggregateFunctionCallExpression expr, IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas,
+            JobGenContext context) throws AlgebricksException;
+
+    public ICopyRunningAggregateFunctionFactory createRunningAggregateFunctionFactory(StatefulFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+
+    public ICopyUnnestingFunctionFactory createUnnestingFunctionFactory(UnnestingFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException;
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IMergeAggregationExpressionFactory.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IMergeAggregationExpressionFactory.java
new file mode 100644
index 0000000..04bb824
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IMergeAggregationExpressionFactory.java
@@ -0,0 +1,10 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+
+public interface IMergeAggregationExpressionFactory {
+    ILogicalExpression createMergeAggregation(ILogicalExpression expr, IOptimizationContext env)
+            throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/INullableTypeComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/INullableTypeComputer.java
new file mode 100644
index 0000000..37b6d80
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/INullableTypeComputer.java
@@ -0,0 +1,7 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+
+public interface INullableTypeComputer {
+    public Object makeNullableType(Object type) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IPartialAggregationTypeComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IPartialAggregationTypeComputer.java
new file mode 100644
index 0000000..5921335
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IPartialAggregationTypeComputer.java
@@ -0,0 +1,10 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public interface IPartialAggregationTypeComputer {
+    public Object getType(ILogicalExpression expr, IVariableTypeEnvironment env,
+            IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableEvalSizeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableEvalSizeEnvironment.java
new file mode 100644
index 0000000..f6799b0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableEvalSizeEnvironment.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IVariableEvalSizeEnvironment {
+    // size in bytes or -1 if unknown
+    public int getVariableEvalSize(LogicalVariable var);
+
+    public void setVariableEvalSize(LogicalVariable var, int size);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableTypeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableTypeEnvironment.java
new file mode 100644
index 0000000..2275227
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IVariableTypeEnvironment.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IVariableTypeEnvironment {
+    public Object getVarType(LogicalVariable var) throws AlgebricksException;
+
+    public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariables) throws AlgebricksException;
+
+    public void setVarType(LogicalVariable var, Object type);
+
+    public Object getType(ILogicalExpression expr) throws AlgebricksException;
+
+    public boolean substituteProducedVariable(LogicalVariable v1, LogicalVariable v2) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IndexedNLJoinExpressionAnnotation.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IndexedNLJoinExpressionAnnotation.java
new file mode 100644
index 0000000..709bfa1
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/IndexedNLJoinExpressionAnnotation.java
@@ -0,0 +1,26 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+public class IndexedNLJoinExpressionAnnotation implements IExpressionAnnotation {
+
+    public static final String INDEXED_NL_JOIN_ANNOTATION_KEY = "indexnl";
+    public static final IndexedNLJoinExpressionAnnotation INSTANCE = new IndexedNLJoinExpressionAnnotation();
+
+    private Object object;
+
+    @Override
+    public Object getObject() {
+        return object;
+    }
+
+    @Override
+    public void setObject(Object object) {
+        this.object = object;
+    }
+
+    @Override
+    public IExpressionAnnotation copy() {
+        IndexedNLJoinExpressionAnnotation clone = new IndexedNLJoinExpressionAnnotation();
+        clone.setObject(object);
+        return clone;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/LogicalExpressionJobGenToExpressionRuntimeProviderAdapter.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/LogicalExpressionJobGenToExpressionRuntimeProviderAdapter.java
new file mode 100644
index 0000000..91c9eae
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/LogicalExpressionJobGenToExpressionRuntimeProviderAdapter.java
@@ -0,0 +1,193 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IAggregateEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyAggregateFunction;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyRunningAggregateFunction;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyRunningAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopySerializableAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyUnnestingFunction;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopyUnnestingFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IRunningAggregateEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IRunningAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IUnnestingEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IUnnestingEvaluatorFactory;
+import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
+import edu.uci.ics.hyracks.data.std.api.IPointable;
+import edu.uci.ics.hyracks.data.std.util.ArrayBackedValueStorage;
+import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
+
+public class LogicalExpressionJobGenToExpressionRuntimeProviderAdapter implements IExpressionRuntimeProvider {
+    private final ILogicalExpressionJobGen lejg;
+
+    public LogicalExpressionJobGenToExpressionRuntimeProviderAdapter(ILogicalExpressionJobGen lejg) {
+        this.lejg = lejg;
+    }
+
+    @Override
+    public IScalarEvaluatorFactory createEvaluatorFactory(ILogicalExpression expr, IVariableTypeEnvironment env,
+            IOperatorSchema[] inputSchemas, JobGenContext context) throws AlgebricksException {
+        ICopyEvaluatorFactory cef = lejg.createEvaluatorFactory(expr, env, inputSchemas, context);
+        return new ScalarEvaluatorFactoryAdapter(cef);
+    }
+
+    @Override
+    public IAggregateEvaluatorFactory createAggregateFunctionFactory(AggregateFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException {
+        ICopyAggregateFunctionFactory caff = lejg.createAggregateFunctionFactory(expr, env, inputSchemas, context);
+        return new AggregateFunctionFactoryAdapter(caff);
+    }
+
+    @Override
+    public ICopySerializableAggregateFunctionFactory createSerializableAggregateFunctionFactory(
+            AggregateFunctionCallExpression expr, IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas,
+            JobGenContext context) throws AlgebricksException {
+        return lejg.createSerializableAggregateFunctionFactory(expr, env, inputSchemas, context);
+    }
+
+    @Override
+    public IRunningAggregateEvaluatorFactory createRunningAggregateFunctionFactory(StatefulFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException {
+        ICopyRunningAggregateFunctionFactory craff = lejg.createRunningAggregateFunctionFactory(expr, env,
+                inputSchemas, context);
+        return new RunningAggregateFunctionFactoryAdapter(craff);
+    }
+
+    @Override
+    public IUnnestingEvaluatorFactory createUnnestingFunctionFactory(UnnestingFunctionCallExpression expr,
+            IVariableTypeEnvironment env, IOperatorSchema[] inputSchemas, JobGenContext context)
+            throws AlgebricksException {
+        ICopyUnnestingFunctionFactory cuff = lejg.createUnnestingFunctionFactory(expr, env, inputSchemas, context);
+        return new UnnestingFunctionFactoryAdapter(cuff);
+    }
+
+    public static final class ScalarEvaluatorFactoryAdapter implements IScalarEvaluatorFactory {
+        private static final long serialVersionUID = 1L;
+
+        private final ICopyEvaluatorFactory cef;
+
+        public ScalarEvaluatorFactoryAdapter(ICopyEvaluatorFactory cef) {
+            this.cef = cef;
+        }
+
+        @Override
+        public IScalarEvaluator createScalarEvaluator(IHyracksTaskContext ctx) throws AlgebricksException {
+            final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
+            final ICopyEvaluator ce = cef.createEvaluator(abvs);
+            return new IScalarEvaluator() {
+                @Override
+                public void evaluate(IFrameTupleReference tuple, IPointable result) throws AlgebricksException {
+                    abvs.reset();
+                    ce.evaluate(tuple);
+                    result.set(abvs);
+                }
+            };
+        }
+    }
+
+    public static final class AggregateFunctionFactoryAdapter implements IAggregateEvaluatorFactory {
+        private static final long serialVersionUID = 1L;
+
+        private final ICopyAggregateFunctionFactory caff;
+
+        public AggregateFunctionFactoryAdapter(ICopyAggregateFunctionFactory caff) {
+            this.caff = caff;
+        }
+
+        @Override
+        public IAggregateEvaluator createAggregateEvaluator(IHyracksTaskContext ctx) throws AlgebricksException {
+            final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
+            final ICopyAggregateFunction caf = caff.createAggregateFunction(abvs);
+            return new IAggregateEvaluator() {
+                @Override
+                public void step(IFrameTupleReference tuple) throws AlgebricksException {
+                    caf.step(tuple);
+                }
+
+                @Override
+                public void init() throws AlgebricksException {
+                    abvs.reset();
+                    caf.init();
+                }
+
+                @Override
+                public void finish(IPointable result) throws AlgebricksException {
+                    caf.finish();
+                    result.set(abvs);
+                }
+            };
+        }
+    }
+
+    public static final class RunningAggregateFunctionFactoryAdapter implements IRunningAggregateEvaluatorFactory {
+        private static final long serialVersionUID = 1L;
+
+        private final ICopyRunningAggregateFunctionFactory craff;
+
+        public RunningAggregateFunctionFactoryAdapter(ICopyRunningAggregateFunctionFactory craff) {
+            this.craff = craff;
+        }
+
+        @Override
+        public IRunningAggregateEvaluator createRunningAggregateEvaluator() throws AlgebricksException {
+            final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
+            final ICopyRunningAggregateFunction craf = craff.createRunningAggregateFunction(abvs);
+            return new IRunningAggregateEvaluator() {
+                @Override
+                public void step(IFrameTupleReference tuple, IPointable result) throws AlgebricksException {
+                    abvs.reset();
+                    craf.step(tuple);
+                    result.set(abvs);
+                }
+
+                @Override
+                public void init() throws AlgebricksException {
+                    craf.init();
+                }
+            };
+        }
+    }
+
+    public static final class UnnestingFunctionFactoryAdapter implements IUnnestingEvaluatorFactory {
+        private static final long serialVersionUID = 1L;
+
+        private final ICopyUnnestingFunctionFactory cuff;
+
+        public UnnestingFunctionFactoryAdapter(ICopyUnnestingFunctionFactory cuff) {
+            this.cuff = cuff;
+        }
+
+        @Override
+        public IUnnestingEvaluator createUnnestingEvaluator(IHyracksTaskContext ctx) throws AlgebricksException {
+            final ArrayBackedValueStorage abvs = new ArrayBackedValueStorage();
+            final ICopyUnnestingFunction cuf = cuff.createUnnestingFunction(abvs);
+            return new IUnnestingEvaluator() {
+                @Override
+                public boolean step(IPointable result) throws AlgebricksException {
+                    abvs.reset();
+                    if (cuf.step()) {
+                        result.set(abvs);
+                        return true;
+                    }
+                    return false;
+                }
+
+                @Override
+                public void init(IFrameTupleReference tuple) throws AlgebricksException {
+                    cuf.init(tuple);
+                }
+            };
+        }
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java
new file mode 100644
index 0000000..bf3f82b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public class ScalarFunctionCallExpression extends AbstractFunctionCallExpression {
+
+    public ScalarFunctionCallExpression(IFunctionInfo finfo) {
+        super(FunctionKind.SCALAR, finfo);
+    }
+
+    public ScalarFunctionCallExpression(IFunctionInfo finfo, List<Mutable<ILogicalExpression>> arguments) {
+        super(FunctionKind.SCALAR, finfo, arguments);
+    }
+
+    public ScalarFunctionCallExpression(IFunctionInfo finfo, Mutable<ILogicalExpression>... expressions) {
+        super(FunctionKind.SCALAR, finfo, expressions);
+    }
+
+    @Override
+    public ScalarFunctionCallExpression cloneExpression() {
+        cloneAnnotations();
+        List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
+        return new ScalarFunctionCallExpression(finfo, clonedArgs);
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitScalarFunctionCallExpression(this, arg);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/StatefulFunctionCallExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/StatefulFunctionCallExpression.java
new file mode 100644
index 0000000..40f25b2
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/StatefulFunctionCallExpression.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPropertiesComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public class StatefulFunctionCallExpression extends AbstractFunctionCallExpression {
+
+    private final IPropertiesComputer propertiesComputer;
+
+    public StatefulFunctionCallExpression(IFunctionInfo finfo, IPropertiesComputer propertiesComputer) {
+        super(FunctionKind.STATEFUL, finfo);
+        this.propertiesComputer = propertiesComputer;
+    }
+
+    public StatefulFunctionCallExpression(IFunctionInfo finfo, IPropertiesComputer propertiesComputer,
+            List<Mutable<ILogicalExpression>> arguments) {
+        super(FunctionKind.STATEFUL, finfo, arguments);
+        this.propertiesComputer = propertiesComputer;
+    }
+
+    public StatefulFunctionCallExpression(IFunctionInfo finfo, IPropertiesComputer propertiesComputer,
+            Mutable<ILogicalExpression>... expressions) {
+        super(FunctionKind.STATEFUL, finfo, expressions);
+        this.propertiesComputer = propertiesComputer;
+    }
+
+    @Override
+    public StatefulFunctionCallExpression cloneExpression() {
+        cloneAnnotations();
+        List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
+        return new StatefulFunctionCallExpression(finfo, propertiesComputer, clonedArgs);
+    }
+
+    // can be null
+    public IPartitioningProperty getRequiredPartitioningProperty() {
+        return propertiesComputer.computePartitioningProperty(this);
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitStatefulFunctionCallExpression(this, arg);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java
new file mode 100644
index 0000000..71932d8
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public class UnnestingFunctionCallExpression extends AbstractFunctionCallExpression {
+
+    private boolean returnsUniqueValues;
+
+    public UnnestingFunctionCallExpression(IFunctionInfo finfo) {
+        super(FunctionKind.UNNEST, finfo);
+    }
+
+    public UnnestingFunctionCallExpression(IFunctionInfo finfo, List<Mutable<ILogicalExpression>> arguments) {
+        super(FunctionKind.UNNEST, finfo, arguments);
+    }
+
+    public UnnestingFunctionCallExpression(IFunctionInfo finfo, Mutable<ILogicalExpression>... expressions) {
+        super(FunctionKind.UNNEST, finfo, expressions);
+    }
+
+    @Override
+    public UnnestingFunctionCallExpression cloneExpression() {
+        cloneAnnotations();
+        List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
+        UnnestingFunctionCallExpression ufce = new UnnestingFunctionCallExpression(finfo, clonedArgs);
+        ufce.setReturnsUniqueValues(returnsUniqueValues);
+        return ufce;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitUnnestingFunctionCallExpression(this, arg);
+    }
+
+    public void setReturnsUniqueValues(boolean returnsUniqueValues) {
+        this.returnsUniqueValues = returnsUniqueValues;
+    }
+
+    public boolean returnsUniqueValues() {
+        return returnsUniqueValues;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/VariableReferenceExpression.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/VariableReferenceExpression.java
new file mode 100644
index 0000000..76a7ec6
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/VariableReferenceExpression.java
@@ -0,0 +1,110 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.expressions;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionVisitor;
+
+public class VariableReferenceExpression extends AbstractLogicalExpression {
+    private int tupleRef;
+    private LogicalVariable variable;
+
+    public VariableReferenceExpression(int tupleRef, LogicalVariable variable) {
+        this.tupleRef = tupleRef;
+        this.variable = variable;
+    }
+
+    public VariableReferenceExpression(LogicalVariable variable) {
+        this(0, variable);
+    }
+
+    public int getTupleRef() {
+        return tupleRef;
+    }
+
+    public void setTupleRef(int tupleRef) {
+        this.tupleRef = tupleRef;
+    }
+
+    public LogicalVariable getVariableReference() {
+        return variable;
+    }
+
+    public void setVariable(LogicalVariable variable) {
+        this.variable = variable;
+    }
+
+    @Override
+    public LogicalExpressionTag getExpressionTag() {
+        return LogicalExpressionTag.VARIABLE;
+    }
+
+    @Override
+    public String toString() {
+        return "%" + tupleRef + "->" + variable.toString();
+    }
+
+    @Override
+    public void getUsedVariables(Collection<LogicalVariable> vars) {
+        // if (!vars.contains(variable)) {
+        vars.add(variable);
+        // }
+    }
+
+    @Override
+    public void substituteVar(LogicalVariable v1, LogicalVariable v2) {
+        if (variable.equals(v1)) {
+            variable = v2;
+        }
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof VariableReferenceExpression)) {
+            return false;
+        } else {
+            return tupleRef == ((VariableReferenceExpression) obj).tupleRef
+                    && variable.equals(((VariableReferenceExpression) obj).getVariableReference());
+        }
+    }
+
+    @Override
+    public int hashCode() {
+        return tupleRef + variable.getId();
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalExpressionVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitVariableReferenceExpression(this, arg);
+    }
+
+    @Override
+    public AbstractLogicalExpression cloneExpression() {
+        return new VariableReferenceExpression(variable);
+    }
+
+    @Override
+    public boolean splitIntoConjuncts(List<Mutable<ILogicalExpression>> conjs) {
+        return false;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/AlgebricksBuiltinFunctions.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/AlgebricksBuiltinFunctions.java
new file mode 100644
index 0000000..de9cf29
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/AlgebricksBuiltinFunctions.java
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.functions;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class AlgebricksBuiltinFunctions {
+    public enum ComparisonKind {
+        EQ,
+        LE,
+        GE,
+        LT,
+        GT,
+        NEQ
+    }
+
+    public static final String ALGEBRICKS_NS = "algebricks";
+
+    // comparisons
+    public final static FunctionIdentifier EQ = new FunctionIdentifier(ALGEBRICKS_NS, "eq", 2);
+    public final static FunctionIdentifier LE = new FunctionIdentifier(ALGEBRICKS_NS, "le", 2);
+    public final static FunctionIdentifier GE = new FunctionIdentifier(ALGEBRICKS_NS, "ge", 2);
+    public final static FunctionIdentifier LT = new FunctionIdentifier(ALGEBRICKS_NS, "lt", 2);
+    public final static FunctionIdentifier GT = new FunctionIdentifier(ALGEBRICKS_NS, "gt", 2);
+    public final static FunctionIdentifier NEQ = new FunctionIdentifier(ALGEBRICKS_NS, "neq", 2);
+
+    // booleans
+    public final static FunctionIdentifier NOT = new FunctionIdentifier(ALGEBRICKS_NS, "not", 1);
+    public final static FunctionIdentifier AND = new FunctionIdentifier(ALGEBRICKS_NS, "and",
+            FunctionIdentifier.VARARGS);
+    public final static FunctionIdentifier OR = new FunctionIdentifier(ALGEBRICKS_NS, "or", FunctionIdentifier.VARARGS);
+
+    // numerics
+    public final static FunctionIdentifier NUMERIC_ADD = new FunctionIdentifier(ALGEBRICKS_NS, "numeric-add", 2);
+
+    // nulls
+    public final static FunctionIdentifier IS_NULL = new FunctionIdentifier(ALGEBRICKS_NS, "is-null", 1);
+
+    private static final Map<FunctionIdentifier, ComparisonKind> comparisonFunctions = new HashMap<FunctionIdentifier, ComparisonKind>();
+    static {
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.EQ, ComparisonKind.EQ);
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.LE, ComparisonKind.LE);
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.GE, ComparisonKind.GE);
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.LT, ComparisonKind.LT);
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.GT, ComparisonKind.GT);
+        comparisonFunctions.put(AlgebricksBuiltinFunctions.NEQ, ComparisonKind.NEQ);
+    }
+
+    public static ComparisonKind getComparisonType(FunctionIdentifier fi) {
+        return comparisonFunctions.get(fi);
+    }
+
+    public static boolean isComparisonFunction(FunctionIdentifier fi) {
+        return comparisonFunctions.get(fi) != null;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/FunctionIdentifier.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/FunctionIdentifier.java
new file mode 100644
index 0000000..548f646
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/FunctionIdentifier.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.functions;
+
+import java.io.Serializable;
+
+public final class FunctionIdentifier implements Serializable {
+    private static final long serialVersionUID = 1L;
+
+    private final String namespace;
+    private final String name;
+    private final int arity;
+
+    public final static int VARARGS = -1;
+
+    public FunctionIdentifier(String namespace, String name) {
+        this(namespace, name, VARARGS);
+    }
+
+    public FunctionIdentifier(String namespace, String name, int arity) {
+        this.namespace = namespace;
+        this.name = name;
+        this.arity = arity;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (super.equals(o)) {
+            return true;
+        }
+        if (o instanceof FunctionIdentifier) {
+            FunctionIdentifier ofi = (FunctionIdentifier) o;
+            return ofi.getNamespace().equals(getNamespace()) && ofi.name.equals(name);
+        }
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return name.hashCode() + namespace.hashCode();
+    }
+
+    public String toString() {
+        return getNamespace() + ":" + name;
+    }
+
+    public int getArity() {
+        return arity;
+    }
+
+    public String getNamespace() {
+        return namespace;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/IFunctionInfo.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/IFunctionInfo.java
new file mode 100644
index 0000000..96afc8e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/functions/IFunctionInfo.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.functions;
+
+
+public interface IFunctionInfo {
+    FunctionIdentifier getFunctionIdentifier();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSink.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSink.java
new file mode 100644
index 0000000..00b3554
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSink.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.metadata;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+
+public interface IDataSink {
+    public Object getId();
+
+    public Object[] getSchemaTypes();
+
+    public IPartitioningProperty getPartitioningProperty();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSource.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSource.java
new file mode 100644
index 0000000..22f9feb
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSource.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.metadata;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+
+public interface IDataSource<T> {
+    public T getId();
+
+    public Object[] getSchemaTypes();
+
+    public IDataSourcePropertiesProvider getPropertiesProvider();
+
+    public void computeFDs(List<LogicalVariable> scanVariables, List<FunctionalDependency> fdList);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourceIndex.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourceIndex.java
new file mode 100644
index 0000000..90c8536
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourceIndex.java
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.metadata;
+
+public interface IDataSourceIndex<I, T> {
+    public I getId();
+
+    public IDataSource<T> getDataSource();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourcePropertiesProvider.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourcePropertiesProvider.java
new file mode 100644
index 0000000..500b968
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IDataSourcePropertiesProvider.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.metadata;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+
+public interface IDataSourcePropertiesProvider {
+    public IPhysicalPropertiesVector computePropertiesVector(List<LogicalVariable> scanVariables);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java
new file mode 100644
index 0000000..899b633
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java
@@ -0,0 +1,139 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.metadata;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.IFunctionInfo;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IPushRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public interface IMetadataProvider<S, I> {
+    public IDataSource<S> findDataSource(S id) throws AlgebricksException;
+
+    /**
+     * Obs: A scanner may choose to contribute a null
+     * AlgebricksPartitionConstraint and implement
+     * contributeSchedulingConstraints instead.
+     */
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getScannerRuntime(IDataSource<S> dataSource,
+            List<LogicalVariable> scanVariables, List<LogicalVariable> projectVariables, boolean projectPushed,
+            IOperatorSchema opSchema, IVariableTypeEnvironment typeEnv, JobGenContext context, JobSpecification jobSpec)
+            throws AlgebricksException;
+
+    public boolean scannerOperatorIsLeaf(IDataSource<S> dataSource);
+
+    public Pair<IPushRuntimeFactory, AlgebricksPartitionConstraint> getWriteFileRuntime(IDataSink sink,
+            int[] printColumns, IPrinterFactory[] printerFactories, RecordDescriptor inputDesc)
+            throws AlgebricksException;
+
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getWriteResultRuntime(IDataSource<S> dataSource,
+            IOperatorSchema propagatedSchema, List<LogicalVariable> keys, LogicalVariable payLoadVar,
+            JobGenContext context, JobSpecification jobSpec) throws AlgebricksException;
+
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getInsertRuntime(IDataSource<S> dataSource,
+            IOperatorSchema propagatedSchema, List<LogicalVariable> keys, LogicalVariable payLoadVar,
+            RecordDescriptor recordDesc, JobGenContext context, JobSpecification jobSpec) throws AlgebricksException;
+
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getDeleteRuntime(IDataSource<S> dataSource,
+            IOperatorSchema propagatedSchema, List<LogicalVariable> keys, LogicalVariable payLoadVar,
+            RecordDescriptor recordDesc, JobGenContext context, JobSpecification jobSpec) throws AlgebricksException;
+
+    /**
+     * Creates the insert runtime of IndexInsertDeletePOperator, which models
+     * insert/delete operations into a secondary index.
+     * 
+     * @param dataSource
+     *            Target secondary index.
+     * @param propagatedSchema
+     *            Output schema of the insert/delete operator to be created.
+     * @param inputSchemas
+     *            Output schemas of the insert/delete operator to be created.
+     * @param typeEnv
+     *            Type environment of the original IndexInsertDeleteOperator operator.
+     * @param primaryKeys
+     *            Variables for the dataset's primary keys that the dataSource secondary index belongs to.
+     * @param secondaryKeys
+     *            Variables for the secondary-index keys.
+     * @param filterExpr
+     *            Filtering expression to be pushed inside the runtime op.
+     *            Such a filter may, e.g., exclude NULLs from being inserted/deleted.
+     * @param recordDesc
+     *            Output record descriptor of the runtime op to be created.
+     * @param context
+     *            Job generation context.
+     * @param spec
+     *            Target job specification.
+     * @return
+     *         A Hyracks IOperatorDescriptor and its partition constraint.
+     * @throws AlgebricksException
+     */
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getIndexInsertRuntime(
+            IDataSourceIndex<I, S> dataSource, IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas,
+            IVariableTypeEnvironment typeEnv, List<LogicalVariable> primaryKeys, List<LogicalVariable> secondaryKeys,
+            ILogicalExpression filterExpr, RecordDescriptor recordDesc, JobGenContext context, JobSpecification spec)
+            throws AlgebricksException;
+
+    /**
+     * Creates the delete runtime of IndexInsertDeletePOperator, which models
+     * insert/delete operations into a secondary index.
+     * 
+     * @param dataSource
+     *            Target secondary index.
+     * @param propagatedSchema
+     *            Output schema of the insert/delete operator to be created.
+     * @param inputSchemas
+     *            Output schemas of the insert/delete operator to be created.
+     * @param typeEnv
+     *            Type environment of the original IndexInsertDeleteOperator operator.
+     * @param primaryKeys
+     *            Variables for the dataset's primary keys that the dataSource secondary index belongs to.
+     * @param secondaryKeys
+     *            Variables for the secondary-index keys.
+     * @param filterExpr
+     *            Filtering expression to be pushed inside the runtime op.
+     *            Such a filter may, e.g., exclude NULLs from being inserted/deleted.
+     * @param recordDesc
+     *            Output record descriptor of the runtime op to be created.
+     * @param context
+     *            Job generation context.
+     * @param spec
+     *            Target job specification.
+     * @return
+     *         A Hyracks IOperatorDescriptor and its partition constraint.
+     * @throws AlgebricksException
+     */
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getIndexDeleteRuntime(
+            IDataSourceIndex<I, S> dataSource, IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas,
+            IVariableTypeEnvironment typeEnv, List<LogicalVariable> primaryKeys, List<LogicalVariable> secondaryKeys,
+            ILogicalExpression filterExpr, RecordDescriptor recordDesc, JobGenContext context, JobSpecification spec)
+            throws AlgebricksException;
+
+    public IDataSourceIndex<I, S> findDataSourceIndex(I indexId, S dataSourceId) throws AlgebricksException;
+
+    public IFunctionInfo lookupFunction(FunctionIdentifier fid);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractAssignOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractAssignOperator.java
new file mode 100644
index 0000000..0e83902
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractAssignOperator.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+
+/**
+ * @author Nicola
+ */
+public abstract class AbstractAssignOperator extends AbstractLogicalOperator {
+    protected final List<LogicalVariable> variables;
+    protected final List<Mutable<ILogicalExpression>> expressions;
+
+    public AbstractAssignOperator() {
+        this.variables = new ArrayList<LogicalVariable>();
+        this.expressions = new ArrayList<Mutable<ILogicalExpression>>();
+    }
+
+    public AbstractAssignOperator(List<LogicalVariable> variables, List<Mutable<ILogicalExpression>> expressions) {
+        this.variables = variables;
+        this.expressions = expressions;
+    }
+
+    public List<LogicalVariable> getVariables() {
+        return variables;
+    }
+
+    public List<Mutable<ILogicalExpression>> getExpressions() {
+        return expressions;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+        schema.addAll(variables);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean modif = false;
+        for (int i = 0; i < expressions.size(); i++) {
+            if (visitor.transform(expressions.get(i))) {
+                modif = true;
+            }
+        }
+        return modif;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractBinaryJoinOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractBinaryJoinOperator.java
new file mode 100644
index 0000000..5ab44a4
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractBinaryJoinOperator.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+
+public abstract class AbstractBinaryJoinOperator extends AbstractLogicalOperator {
+    protected final Mutable<ILogicalExpression> condition;
+    protected JoinKind joinKind;
+
+    public enum JoinKind {
+        INNER,
+        LEFT_OUTER
+    }
+
+    public AbstractBinaryJoinOperator(JoinKind joinKind, Mutable<ILogicalExpression> condition) {
+        this.joinKind = joinKind;
+        this.condition = condition;
+    }
+
+    public AbstractBinaryJoinOperator(JoinKind joinKind, Mutable<ILogicalExpression> condition,
+            Mutable<ILogicalOperator> input1, Mutable<ILogicalOperator> input2) {
+        this(joinKind, condition);
+        inputs.add(input1);
+        inputs.add(input2);
+    }
+
+    public Mutable<ILogicalExpression> getCondition() {
+        return condition;
+    }
+
+    public JoinKind getJoinKind() {
+        return joinKind;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+        schema.addAll(inputs.get(1).getValue().getSchema());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.concat(VariablePropagationPolicy.ALL, VariablePropagationPolicy.ALL);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return visitor.transform(condition);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractExtensibleLogicalOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractExtensibleLogicalOperator.java
new file mode 100644
index 0000000..10ecb1e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractExtensibleLogicalOperator.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+
+/**
+ * @author rico
+ */
+public abstract class AbstractExtensibleLogicalOperator implements IOperatorExtension {
+
+    private AbstractLogicalOperator.ExecutionMode mode = AbstractLogicalOperator.ExecutionMode.UNPARTITIONED;
+    protected List<LogicalVariable> schema;
+    protected IPhysicalOperator physicalOperator;
+
+    @Override
+    public ExecutionMode getExecutionMode() {
+        return mode;
+    }
+
+    @Override
+    public void setExecutionMode(ExecutionMode mode) {
+        this.mode = mode;
+    }
+
+    @Override
+    public void setSchema(List<LogicalVariable> schema) {
+        this.schema = schema;
+    }
+
+    @Override
+    public IPhysicalOperator getPhysicalOperator() {
+        return physicalOperator;
+    }
+
+    @Override
+    public void setPhysicalOperator(IPhysicalOperator physicalOperator) {
+        this.physicalOperator = physicalOperator;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java
new file mode 100644
index 0000000..dc0edfe
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java
@@ -0,0 +1,185 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+
+public abstract class AbstractLogicalOperator implements ILogicalOperator {
+
+    /*********************************************************************
+     * UNPARTITIONED, the input data is not partitioned
+     * PARTITIONED, the input data is partitioned, the operator is executed on
+     * each partition and may receive input from other partitions (e.g. if it is
+     * a join or an aggregate)
+     * LOCAL, the input data is partitioned, the operator is executed on each
+     * partition and only processes data from that partition
+     */
+
+    public static enum ExecutionMode {
+        UNPARTITIONED,
+        PARTITIONED,
+        LOCAL
+    }
+
+    private AbstractLogicalOperator.ExecutionMode mode = AbstractLogicalOperator.ExecutionMode.UNPARTITIONED;
+    protected IPhysicalOperator physicalOperator;
+    private final Map<String, Object> annotations = new HashMap<String, Object>();
+    private boolean bJobGenEnabled = true;
+
+    final protected List<Mutable<ILogicalOperator>> inputs;
+    // protected List<LogicalOperatorReference> outputs;
+    protected List<LogicalVariable> schema;
+
+    public AbstractLogicalOperator() {
+        inputs = new ArrayList<Mutable<ILogicalOperator>>();
+        // outputs = new ArrayList<LogicalOperatorReference>();
+    }
+
+    public abstract LogicalOperatorTag getOperatorTag();
+
+    public ExecutionMode getExecutionMode() {
+        return mode;
+    }
+
+    public void setExecutionMode(ExecutionMode mode) {
+        this.mode = mode;
+    }
+
+    @Override
+    public List<LogicalVariable> getSchema() {
+        return schema;
+    }
+
+    public void setPhysicalOperator(IPhysicalOperator physicalOp) {
+        this.physicalOperator = physicalOp;
+    }
+
+    public IPhysicalOperator getPhysicalOperator() {
+        return physicalOperator;
+    }
+
+    /**
+     * @return for each child, one vector of required physical properties
+     */
+
+    @Override
+    public final PhysicalRequirements getRequiredPhysicalPropertiesForChildren(
+            IPhysicalPropertiesVector requiredProperties) {
+        return physicalOperator.getRequiredPropertiesForChildren(this, requiredProperties);
+    }
+
+    /**
+     * @return the physical properties that this operator delivers, based on
+     *         what its children deliver
+     */
+
+    @Override
+    public final IPhysicalPropertiesVector getDeliveredPhysicalProperties() {
+        return physicalOperator.getDeliveredProperties();
+    }
+
+    @Override
+    public final void computeDeliveredPhysicalProperties(IOptimizationContext context) throws AlgebricksException {
+        physicalOperator.computeDeliveredProperties(this, context);
+    }
+
+    @Override
+    public final List<Mutable<ILogicalOperator>> getInputs() {
+        return inputs;
+    }
+
+    // @Override
+    // public final List<LogicalOperatorReference> getOutputs() {
+    // return outputs;
+    // }
+
+    @Override
+    public final boolean hasInputs() {
+        return !inputs.isEmpty();
+    }
+
+    public boolean hasNestedPlans() {
+        return false;
+    }
+
+    @Override
+    public Map<String, Object> getAnnotations() {
+        return annotations;
+    }
+
+    @Override
+    public void removeAnnotation(String annotationName) {
+        annotations.remove(annotationName);
+    }
+
+    @Override
+    public final void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        if (bJobGenEnabled) {
+            if (physicalOperator == null) {
+                throw new AlgebricksException("Physical operator not set for operator: " + this);
+            }
+            physicalOperator.contributeRuntimeOperator(builder, context, this, propagatedSchema, inputSchemas,
+                    outerPlanSchema);
+        }
+    }
+
+    public void disableJobGen() {
+        bJobGenEnabled = false;
+    }
+
+    public boolean isJobGenEnabled() {
+        return bJobGenEnabled;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeInputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+    protected IVariableTypeEnvironment createPropagatingAllInputsTypeEnvironment(ITypingContext ctx) {
+        //        return createPropagatingAllInputsTypeEnvironment(ctx);
+        int n = inputs.size();
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[n];
+        for (int i = 0; i < n; i++) {
+            envPointers[i] = new OpRefTypeEnvPointer(inputs.get(i), ctx);
+        }
+        return new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getNullableTypeComputer(),
+                ctx.getMetadataProvider(), TypePropagationPolicy.ALL, envPointers);
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractOperatorWithNestedPlans.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractOperatorWithNestedPlans.java
new file mode 100644
index 0000000..ea4f3e0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractOperatorWithNestedPlans.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public abstract class AbstractOperatorWithNestedPlans extends AbstractLogicalOperator {
+    protected final List<ILogicalPlan> nestedPlans;
+
+    public AbstractOperatorWithNestedPlans() {
+        nestedPlans = new ArrayList<ILogicalPlan>();
+    }
+
+    public AbstractOperatorWithNestedPlans(List<ILogicalPlan> nestedPlans) {
+        this.nestedPlans = nestedPlans;
+    }
+
+    public List<ILogicalPlan> getNestedPlans() {
+        return nestedPlans;
+    }
+
+    @Override
+    public boolean hasNestedPlans() {
+        return true;
+    }
+
+    public LinkedList<Mutable<ILogicalOperator>> allRootsInReverseOrder() {
+        LinkedList<Mutable<ILogicalOperator>> allRoots = new LinkedList<Mutable<ILogicalOperator>>();
+        for (ILogicalPlan p : nestedPlans) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                allRoots.addFirst(r);
+            }
+        }
+        return allRoots;
+    }
+
+    //
+    // @Override
+    // public void computeConstraintsAndEquivClasses() {
+    // for (ILogicalPlan p : nestedPlans) {
+    // for (LogicalOperatorReference r : p.getRoots()) {
+    // AbstractLogicalOperator op = (AbstractLogicalOperator) r.getOperator();
+    // equivalenceClasses.putAll(op.getEquivalenceClasses());
+    // functionalDependencies.addAll(op.getFDs());
+    // }
+    // }
+    // }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+        for (ILogicalPlan p : nestedPlans) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                schema.addAll(r.getValue().getSchema());
+            }
+        }
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    public abstract void getUsedVariablesExceptNestedPlans(Collection<LogicalVariable> vars);
+
+    public abstract void getProducedVariablesExceptNestedPlans(Collection<LogicalVariable> vars);
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractScanOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractScanOperator.java
new file mode 100644
index 0000000..4d8cce0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractScanOperator.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+
+public abstract class AbstractScanOperator extends AbstractLogicalOperator {
+    protected List<LogicalVariable> variables;
+
+    public AbstractScanOperator(List<LogicalVariable> variables) {
+        this.variables = variables;
+    }
+
+    public List<LogicalVariable> getVariables() {
+        return variables;
+    }
+
+    public void setVariables(List<LogicalVariable> variables) {
+        this.variables = variables;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+        schema.addAll(variables);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                if (sources.length > 0) {
+                    target.addAllVariables(sources[0]);
+                }
+                for (LogicalVariable v : variables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractUnnestOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractUnnestOperator.java
new file mode 100644
index 0000000..9eaf059
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractUnnestOperator.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+
+public abstract class AbstractUnnestOperator extends AbstractScanOperator {
+
+    protected final Mutable<ILogicalExpression> expression;
+
+    public AbstractUnnestOperator(List<LogicalVariable> variables, Mutable<ILogicalExpression> expression) {
+        super(variables);
+        this.expression = expression;
+    }
+
+    public Mutable<ILogicalExpression> getExpressionRef() {
+        return expression;
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return visitor.transform(expression);
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AggregateOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AggregateOperator.java
new file mode 100644
index 0000000..2f53f9b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AggregateOperator.java
@@ -0,0 +1,93 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.NonPropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class AggregateOperator extends AbstractAssignOperator {
+
+    // private ArrayList<AggregateFunctionCallExpression> expressions;
+    // TODO type safe list of expressions
+    private List<Mutable<ILogicalExpression>> mergeExpressions;
+    private LogicalVariable partitioningVariable;
+
+    public AggregateOperator(List<LogicalVariable> variables, List<Mutable<ILogicalExpression>> expressions) {
+        super(variables, expressions);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.AGGREGATE;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitAggregateOperator(this, arg);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                for (LogicalVariable v : variables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(variables);
+    }
+
+    public void setMergeExpressions(List<Mutable<ILogicalExpression>> merges) {
+        mergeExpressions = merges;
+    }
+
+    public List<Mutable<ILogicalExpression>> getMergeExpressions() {
+        return mergeExpressions;
+    }
+
+    public void setPartitioningVariable(LogicalVariable partitioningVariable) {
+        this.partitioningVariable = partitioningVariable;
+    }
+
+    public LogicalVariable getPartitioningVariable() {
+        return partitioningVariable;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = new NonPropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getMetadataProvider());
+        IVariableTypeEnvironment env2 = ctx.getOutputTypeEnvironment(inputs.get(0).getValue());
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            Object t = ctx.getExpressionTypeComputer().getType(expressions.get(i).getValue(),
+                    ctx.getMetadataProvider(), env2);
+            env.setVarType(variables.get(i), t);
+        }
+        return env;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java
new file mode 100644
index 0000000..a4dc2e0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+/**
+ * It corresponds to the Map operator in other algebras.
+ * 
+ * @author Nicola
+ */
+
+public class AssignOperator extends AbstractAssignOperator {
+
+    public AssignOperator(List<LogicalVariable> vars, List<Mutable<ILogicalExpression>> exprs) {
+        super(vars, exprs);
+    }
+
+    public AssignOperator(LogicalVariable var, Mutable<ILogicalExpression> expr) {
+        super();
+        this.variables.add(var);
+        this.expressions.add(expr);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.ASSIGN;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitAssignOperator(this, arg);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                target.addAllVariables(sources[0]);
+                for (LogicalVariable v : variables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = createPropagatingAllInputsTypeEnvironment(ctx);
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            env.setVarType(
+                    variables.get(i),
+                    ctx.getExpressionTypeComputer().getType(expressions.get(i).getValue(), ctx.getMetadataProvider(),
+                            env));
+        }
+        return env;
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java
new file mode 100644
index 0000000..3227f3d
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java
@@ -0,0 +1,110 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class DataSourceScanOperator extends AbstractScanOperator {
+    private IDataSource<?> dataSource;
+
+    private List<LogicalVariable> projectVars;
+
+    private boolean projectPushed = false;
+
+    public DataSourceScanOperator(List<LogicalVariable> variables, IDataSource<?> dataSource) {
+        super(variables);
+        this.dataSource = dataSource;
+        projectVars = new ArrayList<LogicalVariable>();
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.DATASOURCESCAN;
+    }
+
+    public IDataSource<?> getDataSource() {
+        return dataSource;
+    }
+
+    @Override
+    public <R, S> R accept(ILogicalOperatorVisitor<R, S> visitor, S arg) throws AlgebricksException {
+        return visitor.visitDataScanOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    public void addProjectVariables(Collection<LogicalVariable> vars) {
+        projectVars.addAll(vars);
+        projectPushed = true;
+    }
+
+    public List<LogicalVariable> getProjectVariables() {
+        return projectVars;
+    }
+
+    public boolean isProjectPushed() {
+        return projectPushed;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                if (sources.length > 0) {
+                    target.addAllVariables(sources[0]);
+                }
+                List<LogicalVariable> outputVariables = projectPushed ? projectVars : variables;
+                for (LogicalVariable v : outputVariables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = createPropagatingAllInputsTypeEnvironment(ctx);
+        Object[] types = dataSource.getSchemaTypes();
+        int i = 0;
+        for (LogicalVariable v : variables) {
+            env.setVarType(v, types[i]);
+            ++i;
+        }
+        return env;
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java
new file mode 100644
index 0000000..20aa574
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class DieOperator extends AbstractLogicalOperator {
+
+    private final Mutable<ILogicalExpression> afterObjects; // mandatory
+
+    public DieOperator(ILogicalExpression maxObjectsExpr) {
+        this.afterObjects = new MutableObject<ILogicalExpression>(maxObjectsExpr);
+    }
+
+    public Mutable<ILogicalExpression> getAfterObjects() {
+        return afterObjects;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitDieOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        if (visitor.transform(afterObjects)) {
+            b = true;
+        }
+        return b;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.DIE;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java
new file mode 100644
index 0000000..ee0dcf6
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class DistinctOperator extends AbstractLogicalOperator {
+    private final List<Mutable<ILogicalExpression>> expressions;
+
+    public DistinctOperator(List<Mutable<ILogicalExpression>> expressions) {
+        this.expressions = expressions;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.DISTINCT;
+    }
+
+    public List<Mutable<ILogicalExpression>> getExpressions() {
+        return expressions;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean changed = false;
+        for (Mutable<ILogicalExpression> e : expressions) {
+            if (visitor.transform(e)) {
+                changed = true;
+            }
+        }
+        return changed;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitDistinctOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    public List<LogicalVariable> getDistinctByVarList() {
+        List<LogicalVariable> varList = new ArrayList<LogicalVariable>(expressions.size());
+        for (Mutable<ILogicalExpression> eRef : expressions) {
+            ILogicalExpression e = eRef.getValue();
+            if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) e;
+                varList.add(v.getVariableReference());
+            }
+        }
+        return varList;
+    }
+
+    public boolean isDistinctByVar(LogicalVariable var) {
+        for (Mutable<ILogicalExpression> eRef : expressions) {
+            ILogicalExpression e = eRef.getValue();
+            if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) e;
+                if (v.getVariableReference() == var) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/EmptyTupleSourceOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/EmptyTupleSourceOperator.java
new file mode 100644
index 0000000..45f9909
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/EmptyTupleSourceOperator.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class EmptyTupleSourceOperator extends AbstractLogicalOperator {
+
+    // public final static EmptyTupleSourceOperator INSTANCE = new
+    // EmptyTupleSourceOperator();
+
+    public EmptyTupleSourceOperator() {
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.EMPTYTUPLESOURCE;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.NONE;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) {
+        // do nothing
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitEmptyTupleSourceOperator(this, arg);
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(final ITypingContext ctx) throws AlgebricksException {
+        return new IVariableTypeEnvironment() {
+
+            @Override
+            public void setVarType(LogicalVariable var, Object type) {
+                throw new IllegalStateException();
+            }
+
+            @Override
+            public Object getVarType(LogicalVariable var) throws AlgebricksException {
+                return null;
+            }
+
+            @Override
+            public Object getType(ILogicalExpression expr) throws AlgebricksException {
+                return ctx.getExpressionTypeComputer().getType(expr, ctx.getMetadataProvider(), this);
+            }
+
+            @Override
+            public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariables)
+                    throws AlgebricksException {
+                return null;
+            }
+
+            @Override
+            public boolean substituteProducedVariable(LogicalVariable v1, LogicalVariable v2)
+                    throws AlgebricksException {
+                return false;
+            }
+        };
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExchangeOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExchangeOperator.java
new file mode 100644
index 0000000..aba5f83
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExchangeOperator.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.util.OperatorPropertiesUtil;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class ExchangeOperator extends AbstractLogicalOperator {
+
+    public ExchangeOperator() {
+        super();
+        setExecutionMode(AbstractLogicalOperator.ExecutionMode.PARTITIONED);
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitExchangeOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) {
+        // do nothing
+        return false;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.EXCHANGE;
+    }
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        AbstractLogicalOperator cld = (AbstractLogicalOperator) inputs.get(0).getValue();
+        OperatorPropertiesUtil.computeSchemaRecIfNull(cld);
+        List<LogicalVariable> inputSchema = inputs.get(0).getValue().getSchema();
+        schema = new ArrayList<LogicalVariable>(inputSchema);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java
new file mode 100644
index 0000000..101b6f5
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+/**
+ * @author rico
+ */
+public class ExtensionOperator extends AbstractLogicalOperator {
+
+    private IOperatorExtension delegate;
+
+    public ExtensionOperator(IOperatorExtension delegate) {
+        super();
+        if (delegate == null) {
+            throw new IllegalArgumentException("delegate cannot be null!");
+        }
+        this.delegate = delegate;
+        setExecutionMode(delegate.getExecutionMode());
+    }
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+        delegate.setSchema(schema);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitExtensionOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return this.delegate.isMap();
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return this.createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.EXTENSION_OPERATOR;
+    }
+
+    public IOperatorExtension getNewInstanceOfDelegateOperator() {
+        return delegate.newInstance();
+    }
+
+    @Override
+    public List<LogicalVariable> getSchema() {
+        return this.schema;
+    }
+
+    @Override
+    public ExecutionMode getExecutionMode() {
+        return delegate.getExecutionMode();
+    }
+
+    @Override
+    public void setExecutionMode(ExecutionMode mode) {
+        delegate.setExecutionMode(mode);
+    }
+
+    @Override
+    public IPhysicalOperator getPhysicalOperator() {
+        return delegate.getPhysicalOperator();
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeInputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return this.createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/GroupByOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/GroupByOperator.java
new file mode 100644
index 0000000..ba396f4
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/GroupByOperator.java
@@ -0,0 +1,277 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class GroupByOperator extends AbstractOperatorWithNestedPlans {
+    // If the LogicalVariable in a pair is null, it means that the GroupBy is
+    // only grouping by the expression, without producing a new variable.
+    private final List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> gByList;
+    private final List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> decorList;
+
+    // In decorList, if the variable (first member of the pair) is null, the
+    // second member of the pair is variable reference which is propagated.
+
+    public GroupByOperator() {
+        super();
+        gByList = new ArrayList<Pair<LogicalVariable, Mutable<ILogicalExpression>>>();
+        decorList = new ArrayList<Pair<LogicalVariable, Mutable<ILogicalExpression>>>();
+    }
+
+    public GroupByOperator(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> groupByList,
+            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> decorList, List<ILogicalPlan> nestedPlans) {
+        super(nestedPlans);
+        this.decorList = decorList;
+        this.gByList = groupByList;
+    }
+
+    public void addGbyExpression(LogicalVariable variable, ILogicalExpression expression) {
+        this.gByList.add(new Pair<LogicalVariable, Mutable<ILogicalExpression>>(variable,
+                new MutableObject<ILogicalExpression>(expression)));
+    }
+
+    public void addDecorExpression(LogicalVariable variable, ILogicalExpression expression) {
+        this.decorList.add(new Pair<LogicalVariable, Mutable<ILogicalExpression>>(variable,
+                new MutableObject<ILogicalExpression>(expression)));
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.GROUP;
+    }
+
+    public List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> getGroupByList() {
+        return gByList;
+    }
+
+    public String gByListToString() {
+        return veListToString(gByList);
+    }
+
+    public String decorListToString() {
+        return veListToString(decorList);
+    }
+
+    public List<LogicalVariable> getGbyVarList() {
+        List<LogicalVariable> varList = new ArrayList<LogicalVariable>(gByList.size());
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : gByList) {
+            ILogicalExpression expr = ve.second.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) expr;
+                varList.add(v.getVariableReference());
+            }
+        }
+        return varList;
+    }
+
+    public static String veListToString(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> vePairList) {
+        StringBuilder sb = new StringBuilder();
+        sb.append("[");
+        boolean fst = true;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : vePairList) {
+            if (fst) {
+                fst = false;
+            } else {
+                sb.append("; ");
+            }
+            if (ve.first != null) {
+                sb.append(ve.first + " := " + ve.second);
+            } else {
+                sb.append(ve.second.getValue());
+            }
+        }
+        sb.append("]");
+        return sb.toString();
+    }
+
+    @Override
+    public void recomputeSchema() {
+        super.recomputeSchema();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            schema.add(p.first);
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : decorList) {
+            schema.add(getDecorVariable(p));
+        }
+    }
+
+    @Override
+    public void getProducedVariablesExceptNestedPlans(Collection<LogicalVariable> vars) {
+        // super.getProducedVariables(vars);
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            if (p.first != null) {
+                vars.add(p.first);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : decorList) {
+            if (p.first != null) {
+                vars.add(p.first);
+            }
+        }
+    }
+
+    @Override
+    public void getUsedVariablesExceptNestedPlans(Collection<LogicalVariable> vars) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> g : gByList) {
+            g.second.getValue().getUsedVariables(vars);
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> g : decorList) {
+            g.second.getValue().getUsedVariables(vars);
+        }
+        // super.getUsedVariables(vars);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+                    ILogicalExpression expr = p.second.getValue();
+                    if (p.first != null) {
+                        target.addVariable(p.first);
+                    } else {
+                        if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                            throw new AlgebricksException("hash group-by expects variable references.");
+                        }
+                        VariableReferenceExpression v = (VariableReferenceExpression) expr;
+                        target.addVariable(v.getVariableReference());
+                    }
+                }
+                for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : decorList) {
+                    ILogicalExpression expr = p.second.getValue();
+                    if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                        throw new AlgebricksException("pre-sorted group-by expects variable references.");
+                    }
+                    VariableReferenceExpression v = (VariableReferenceExpression) expr;
+                    LogicalVariable decor = v.getVariableReference();
+                    if (p.first != null) {
+                        target.addVariable(p.first);
+                    } else {
+                        target.addVariable(decor);
+                    }
+                }
+
+            }
+        };
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            if (visitor.transform(p.second)) {
+                b = true;
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : decorList) {
+            if (visitor.transform(p.second)) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitGroupByOperator(this, arg);
+    }
+
+    public static LogicalVariable getDecorVariable(Pair<LogicalVariable, Mutable<ILogicalExpression>> p) {
+        if (p.first != null) {
+            return p.first;
+        } else {
+            VariableReferenceExpression e = (VariableReferenceExpression) p.second.getValue();
+            return e.getVariableReference();
+        }
+    }
+
+    public List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> getDecorList() {
+        return decorList;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        int n = 0;
+        for (ILogicalPlan p : nestedPlans) {
+            n += p.getRoots().size();
+        }
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[n];
+        int i = 0;
+        for (ILogicalPlan p : nestedPlans) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                envPointers[i] = new OpRefTypeEnvPointer(r, ctx);
+                i++;
+            }
+        }
+        IVariableTypeEnvironment env = new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getNullableTypeComputer(), ctx.getMetadataProvider(), TypePropagationPolicy.ALL, envPointers);
+        ILogicalOperator child = inputs.get(0).getValue();
+        IVariableTypeEnvironment env2 = ctx.getOutputTypeEnvironment(child);
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : getGroupByList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (p.first != null) {
+                env.setVarType(p.first, env2.getType(expr));
+                if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                    LogicalVariable v1 = ((VariableReferenceExpression) expr).getVariableReference();
+                    env.setVarType(v1, env2.getVarType(v1));
+                }
+            } else {
+                VariableReferenceExpression vre = (VariableReferenceExpression) p.second.getValue();
+                LogicalVariable v2 = vre.getVariableReference();
+                env.setVarType(v2, env2.getVarType(v2));
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : getDecorList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (p.first != null) {
+                env.setVarType(p.first, env2.getType(expr));
+            } else {
+                VariableReferenceExpression vre = (VariableReferenceExpression) p.second.getValue();
+                LogicalVariable v2 = vre.getVariableReference();
+                env.setVarType(v2, env2.getVarType(v2));
+            }
+        }
+        return env;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java
new file mode 100644
index 0000000..98c3301
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+
+/**
+ * @author rico
+ */
+public interface IOperatorExtension {
+
+    void setExecutionMode(ExecutionMode mode);
+
+    boolean isMap();
+
+    public IOperatorExtension newInstance();
+
+    boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException;
+
+    void setSchema(List<LogicalVariable> schema);
+
+    IPhysicalOperator getPhysicalOperator();
+
+    void setPhysicalOperator(IPhysicalOperator physicalOperator);
+
+    ExecutionMode getExecutionMode();
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorSchema.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorSchema.java
new file mode 100644
index 0000000..043ac8e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorSchema.java
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IOperatorSchema extends Iterable<LogicalVariable> {
+    public void addAllVariables(IOperatorSchema source);
+
+    public void addAllNewVariables(IOperatorSchema source);
+
+    public int addVariable(LogicalVariable var);
+
+    public int findVariable(LogicalVariable var);
+
+    public LogicalVariable getVariable(int index);
+
+    public int getSize();
+
+    public void clear();
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IndexInsertDeleteOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IndexInsertDeleteOperator.java
new file mode 100644
index 0000000..becde1c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IndexInsertDeleteOperator.java
@@ -0,0 +1,105 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSourceIndex;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator.Kind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class IndexInsertDeleteOperator extends AbstractLogicalOperator {
+
+    private final IDataSourceIndex<?, ?> dataSourceIndex;
+    private final List<Mutable<ILogicalExpression>> primaryKeyExprs;
+    private final List<Mutable<ILogicalExpression>> secondaryKeyExprs;
+    private final Mutable<ILogicalExpression> filterExpr;
+    private final Kind operation;
+
+    public IndexInsertDeleteOperator(IDataSourceIndex<?, ?> dataSourceIndex,
+            List<Mutable<ILogicalExpression>> primaryKeyExprs, List<Mutable<ILogicalExpression>> secondaryKeyExprs,
+            Mutable<ILogicalExpression> filterExpr, Kind operation) {
+        this.dataSourceIndex = dataSourceIndex;
+        this.primaryKeyExprs = primaryKeyExprs;
+        this.secondaryKeyExprs = secondaryKeyExprs;
+        this.filterExpr = filterExpr;
+        this.operation = operation;
+    }
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        for (int i = 0; i < primaryKeyExprs.size(); i++) {
+            if (visitor.transform(primaryKeyExprs.get(i))) {
+                b = true;
+            }
+        }
+        for (int i = 0; i < secondaryKeyExprs.size(); i++) {
+            if (visitor.transform(secondaryKeyExprs.get(i))) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitIndexInsertDeleteOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.INDEX_INSERT_DELETE;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+    public List<Mutable<ILogicalExpression>> getPrimaryKeyExpressions() {
+        return primaryKeyExprs;
+    }
+
+    public IDataSourceIndex<?, ?> getDataSourceIndex() {
+        return dataSourceIndex;
+    }
+
+    public List<Mutable<ILogicalExpression>> getSecondaryKeyExpressions() {
+        return secondaryKeyExprs;
+    }
+
+    public Mutable<ILogicalExpression> getFilterExpression() {
+    	return filterExpr;
+    }
+    
+    public Kind getOperation() {
+        return operation;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InnerJoinOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InnerJoinOperator.java
new file mode 100644
index 0000000..54fab7c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InnerJoinOperator.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class InnerJoinOperator extends AbstractBinaryJoinOperator {
+
+    public InnerJoinOperator(Mutable<ILogicalExpression> condition) {
+        super(JoinKind.INNER, condition);
+    }
+
+    public InnerJoinOperator(Mutable<ILogicalExpression> condition, Mutable<ILogicalOperator> input1,
+            Mutable<ILogicalOperator> input2) {
+        super(JoinKind.INNER, condition, input1, input2);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.INNERJOIN;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitInnerJoinOperator(this, arg);
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InsertDeleteOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InsertDeleteOperator.java
new file mode 100644
index 0000000..91e51f6
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/InsertDeleteOperator.java
@@ -0,0 +1,98 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class InsertDeleteOperator extends AbstractLogicalOperator {
+
+    public enum Kind {
+        INSERT,
+        DELETE
+    }
+
+    private final IDataSource<?> dataSource;
+    private final Mutable<ILogicalExpression> payloadExpr;
+    private final List<Mutable<ILogicalExpression>> primaryKeyExprs;
+    private final Kind operation;
+
+    public InsertDeleteOperator(IDataSource<?> dataSource, Mutable<ILogicalExpression> payload,
+            List<Mutable<ILogicalExpression>> primaryKeyExprs, Kind operation) {
+        this.dataSource = dataSource;
+        this.payloadExpr = payload;
+        this.primaryKeyExprs = primaryKeyExprs;
+        this.operation = operation;
+    }
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        b = visitor.transform(payloadExpr);
+        for (int i = 0; i < primaryKeyExprs.size(); i++) {
+            if (visitor.transform(primaryKeyExprs.get(i))) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitInsertDeleteOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.INSERT_DELETE;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+    public List<Mutable<ILogicalExpression>> getPrimaryKeyExpressions() {
+        return primaryKeyExprs;
+    }
+
+    public IDataSource<?> getDataSource() {
+        return dataSource;
+    }
+
+    public Mutable<ILogicalExpression> getPayloadExpression() {
+        return payloadExpr;
+    }
+
+    public Kind getOperation() {
+        return operation;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LeftOuterJoinOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LeftOuterJoinOperator.java
new file mode 100644
index 0000000..60da2cf
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LeftOuterJoinOperator.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class LeftOuterJoinOperator extends AbstractBinaryJoinOperator {
+
+    public LeftOuterJoinOperator(Mutable<ILogicalExpression> condition) {
+        super(JoinKind.LEFT_OUTER, condition);
+    }
+
+    public LeftOuterJoinOperator(Mutable<ILogicalExpression> condition, Mutable<ILogicalOperator> input1,
+            Mutable<ILogicalOperator> input2) {
+        super(JoinKind.LEFT_OUTER, condition, input1, input2);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.LEFTOUTERJOIN;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitLeftOuterJoinOperator(this, arg);
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        int n = inputs.size();
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[n];
+        for (int i = 0; i < n; i++) {
+            envPointers[i] = new OpRefTypeEnvPointer(inputs.get(i), ctx);
+        }
+        return new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getNullableTypeComputer(),
+                ctx.getMetadataProvider(), TypePropagationPolicy.LEFT_OUTER, envPointers);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java
new file mode 100644
index 0000000..3c6a699
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class LimitOperator extends AbstractLogicalOperator {
+
+    private final Mutable<ILogicalExpression> maxObjects; // mandatory
+    private final Mutable<ILogicalExpression> offset; // optional
+    private boolean topmost;
+
+    public LimitOperator(ILogicalExpression maxObjectsExpr, ILogicalExpression offsetExpr, boolean topmost) {
+        this.maxObjects = new MutableObject<ILogicalExpression>(maxObjectsExpr);
+        this.offset = new MutableObject<ILogicalExpression>(offsetExpr);
+        this.topmost = topmost;
+    }
+
+    public LimitOperator(ILogicalExpression maxObjectsExpr, boolean topmost) {
+        this(maxObjectsExpr, null, topmost);
+    }
+
+    public LimitOperator(ILogicalExpression maxObjects, ILogicalExpression offset) {
+        this(maxObjects, offset, true);
+    }
+
+    public LimitOperator(ILogicalExpression maxObjects) {
+        this(maxObjects, null, true);
+    }
+
+    public Mutable<ILogicalExpression> getMaxObjects() {
+        return maxObjects;
+    }
+
+    public Mutable<ILogicalExpression> getOffset() {
+        return offset;
+    }
+
+    public boolean isTopmostLimitOp() {
+        return topmost;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitLimitOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        if (visitor.transform(maxObjects)) {
+            b = true;
+        }
+        if (offset.getValue() != null) {
+            if (visitor.transform(offset)) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.LIMIT;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/NestedTupleSourceOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/NestedTupleSourceOperator.java
new file mode 100644
index 0000000..a9a8f55
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/NestedTupleSourceOperator.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class NestedTupleSourceOperator extends AbstractLogicalOperator {
+    private final Mutable<ILogicalOperator> dataSourceReference;
+
+    public NestedTupleSourceOperator(Mutable<ILogicalOperator> dataSourceReference) {
+        this.dataSourceReference = dataSourceReference;
+    }
+
+    public ILogicalOperator getSourceOperator() {
+        return dataSourceReference.getValue().getInputs().get(0).getValue();
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.NESTEDTUPLESOURCE;
+    }
+
+    public Mutable<ILogicalOperator> getDataSourceReference() {
+        return dataSourceReference;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        ILogicalOperator topOp = dataSourceReference.getValue();
+        for (Mutable<ILogicalOperator> i : topOp.getInputs()) {
+            schema.addAll(i.getValue().getSchema());
+        }
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) {
+        // do nothing
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitNestedTupleSourceOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(final ITypingContext ctx) throws AlgebricksException {
+        ITypeEnvPointer[] p = new ITypeEnvPointer[1];
+        p[0] = new ITypeEnvPointer() {
+
+            @Override
+            public IVariableTypeEnvironment getTypeEnv() {
+                ILogicalOperator op = dataSourceReference.getValue().getInputs().get(0).getValue();
+                return ctx.getOutputTypeEnvironment(op);
+            }
+        };
+        return new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getNullableTypeComputer(),
+                ctx.getMetadataProvider(), TypePropagationPolicy.ALL, p);
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeInputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return computeOutputTypeEnvironment(ctx);
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/OrderOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/OrderOperator.java
new file mode 100644
index 0000000..812c219
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/OrderOperator.java
@@ -0,0 +1,159 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class OrderOperator extends AbstractLogicalOperator {
+
+    public interface IOrder {
+        public enum OrderKind {
+            FUNCTIONCALL,
+            ASC,
+            DESC
+        };
+
+        public Mutable<ILogicalExpression> getExpressionRef();
+
+        public OrderKind getKind();
+    }
+
+    public static IOrder ASC_ORDER = new IOrder() {
+
+        @Override
+        public Mutable<ILogicalExpression> getExpressionRef() {
+            return null;
+        }
+
+        @Override
+        public OrderKind getKind() {
+            return OrderKind.ASC;
+        }
+
+    };
+
+    public static IOrder DESC_ORDER = new IOrder() {
+
+        @Override
+        public Mutable<ILogicalExpression> getExpressionRef() {
+            return null;
+        }
+
+        @Override
+        public OrderKind getKind() {
+            return OrderKind.DESC;
+        }
+    };
+
+    public class FunOrder implements IOrder {
+        private final Mutable<ILogicalExpression> f;
+
+        public FunOrder(Mutable<ILogicalExpression> f) {
+            this.f = f;
+        }
+
+        @Override
+        public Mutable<ILogicalExpression> getExpressionRef() {
+            return f;
+        }
+
+        @Override
+        public OrderKind getKind() {
+            return OrderKind.FUNCTIONCALL;
+        }
+
+    };
+
+    private final List<Pair<IOrder, Mutable<ILogicalExpression>>> orderExpressions;
+
+    // These are pairs of type (comparison, expr) where comparison is
+    // ASC or DESC or a boolean function of arity 2 that can take as
+    // arguments results of expr.
+
+    public OrderOperator() {
+        orderExpressions = new ArrayList<Pair<IOrder, Mutable<ILogicalExpression>>>();
+    }
+
+    public OrderOperator(List<Pair<IOrder, Mutable<ILogicalExpression>>> orderExpressions) {
+        this.orderExpressions = orderExpressions;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.ORDER;
+    }
+
+    public List<Pair<IOrder, Mutable<ILogicalExpression>>> getOrderExpressions() {
+        return orderExpressions;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        for (Pair<IOrder, Mutable<ILogicalExpression>> p : orderExpressions) {
+            if (p.first.getKind() == OrderKind.FUNCTIONCALL) {
+                FunOrder fo = (FunOrder) p.first;
+                Mutable<ILogicalExpression> r1 = fo.getExpressionRef();
+                if (visitor.transform(r1)) {
+                    b = true;
+                }
+            }
+            if (visitor.transform(p.second)) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitOrderOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/PartitioningSplitOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/PartitioningSplitOperator.java
new file mode 100644
index 0000000..6fe6bed
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/PartitioningSplitOperator.java
@@ -0,0 +1,115 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.PartitioningSplitOperatorDescriptor;
+
+/**
+ * Partitions it's input based on a given list of expressions.
+ * Each expression is assumed to return true/false,
+ * and there is exactly one output branch per expression (optionally, plus one default branch).
+ * For each input tuple, the expressions are evaluated one-by-one,
+ * and the tuple is written to first output branch whose corresponding
+ * expression evaluates to true.
+ * If all expressions evaluate to false, then
+ * the tuple is written to the default output branch, if any was given.
+ * If no output branch was given, then such tuples are simply dropped.
+ * Given N expressions there may be N or N+1 output branches because the default output branch may be separate from the regular output branches.
+ */
+public class PartitioningSplitOperator extends AbstractLogicalOperator {
+
+    private final List<Mutable<ILogicalExpression>> expressions;
+    private final int defaultBranchIndex;
+
+    public PartitioningSplitOperator(List<Mutable<ILogicalExpression>> expressions, int defaultBranchIndex) throws AlgebricksException {
+        this.expressions = expressions;
+        this.defaultBranchIndex = defaultBranchIndex;
+        // Check that the default output branch index is in [0, N], where N is the number of expressions.
+        if (defaultBranchIndex != PartitioningSplitOperatorDescriptor.NO_DEFAULT_BRANCH
+                && defaultBranchIndex > expressions.size()) {
+            throw new AlgebricksException("Default branch index out of bounds. Number of exprs given: "
+                    + expressions.size() + ". The maximum default branch index may therefore be: " + expressions.size());
+        }
+    }
+
+    public List<Mutable<ILogicalExpression>> getExpressions() {
+        return expressions;
+    }
+
+    public int getDefaultBranchIndex() {
+        return defaultBranchIndex;
+    }
+    
+    public int getNumOutputBranches() {
+        return (defaultBranchIndex == expressions.size()) ? expressions.size() + 1 : expressions.size();
+    }
+    
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.PARTITIONINGSPLIT;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = false;
+        for (int i = 0; i < expressions.size(); i++) {
+            if (visitor.transform(expressions.get(i))) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitPartitioningSplitOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ProjectOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ProjectOperator.java
new file mode 100644
index 0000000..459e5dd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ProjectOperator.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FilteredVariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class ProjectOperator extends AbstractLogicalOperator {
+
+    private final List<LogicalVariable> variables;
+
+    public ProjectOperator(List<LogicalVariable> variables) {
+        this.variables = variables;
+    }
+
+    public ProjectOperator(LogicalVariable v) {
+        this.variables = new ArrayList<LogicalVariable>(1);
+        this.getVariables().add(v);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) {
+        // do nothing
+        return false;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.PROJECT;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>(getVariables());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new FilteredVariablePropagationPolicy(getVariables());
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitProjectOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    public List<LogicalVariable> getVariables() {
+        return variables;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ReplicateOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ReplicateOperator.java
new file mode 100644
index 0000000..a4e9d2b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ReplicateOperator.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class ReplicateOperator extends AbstractLogicalOperator {
+
+    private int outputArity = 2;
+
+    public ReplicateOperator(int outputArity) {
+        this.outputArity = outputArity;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.REPLICATE;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitReplicateOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+    }
+
+    public void substituteVar(LogicalVariable v1, LogicalVariable v2) {
+        // do nothing
+    }
+
+    public int getOutputArity() {
+        return outputArity;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/RunningAggregateOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/RunningAggregateOperator.java
new file mode 100644
index 0000000..3694503
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/RunningAggregateOperator.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class RunningAggregateOperator extends AbstractAssignOperator {
+
+    public RunningAggregateOperator(List<LogicalVariable> variables, List<Mutable<ILogicalExpression>> expressions) {
+        super(variables, expressions);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.RUNNINGAGGREGATE;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitRunningAggregateOperator(this, arg);
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                target.addAllVariables(sources[0]);
+                for (LogicalVariable v : variables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = createPropagatingAllInputsTypeEnvironment(ctx);
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            env.setVarType(
+                    variables.get(i),
+                    ctx.getExpressionTypeComputer().getType(expressions.get(i).getValue(), ctx.getMetadataProvider(),
+                            env));
+        }
+        return env;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ScriptOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ScriptOperator.java
new file mode 100644
index 0000000..c75fb40
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ScriptOperator.java
@@ -0,0 +1,106 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.scripting.IScriptDescription;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.NonPropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class ScriptOperator extends AbstractLogicalOperator {
+
+    private ArrayList<LogicalVariable> inputVariables;
+    private ArrayList<LogicalVariable> outputVariables;
+    private IScriptDescription scriptDesc;
+
+    public ScriptOperator(IScriptDescription scriptDesc, ArrayList<LogicalVariable> inputVariables,
+            ArrayList<LogicalVariable> outputVariables) {
+        this.inputVariables = inputVariables;
+        this.outputVariables = outputVariables;
+        this.scriptDesc = scriptDesc;
+    }
+
+    public ArrayList<LogicalVariable> getInputVariables() {
+        return inputVariables;
+    }
+
+    public ArrayList<LogicalVariable> getOutputVariables() {
+        return outputVariables;
+    }
+
+    public IScriptDescription getScriptDescription() {
+        return scriptDesc;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.SCRIPT;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitScriptOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                for (LogicalVariable v : outputVariables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        this.schema = outputVariables;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = new NonPropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getMetadataProvider());
+        for (Pair<LogicalVariable, Object> p : scriptDesc.getVarTypePairs()) {
+            env.setVarType(p.first, p.second);
+        }
+        return env;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java
new file mode 100644
index 0000000..8c611b0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class SelectOperator extends AbstractLogicalOperator {
+    private final Mutable<ILogicalExpression> condition;
+
+    public SelectOperator(Mutable<ILogicalExpression> condition) {
+        this.condition = condition;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.SELECT;
+    }
+
+    public Mutable<ILogicalExpression> getCondition() {
+        return condition;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return visitor.transform(condition);
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitSelectOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return true;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[1];
+        envPointers[0] = new OpRefTypeEnvPointer(inputs.get(0), ctx);
+        PropagatingTypeEnvironment env = new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getNullableTypeComputer(), ctx.getMetadataProvider(), TypePropagationPolicy.ALL, envPointers);
+        if (condition.getValue().getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
+            AbstractFunctionCallExpression f1 = (AbstractFunctionCallExpression) condition.getValue();
+            if (f1.getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.NOT)) {
+                ILogicalExpression a1 = f1.getArguments().get(0).getValue();
+                if (a1.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
+                    AbstractFunctionCallExpression f2 = (AbstractFunctionCallExpression) a1;
+                    if (f2.getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.IS_NULL)) {
+                        ILogicalExpression a2 = f2.getArguments().get(0).getValue();
+                        if (a2.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                            LogicalVariable var = ((VariableReferenceExpression) a2).getVariableReference();
+                            env.getNonNullVariables().add(var);
+                        }
+                    }
+                }
+            }
+        }
+        return env;
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SinkOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SinkOperator.java
new file mode 100644
index 0000000..1b12423
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SinkOperator.java
@@ -0,0 +1,59 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class SinkOperator extends AbstractLogicalOperator {
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitSinkOperator(this, arg);
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[1];
+        envPointers[0] = new OpRefTypeEnvPointer(inputs.get(0), ctx);
+        PropagatingTypeEnvironment env = new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getNullableTypeComputer(), ctx.getMetadataProvider(), TypePropagationPolicy.ALL, envPointers);
+        return env;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.SINK;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SubplanOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SubplanOperator.java
new file mode 100644
index 0000000..89707eb
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SubplanOperator.java
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.plan.ALogicalPlanImpl;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.OpRefTypeEnvPointer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.PropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class SubplanOperator extends AbstractOperatorWithNestedPlans {
+
+    public SubplanOperator() {
+        super();
+    }
+
+    public SubplanOperator(List<ILogicalPlan> plans) {
+        super(plans);
+    }
+
+    public SubplanOperator(ILogicalOperator planRoot) {
+        ArrayList<Mutable<ILogicalOperator>> roots = new ArrayList<Mutable<ILogicalOperator>>(1);
+        roots.add(new MutableObject<ILogicalOperator>(planRoot));
+        nestedPlans.add(new ALogicalPlanImpl(roots));
+    }
+
+    public void setRootOp(Mutable<ILogicalOperator> opRef) {
+        ILogicalPlan p = new ALogicalPlanImpl(opRef);
+        nestedPlans.add(p);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) {
+        // do nothing
+        return false;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.SUBPLAN;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ADDNEWVARIABLES;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitSubplanOperator(this, arg);
+    }
+
+    @Override
+    public void getProducedVariablesExceptNestedPlans(Collection<LogicalVariable> vars) {
+        // do nothing
+    }
+
+    @Override
+    public void getUsedVariablesExceptNestedPlans(Collection<LogicalVariable> vars) {
+        // do nothing
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        int n = 0;
+        for (ILogicalPlan p : nestedPlans) {
+            n += p.getRoots().size();
+        }
+        ITypeEnvPointer[] envPointers = new ITypeEnvPointer[n + 1];
+        envPointers[0] = new OpRefTypeEnvPointer(inputs.get(0), ctx);
+        int i = 1;
+        for (ILogicalPlan p : nestedPlans) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                envPointers[i] = new OpRefTypeEnvPointer(r, ctx);
+                i++;
+            }
+        }
+        return new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getNullableTypeComputer(),
+                ctx.getMetadataProvider(), TypePropagationPolicy.LEFT_OUTER, envPointers);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnionAllOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnionAllOperator.java
new file mode 100644
index 0000000..c7100dd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnionAllOperator.java
@@ -0,0 +1,120 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.NonPropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class UnionAllOperator extends AbstractLogicalOperator {
+
+    // (left-var, right-var, out-var)
+    private List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> varMap;
+
+    public UnionAllOperator(List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> varMap) {
+        this.varMap = varMap;
+    }
+
+    public List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> getVariableMappings() {
+        return varMap;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.UNIONALL;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : varMap) {
+                    target.addVariable(t.third);
+                }
+            }
+        };
+
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitUnionOperator(this, arg);
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        for (LogicalVariable v1 : inputs.get(0).getValue().getSchema()) {
+            for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : varMap) {
+                if (t.first.equals(v1)) {
+                    schema.add(t.third);
+                } else {
+                    schema.add(v1);
+                }
+            }
+        }
+        for (LogicalVariable v2 : inputs.get(1).getValue().getSchema()) {
+            for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : varMap) {
+                if (t.second.equals(v2)) {
+                    schema.add(t.third);
+                } else {
+                    schema.add(v2);
+                }
+            }
+        }
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = new NonPropagatingTypeEnvironment(ctx.getExpressionTypeComputer(),
+                ctx.getMetadataProvider());
+        IVariableTypeEnvironment envLeft = ctx.getOutputTypeEnvironment(inputs.get(0).getValue());
+        if (envLeft == null) {
+            throw new AlgebricksException("Left input types for union operator are not computed.");
+        }
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : varMap) {
+            Object t1 = envLeft.getVarType(t.first);
+            if (t1 == null) {
+                throw new AlgebricksException("Failed typing union operator: no type for variable " + t.first);
+            }
+            env.setVarType(t.third, t1);
+        }
+        return env;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestMapOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestMapOperator.java
new file mode 100644
index 0000000..b9a137f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestMapOperator.java
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.NonPropagatingTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+/**
+ * This operator may go away after we add indexes to Algebricks.
+ */
+public class UnnestMapOperator extends AbstractUnnestOperator {
+
+    private final List<Object> variableTypes; // TODO: get rid of this and
+    private final boolean propagateInput;
+    
+    // deprecate UnnestMap
+
+    public UnnestMapOperator(List<LogicalVariable> variables, Mutable<ILogicalExpression> expression,
+            List<Object> variableTypes, boolean propagateInput) {
+        super(variables, expression);
+        this.variableTypes = variableTypes;
+        this.propagateInput = propagateInput;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.UNNEST_MAP;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitUnnestMapOperator(this, arg);
+    }
+
+    /**
+     * UnnestMap doesn't propagate input variables, because currently it is only
+     * used to search indexes. In the future, it would be nice to have the
+     * choice to propagate input variables or not.
+     */
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return new VariablePropagationPolicy() {
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                if (propagateInput) {
+                    target.addAllVariables(sources[0]);
+                }
+                for (LogicalVariable v : variables) {
+                    target.addVariable(v);
+                }
+            }
+        };
+    }
+
+    public List<Object> getVariableTypes() {
+        return variableTypes;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = null;
+        if (propagateInput) {
+            env = createPropagatingAllInputsTypeEnvironment(ctx);
+        } else {
+            env = new NonPropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getMetadataProvider());
+        }
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            env.setVarType(variables.get(i), variableTypes.get(i));
+        }
+        return env;
+    }
+    
+    public boolean propagatesInput() {
+        return propagateInput;
+    }
+    
+    /*
+    @Override
+    public boolean isMap() {
+        return !propagateInput;
+    }
+    */
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestOperator.java
new file mode 100644
index 0000000..2e1ef16
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UnnestOperator.java
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class UnnestOperator extends AbstractUnnestOperator {
+
+    private LogicalVariable positionalVariable;
+    private Object positionalVariableType;
+
+    public UnnestOperator(LogicalVariable variable, Mutable<ILogicalExpression> expression) {
+        super(makeSingletonList(variable), expression);
+    }
+
+    public UnnestOperator(LogicalVariable variable, Mutable<ILogicalExpression> expression,
+            LogicalVariable positionalVariable, Object positionalVariableType) {
+        this(variable, expression);
+        this.setPositionalVariable(positionalVariable);
+        this.setPositionalVariableType(positionalVariableType);
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.UNNEST;
+    }
+
+    public LogicalVariable getVariable() {
+        return variables.get(0);
+    }
+
+    public void setPositionalVariable(LogicalVariable positionalVariable) {
+        this.positionalVariable = positionalVariable;
+    }
+
+    public LogicalVariable getPositionalVariable() {
+        return positionalVariable;
+    }
+
+    public void setPositionalVariableType(Object positionalVariableType) {
+        this.positionalVariableType = positionalVariableType;
+    }
+
+    public Object getPositionalVariableType() {
+        return positionalVariableType;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitUnnestOperator(this, arg);
+    }
+
+    private static <E> ArrayList<E> makeSingletonList(E item) {
+        ArrayList<E> array = new ArrayList<E>(1);
+        array.add(item);
+        return array;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        IVariableTypeEnvironment env = createPropagatingAllInputsTypeEnvironment(ctx);
+        Object t = env.getType(expression.getValue());
+        env.setVarType(variables.get(0), t);
+        if (positionalVariable != null) {
+            env.setVarType(positionalVariable, positionalVariableType);
+        }
+        return env;
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UpdateOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UpdateOperator.java
new file mode 100644
index 0000000..f156490
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/UpdateOperator.java
@@ -0,0 +1,55 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class UpdateOperator extends AbstractLogicalOperator {
+
+    @Override
+    public void recomputeSchema() throws AlgebricksException {
+        // TODO Auto-generated method stub
+
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return false;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public boolean isMap() {
+        // TODO Auto-generated method stub
+        return false;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteOperator.java
new file mode 100644
index 0000000..4c14333
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteOperator.java
@@ -0,0 +1,93 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSink;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class WriteOperator extends AbstractLogicalOperator {
+    private List<Mutable<ILogicalExpression>> expressions;
+    private IDataSink dataSink;
+
+    public WriteOperator(List<Mutable<ILogicalExpression>> expressions, IDataSink dataSink) {
+        this.expressions = expressions;
+        this.dataSink = dataSink;
+    }
+
+    public List<Mutable<ILogicalExpression>> getExpressions() {
+        return expressions;
+    }
+
+    public IDataSink getDataSink() {
+        return dataSink;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.WRITE;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitWriteOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean modif = false;
+        for (int i = 0; i < expressions.size(); i++) {
+            boolean b = visitor.transform(expressions.get(i));
+            if (b) {
+                modif = true;
+            }
+        }
+        return modif;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return false; // actually depends on the physical op.
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteResultOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteResultOperator.java
new file mode 100644
index 0000000..48065a5
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/WriteResultOperator.java
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.VariablePropagationPolicy;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class WriteResultOperator extends AbstractLogicalOperator {
+
+    private IDataSource<?> dataSource;
+    private Mutable<ILogicalExpression> payloadExpr;
+    private List<Mutable<ILogicalExpression>> keyExprs;
+
+    public WriteResultOperator(IDataSource<?> dataSource, Mutable<ILogicalExpression> payload,
+            List<Mutable<ILogicalExpression>> keyExprs) {
+        this.dataSource = dataSource;
+        this.payloadExpr = payload;
+        this.keyExprs = keyExprs;
+    }
+
+    public IDataSource<?> getDataSource() {
+        return dataSource;
+    }
+
+    public Mutable<ILogicalExpression> getPayloadExpression() {
+        return payloadExpr;
+    }
+
+    public List<Mutable<ILogicalExpression>> getKeyExpressions() {
+        return keyExprs;
+    }
+
+    @Override
+    public LogicalOperatorTag getOperatorTag() {
+        return LogicalOperatorTag.WRITE_RESULT;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitWriteResultOperator(this, arg);
+    }
+
+    @Override
+    public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform visitor) throws AlgebricksException {
+        boolean b = visitor.transform(payloadExpr);
+        for (int i = 0; i < keyExprs.size(); i++) {
+            if (visitor.transform(keyExprs.get(i))) {
+                b = true;
+            }
+        }
+        return b;
+    }
+
+    @Override
+    public VariablePropagationPolicy getVariablePropagationPolicy() {
+        return VariablePropagationPolicy.ALL;
+    }
+
+    @Override
+    public boolean isMap() {
+        return false;
+    }
+
+    @Override
+    public void recomputeSchema() {
+        schema = new ArrayList<LogicalVariable>();
+        schema.addAll(inputs.get(0).getValue().getSchema());
+    }
+
+    @Override
+    public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
+        return createPropagatingAllInputsTypeEnvironment(ctx);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java
new file mode 100644
index 0000000..0539cbe
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java
@@ -0,0 +1,647 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression.FunctionKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractUnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalGroupingProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+import edu.uci.ics.hyracks.algebricks.core.config.AlgebricksConfig;
+
+public class FDsAndEquivClassesVisitor implements ILogicalOperatorVisitor<Void, IOptimizationContext> {
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        ctx.putEquivalenceClassMap(op, new HashMap<LogicalVariable, EquivalenceClass>());
+        ctx.putFDList(op, new ArrayList<FunctionalDependency>());
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        ILogicalOperator inp1 = op.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = getOrComputeEqClasses(inp1, ctx);
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<LogicalVariable> used = new ArrayList<LogicalVariable>();
+        VariableUtilities.getUsedVariables(op, used);
+        List<FunctionalDependency> fds1 = getOrComputeFDs(inp1, ctx);
+        List<FunctionalDependency> eFds = new ArrayList<FunctionalDependency>(fds1.size());
+        for (FunctionalDependency fd : fds1) {
+            if (fd.getTail().containsAll(used)) {
+                List<LogicalVariable> hd = new ArrayList<LogicalVariable>(fd.getHead());
+                List<LogicalVariable> tl = new ArrayList<LogicalVariable>(fd.getTail());
+                tl.addAll(op.getVariables());
+                FunctionalDependency fd2 = new FunctionalDependency(hd, tl);
+                eFds.add(fd2);
+            } else {
+                eFds.add(fd);
+            }
+        }
+        ctx.putFDList(op, eFds);
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        ILogicalOperator inp1 = op.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = getOrComputeEqClasses(inp1, ctx);
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = new ArrayList<FunctionalDependency>(getOrComputeFDs(inp1, ctx));
+        ctx.putFDList(op, fds);
+        op.getDataSource().computeFDs(op.getVariables(), fds);
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putFDList(op, functionalDependencies);
+        for (FunctionalDependency inherited : getOrComputeFDs(op0, ctx)) {
+            boolean isCoveredByDistinctByVars = true;
+            for (LogicalVariable v : inherited.getHead()) {
+                if (!op.isDistinctByVar(v)) {
+                    isCoveredByDistinctByVars = false;
+                }
+            }
+            if (isCoveredByDistinctByVars) {
+                List<LogicalVariable> newTail = new ArrayList<LogicalVariable>();
+                for (LogicalVariable v2 : inherited.getTail()) {
+                    if (op.isDistinctByVar(v2)) {
+                        newTail.add(v2);
+                    }
+                }
+                if (!newTail.isEmpty()) {
+                    List<LogicalVariable> newHead = new ArrayList<LogicalVariable>(inherited.getHead());
+                    FunctionalDependency newFd = new FunctionalDependency(newHead, newTail);
+                    functionalDependencies.add(newFd);
+                }
+            }
+        }
+        Set<LogicalVariable> gbySet = new HashSet<LogicalVariable>();
+        List<Mutable<ILogicalExpression>> expressions = op.getExpressions();
+        for (Mutable<ILogicalExpression> pRef : expressions) {
+            ILogicalExpression p = pRef.getValue();
+            if (p.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) p;
+                gbySet.add(v.getVariableReference());
+            }
+        }
+        LocalGroupingProperty lgp = new LocalGroupingProperty(gbySet);
+
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = getOrComputeEqClasses(op0, ctx);
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+
+        lgp.normalizeGroupingColumns(equivalenceClasses, functionalDependencies);
+        Set<LogicalVariable> normSet = lgp.getColumnSet();
+        List<Mutable<ILogicalExpression>> newDistinctByList = new ArrayList<Mutable<ILogicalExpression>>();
+        for (Mutable<ILogicalExpression> p2Ref : expressions) {
+            ILogicalExpression p2 = p2Ref.getValue();
+            if (p2.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression var2 = (VariableReferenceExpression) p2;
+                LogicalVariable v2 = var2.getVariableReference();
+                if (normSet.contains(v2)) {
+                    newDistinctByList.add(p2Ref);
+                }
+            } else {
+                newDistinctByList.add(p2Ref);
+            }
+        }
+        expressions.clear();
+        expressions.addAll(newDistinctByList);
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        ctx.putEquivalenceClassMap(op, new HashMap<LogicalVariable, EquivalenceClass>());
+        ctx.putFDList(op, new ArrayList<FunctionalDependency>());
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+        ctx.putFDList(op, functionalDependencies);
+
+        List<FunctionalDependency> inheritedFDs = new ArrayList<FunctionalDependency>();
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                ILogicalOperator op2 = r.getValue();
+                equivalenceClasses.putAll(getOrComputeEqClasses(op2, ctx));
+                inheritedFDs.addAll(getOrComputeFDs(op2, ctx));
+            }
+        }
+
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        inheritedFDs.addAll(getOrComputeFDs(op0, ctx));
+        Map<LogicalVariable, EquivalenceClass> inheritedEcs = getOrComputeEqClasses(op0, ctx);
+        for (FunctionalDependency inherited : inheritedFDs) {
+            boolean isCoveredByGbyOrDecorVars = true;
+            List<LogicalVariable> newHead = new ArrayList<LogicalVariable>(inherited.getHead().size());
+            for (LogicalVariable v : inherited.getHead()) {
+                LogicalVariable vnew = getNewGbyVar(op, v);
+                if (vnew == null) {
+                    vnew = getNewDecorVar(op, v);
+                    if (vnew == null) {
+                        isCoveredByGbyOrDecorVars = false;
+                    }
+                    break;
+                }
+                newHead.add(vnew);
+            }
+
+            if (isCoveredByGbyOrDecorVars) {
+                List<LogicalVariable> newTail = new ArrayList<LogicalVariable>();
+                for (LogicalVariable v2 : inherited.getTail()) {
+                    LogicalVariable v3 = getNewGbyVar(op, v2);
+                    if (v3 != null) {
+                        newTail.add(v3);
+                    }
+                }
+                if (!newTail.isEmpty()) {
+                    FunctionalDependency newFd = new FunctionalDependency(newHead, newTail);
+                    functionalDependencies.add(newFd);
+                }
+            }
+        }
+
+        List<LogicalVariable> premiseGby = new LinkedList<LogicalVariable>();
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> gByList = op.getGroupByList();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            premiseGby.add(p.first);
+        }
+
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> decorList = op.getDecorList();
+
+        LinkedList<LogicalVariable> conclDecor = new LinkedList<LogicalVariable>();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : decorList) {
+            conclDecor.add(GroupByOperator.getDecorVariable(p));
+        }
+        if (!conclDecor.isEmpty()) {
+            functionalDependencies.add(new FunctionalDependency(premiseGby, conclDecor));
+        }
+
+        Set<LogicalVariable> gbySet = new HashSet<LogicalVariable>();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) expr;
+                gbySet.add(v.getVariableReference());
+            }
+        }
+        LocalGroupingProperty lgp = new LocalGroupingProperty(gbySet);
+        lgp.normalizeGroupingColumns(inheritedEcs, inheritedFDs);
+        Set<LogicalVariable> normSet = lgp.getColumnSet();
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> newGbyList = new ArrayList<Pair<LogicalVariable, Mutable<ILogicalExpression>>>();
+        boolean changed = false;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gByList) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression varRef = (VariableReferenceExpression) expr;
+                LogicalVariable v2 = varRef.getVariableReference();
+                EquivalenceClass ec2 = inheritedEcs.get(v2);
+                LogicalVariable v3;
+                if (ec2 != null && !ec2.representativeIsConst()) {
+                    v3 = ec2.getVariableRepresentative();
+                } else {
+                    v3 = v2;
+                }
+                if (normSet.contains(v3)) {
+                    newGbyList.add(p);
+                } else {
+                    changed = true;
+                    decorList.add(p);
+                }
+            } else {
+                newGbyList.add(p);
+            }
+        }
+        if (changed) {
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine(">>>> Group-by list changed from "
+                    + GroupByOperator.veListToString(gByList) + " to " + GroupByOperator.veListToString(newGbyList)
+                    + ".\n");
+        }
+        gByList.clear();
+        gByList.addAll(newGbyList);
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+        ctx.putFDList(op, functionalDependencies);
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        ILogicalOperator op1 = op.getInputs().get(1).getValue();
+        functionalDependencies.addAll(getOrComputeFDs(op0, ctx));
+        functionalDependencies.addAll(getOrComputeFDs(op1, ctx));
+        equivalenceClasses.putAll(getOrComputeEqClasses(op0, ctx));
+        equivalenceClasses.putAll(getOrComputeEqClasses(op1, ctx));
+        ILogicalExpression expr = op.getCondition().getValue();
+        expr.getConstraintsAndEquivClasses(functionalDependencies, equivalenceClasses);
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+        ctx.putFDList(op, functionalDependencies);
+        ILogicalOperator opLeft = op.getInputs().get(0).getValue();
+        ILogicalOperator opRight = op.getInputs().get(1).getValue();
+        functionalDependencies.addAll(getOrComputeFDs(opLeft, ctx));
+        functionalDependencies.addAll(getOrComputeFDs(opRight, ctx));
+        equivalenceClasses.putAll(getOrComputeEqClasses(opLeft, ctx));
+        equivalenceClasses.putAll(getOrComputeEqClasses(opRight, ctx));
+
+        Collection<LogicalVariable> leftSideVars;
+        if (opLeft.getSchema() == null) {
+            leftSideVars = new LinkedList<LogicalVariable>();
+            VariableUtilities.getLiveVariables(opLeft, leftSideVars);
+            // actually, not all produced vars. are visible (due to projection)
+            // so using cached schema is better and faster
+        } else {
+            leftSideVars = opLeft.getSchema();
+        }
+        ILogicalExpression expr = op.getCondition().getValue();
+        expr.getConstraintsForOuterJoin(functionalDependencies, leftSideVars);
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        AbstractLogicalOperator op1 = (AbstractLogicalOperator) op.getDataSourceReference().getValue();
+        ILogicalOperator inp1 = op1.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = getOrComputeEqClasses(inp1, ctx);
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = new ArrayList<FunctionalDependency>(getOrComputeFDs(inp1, ctx));
+        if (op1.getOperatorTag() == LogicalOperatorTag.GROUP) {
+            GroupByOperator gby = (GroupByOperator) op1;
+            LinkedList<LogicalVariable> tail = new LinkedList<LogicalVariable>();
+            for (LogicalVariable v : gby.getGbyVarList()) {
+                tail.add(v);
+                // all values for gby vars. are the same
+            }
+            FunctionalDependency gbyfd = new FunctionalDependency(new LinkedList<LogicalVariable>(), tail);
+            fds.add(gbyfd);
+        }
+        ctx.putFDList(op, fds);
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        throw new NotImplementedException();
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClassesForUsedVars(op, ctx, op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClassesForUsedVars(op, ctx, op.getInputVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+        ctx.putFDList(op, functionalDependencies);
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        functionalDependencies.addAll(getOrComputeFDs(op0, ctx));
+        equivalenceClasses.putAll(getOrComputeEqClasses(op0, ctx));
+        ILogicalExpression expr = op.getCondition().getValue();
+        expr.getConstraintsAndEquivClasses(functionalDependencies, equivalenceClasses);
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> equivalenceClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        List<FunctionalDependency> functionalDependencies = new ArrayList<FunctionalDependency>();
+        ctx.putEquivalenceClassMap(op, equivalenceClasses);
+        ctx.putFDList(op, functionalDependencies);
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                ILogicalOperator op2 = r.getValue();
+                equivalenceClasses.putAll(getOrComputeEqClasses(op2, ctx));
+                functionalDependencies.addAll(getOrComputeFDs(op2, ctx));
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        fdsEqClassesForAbstractUnnestOperator(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        fdsEqClassesForAbstractUnnestOperator(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        // propagateFDsAndEquivClasses(op, ctx);
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        // propagateFDsAndEquivClasses(op, ctx);
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        setEmptyFDsEqClasses(op, ctx);
+        return null;
+    }
+
+    private void propagateFDsAndEquivClasses(ILogicalOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        ILogicalOperator inp1 = op.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = getOrComputeEqClasses(inp1, ctx);
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = getOrComputeFDs(inp1, ctx);
+        ctx.putFDList(op, fds);
+    }
+
+    private Map<LogicalVariable, EquivalenceClass> getOrComputeEqClasses(ILogicalOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        Map<LogicalVariable, EquivalenceClass> eqClasses = ctx.getEquivalenceClassMap(op);
+        if (eqClasses == null) {
+            op.accept(this, ctx);
+            eqClasses = ctx.getEquivalenceClassMap(op);
+        }
+        return eqClasses;
+    }
+
+    private List<FunctionalDependency> getOrComputeFDs(ILogicalOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        List<FunctionalDependency> fds = ctx.getFDList(op);
+        if (fds == null) {
+            op.accept(this, ctx);
+            fds = ctx.getFDList(op);
+        }
+        return fds;
+    }
+
+    private void propagateFDsAndEquivClassesForUsedVars(ILogicalOperator op, IOptimizationContext ctx,
+            List<LogicalVariable> usedVariables) throws AlgebricksException {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = new ArrayList<FunctionalDependency>();
+        ctx.putFDList(op, fds);
+
+        Map<LogicalVariable, EquivalenceClass> chldClasses = getOrComputeEqClasses(op2, ctx);
+        for (LogicalVariable v : usedVariables) {
+            EquivalenceClass ec = eqClasses.get(v);
+            if (ec == null) {
+                EquivalenceClass oc = chldClasses.get(v);
+                if (oc == null) {
+                    continue;
+                }
+                List<LogicalVariable> m = new LinkedList<LogicalVariable>();
+                for (LogicalVariable v2 : oc.getMembers()) {
+                    if (usedVariables.contains(v2)) {
+                        m.add(v2);
+                    }
+                }
+                EquivalenceClass nc;
+                if (oc.representativeIsConst()) {
+                    nc = new EquivalenceClass(m, oc.getConstRepresentative());
+                } else if (m.contains(oc.getVariableRepresentative())) {
+                    nc = new EquivalenceClass(m, oc.getVariableRepresentative());
+                } else {
+                    nc = new EquivalenceClass(m, v);
+                }
+                for (LogicalVariable v3 : m) {
+                    eqClasses.put(v3, nc);
+                }
+            }
+        }
+
+        List<FunctionalDependency> chldFds = getOrComputeFDs(op2, ctx);
+        for (FunctionalDependency fd : chldFds) {
+            if (!usedVariables.containsAll(fd.getHead())) {
+                continue;
+            }
+            List<LogicalVariable> tl = new LinkedList<LogicalVariable>();
+            for (LogicalVariable v : fd.getTail()) {
+                if (usedVariables.contains(v)) {
+                    tl.add(v);
+                }
+            }
+            if (!tl.isEmpty()) {
+                FunctionalDependency newFd = new FunctionalDependency(fd.getHead(), tl);
+                fds.add(newFd);
+            }
+        }
+    }
+
+    private void fdsEqClassesForAbstractUnnestOperator(AbstractUnnestOperator op, IOptimizationContext ctx)
+            throws AlgebricksException {
+        ILogicalOperator inp1 = op.getInputs().get(0).getValue();
+        Map<LogicalVariable, EquivalenceClass> eqClasses = getOrComputeEqClasses(inp1, ctx);
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = getOrComputeFDs(inp1, ctx);
+        ctx.putFDList(op, fds);
+
+        ILogicalExpression expr = op.getExpressionRef().getValue();
+        if (expr.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
+            AbstractFunctionCallExpression afe = (AbstractFunctionCallExpression) expr;
+            if (afe.getKind() == FunctionKind.UNNEST && ((UnnestingFunctionCallExpression) afe).returnsUniqueValues()) {
+                List<LogicalVariable> vars = new ArrayList<LogicalVariable>();
+                VariableUtilities.getLiveVariables(op, vars);
+                ArrayList<LogicalVariable> h = new ArrayList<LogicalVariable>();
+                h.addAll(op.getVariables());
+                FunctionalDependency fd = new FunctionalDependency(h, vars);
+                fds.add(fd);
+            }
+        }
+    }
+
+    public static void setEmptyFDsEqClasses(ILogicalOperator op, IOptimizationContext ctx) {
+        Map<LogicalVariable, EquivalenceClass> eqClasses = new HashMap<LogicalVariable, EquivalenceClass>();
+        ctx.putEquivalenceClassMap(op, eqClasses);
+        List<FunctionalDependency> fds = new ArrayList<FunctionalDependency>();
+        ctx.putFDList(op, fds);
+    }
+
+    private LogicalVariable getNewGbyVar(GroupByOperator g, LogicalVariable v) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : g.getGroupByList()) {
+            ILogicalExpression e = p.second.getValue();
+            if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                LogicalVariable v2 = ((VariableReferenceExpression) e).getVariableReference();
+                if (v2 == v) {
+                    return p.first;
+                }
+            }
+        }
+        return null;
+    }
+
+    private LogicalVariable getNewDecorVar(GroupByOperator g, LogicalVariable v) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : g.getDecorList()) {
+            ILogicalExpression e = p.second.getValue();
+            if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                LogicalVariable v2 = ((VariableReferenceExpression) e).getVariableReference();
+                if (v2 == v) {
+                    return (p.first != null) ? p.first : v2;
+                }
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, IOptimizationContext ctx) throws AlgebricksException {
+        propagateFDsAndEquivClasses(op, ctx);
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
new file mode 100644
index 0000000..31061db
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
@@ -0,0 +1,825 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractLogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.plan.ALogicalPlanImpl;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class IsomorphismOperatorVisitor implements ILogicalOperatorVisitor<Boolean, ILogicalOperator> {
+
+    private Map<LogicalVariable, LogicalVariable> variableMapping = new HashMap<LogicalVariable, LogicalVariable>();
+
+    public IsomorphismOperatorVisitor() {
+    }
+
+    @Override
+    public Boolean visitAggregateOperator(AggregateOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.AGGREGATE)
+            return Boolean.FALSE;
+        AggregateOperator aggOpArg = (AggregateOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(
+                getPairList(op.getVariables(), op.getExpressions()),
+                getPairList(aggOpArg.getVariables(), aggOpArg.getExpressions()));
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitRunningAggregateOperator(RunningAggregateOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.RUNNINGAGGREGATE)
+            return Boolean.FALSE;
+        RunningAggregateOperator aggOpArg = (RunningAggregateOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(
+                getPairList(op.getVariables(), op.getExpressions()),
+                getPairList(aggOpArg.getVariables(), aggOpArg.getExpressions()));
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) copyAndSubstituteVar(op, arg);
+        if (aop.getOperatorTag() != LogicalOperatorTag.EMPTYTUPLESOURCE)
+            return Boolean.FALSE;
+        return Boolean.TRUE;
+    }
+
+    @Override
+    public Boolean visitExtensionOperator(ExtensionOperator op, ILogicalOperator arg) throws AlgebricksException {
+        ExtensionOperator aop = (ExtensionOperator) copyAndSubstituteVar(op, arg);
+        if (aop.getOperatorTag() != LogicalOperatorTag.EXTENSION_OPERATOR)
+            return Boolean.FALSE;
+        return Boolean.TRUE;
+    }
+
+    @Override
+    public Boolean visitGroupByOperator(GroupByOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        // require the same physical operator, otherwise delivers different data
+        // properties
+        if (aop.getOperatorTag() != LogicalOperatorTag.GROUP
+                || aop.getPhysicalOperator().getOperatorTag() != op.getPhysicalOperator().getOperatorTag())
+            return Boolean.FALSE;
+
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> keyLists = op.getGroupByList();
+        GroupByOperator gbyOpArg = (GroupByOperator) copyAndSubstituteVar(op, arg);
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> keyListsArg = gbyOpArg.getGroupByList();
+
+        List<Pair<LogicalVariable, ILogicalExpression>> listLeft = new ArrayList<Pair<LogicalVariable, ILogicalExpression>>();
+        List<Pair<LogicalVariable, ILogicalExpression>> listRight = new ArrayList<Pair<LogicalVariable, ILogicalExpression>>();
+
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> pair : keyLists)
+            listLeft.add(new Pair<LogicalVariable, ILogicalExpression>(pair.first, pair.second.getValue()));
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> pair : keyListsArg)
+            listRight.add(new Pair<LogicalVariable, ILogicalExpression>(pair.first, pair.second.getValue()));
+
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(listLeft, listRight);
+
+        if (!isomorphic)
+            return Boolean.FALSE;
+        int sizeOp = op.getNestedPlans().size();
+        int sizeArg = gbyOpArg.getNestedPlans().size();
+        if (sizeOp != sizeArg)
+            return Boolean.FALSE;
+
+        GroupByOperator argOp = (GroupByOperator) arg;
+        List<ILogicalPlan> plans = op.getNestedPlans();
+        List<ILogicalPlan> plansArg = argOp.getNestedPlans();
+        for (int i = 0; i < plans.size(); i++) {
+            List<Mutable<ILogicalOperator>> roots = plans.get(i).getRoots();
+            List<Mutable<ILogicalOperator>> rootsArg = plansArg.get(i).getRoots();
+            if (roots.size() != rootsArg.size())
+                return Boolean.FALSE;
+            for (int j = 0; j < roots.size(); j++) {
+                ILogicalOperator topOp1 = roots.get(j).getValue();
+                ILogicalOperator topOp2 = rootsArg.get(j).getValue();
+                isomorphic = this.checkBottomUp(topOp1, topOp2);
+                if (!isomorphic)
+                    return Boolean.FALSE;
+            }
+        }
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitLimitOperator(LimitOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.LIMIT)
+            return Boolean.FALSE;
+        LimitOperator limitOpArg = (LimitOperator) copyAndSubstituteVar(op, arg);
+        if (op.getOffset() != limitOpArg.getOffset())
+            return Boolean.FALSE;
+        boolean isomorphic = op.getMaxObjects().getValue().equals(limitOpArg.getMaxObjects().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitDieOperator(DieOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.DIE)
+            return Boolean.FALSE;
+        DieOperator dieOpArg = (DieOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = op.getAfterObjects().getValue().equals(dieOpArg.getAfterObjects().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitInnerJoinOperator(InnerJoinOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.INNERJOIN)
+            return Boolean.FALSE;
+        InnerJoinOperator joinOpArg = (InnerJoinOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = op.getCondition().getValue().equals(joinOpArg.getCondition().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitLeftOuterJoinOperator(LeftOuterJoinOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.LEFTOUTERJOIN)
+            return Boolean.FALSE;
+        LeftOuterJoinOperator joinOpArg = (LeftOuterJoinOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = op.getCondition().getValue().equals(joinOpArg.getCondition().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitNestedTupleSourceOperator(NestedTupleSourceOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.NESTEDTUPLESOURCE)
+            return Boolean.FALSE;
+        return Boolean.TRUE;
+    }
+
+    @Override
+    public Boolean visitOrderOperator(OrderOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.ORDER)
+            return Boolean.FALSE;
+        OrderOperator orderOpArg = (OrderOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = compareIOrderAndExpressions(op.getOrderExpressions(), orderOpArg.getOrderExpressions());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitAssignOperator(AssignOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.ASSIGN)
+            return Boolean.FALSE;
+        AssignOperator assignOpArg = (AssignOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(
+                getPairList(op.getVariables(), op.getExpressions()),
+                getPairList(assignOpArg.getVariables(), assignOpArg.getExpressions()));
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitSelectOperator(SelectOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.SELECT)
+            return Boolean.FALSE;
+        SelectOperator selectOpArg = (SelectOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = op.getCondition().getValue().equals(selectOpArg.getCondition().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitProjectOperator(ProjectOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.PROJECT)
+            return Boolean.FALSE;
+        ProjectOperator projectOpArg = (ProjectOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getVariables(), projectOpArg.getVariables());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitPartitioningSplitOperator(PartitioningSplitOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.PARTITIONINGSPLIT)
+            return Boolean.FALSE;
+        PartitioningSplitOperator partitionOpArg = (PartitioningSplitOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = compareExpressions(op.getExpressions(), partitionOpArg.getExpressions());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitReplicateOperator(ReplicateOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.REPLICATE)
+            return Boolean.FALSE;
+        return Boolean.TRUE;
+    }
+
+    @Override
+    public Boolean visitScriptOperator(ScriptOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.SCRIPT)
+            return Boolean.FALSE;
+        ScriptOperator scriptOpArg = (ScriptOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = op.getScriptDescription().equals(scriptOpArg.getScriptDescription());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitSubplanOperator(SubplanOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.SUBPLAN)
+            return Boolean.FALSE;
+        SubplanOperator subplanOpArg = (SubplanOperator) copyAndSubstituteVar(op, arg);
+        List<ILogicalPlan> plans = op.getNestedPlans();
+        List<ILogicalPlan> plansArg = subplanOpArg.getNestedPlans();
+        for (int i = 0; i < plans.size(); i++) {
+            List<Mutable<ILogicalOperator>> roots = plans.get(i).getRoots();
+            List<Mutable<ILogicalOperator>> rootsArg = plansArg.get(i).getRoots();
+            if (roots.size() == rootsArg.size())
+                return Boolean.FALSE;
+            for (int j = 0; j < roots.size(); j++) {
+                ILogicalOperator topOp1 = roots.get(j).getValue();
+                ILogicalOperator topOp2 = rootsArg.get(j).getValue();
+                boolean isomorphic = this.checkBottomUp(topOp1, topOp2);
+                if (!isomorphic)
+                    return Boolean.FALSE;
+            }
+        }
+        return Boolean.TRUE;
+    }
+
+    @Override
+    public Boolean visitUnionOperator(UnionAllOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.UNIONALL)
+            return Boolean.FALSE;
+        UnionAllOperator unionOpArg = (UnionAllOperator) copyAndSubstituteVar(op, arg);
+        List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> mapping = op.getVariableMappings();
+        List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> mappingArg = unionOpArg.getVariableMappings();
+        if (mapping.size() != mappingArg.size())
+            return Boolean.FALSE;
+        return VariableUtilities.varListEqualUnordered(mapping, mappingArg);
+    }
+
+    @Override
+    public Boolean visitUnnestOperator(UnnestOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.UNNEST)
+            return Boolean.FALSE;
+        UnnestOperator unnestOpArg = (UnnestOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getVariables(), unnestOpArg.getVariables())
+                && variableEqual(op.getPositionalVariable(), unnestOpArg.getPositionalVariable());
+        if (!isomorphic)
+            return Boolean.FALSE;
+        isomorphic = op.getExpressionRef().getValue().equals(unnestOpArg.getExpressionRef().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitUnnestMapOperator(UnnestMapOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.UNNEST_MAP)
+            return Boolean.FALSE;
+        UnnestOperator unnestOpArg = (UnnestOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getVariables(), unnestOpArg.getVariables());
+        if (!isomorphic)
+            return Boolean.FALSE;
+        isomorphic = op.getExpressionRef().getValue().equals(unnestOpArg.getExpressionRef().getValue());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitDataScanOperator(DataSourceScanOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.DATASOURCESCAN)
+            return Boolean.FALSE;
+        DataSourceScanOperator argScan = (DataSourceScanOperator) arg;
+        if (!argScan.getDataSource().toString().equals(op.getDataSource().toString()))
+            return Boolean.FALSE;
+        DataSourceScanOperator scanOpArg = (DataSourceScanOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getVariables(), scanOpArg.getVariables())
+                && op.getDataSource().toString().equals(scanOpArg.getDataSource().toString());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitDistinctOperator(DistinctOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.DISTINCT)
+            return Boolean.FALSE;
+        DistinctOperator distinctOpArg = (DistinctOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = compareExpressions(op.getExpressions(), distinctOpArg.getExpressions());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitExchangeOperator(ExchangeOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.EXCHANGE)
+            return Boolean.FALSE;
+        // require the same partition property
+        if (!(op.getPhysicalOperator().getOperatorTag() == aop.getPhysicalOperator().getOperatorTag()))
+            return Boolean.FALSE;
+        variableMapping.clear();
+        IsomorphismUtilities.mapVariablesTopDown(op, arg, variableMapping);
+        IPhysicalPropertiesVector properties = op.getPhysicalOperator().getDeliveredProperties();
+        IPhysicalPropertiesVector propertiesArg = aop.getPhysicalOperator().getDeliveredProperties();
+        if (properties == null && propertiesArg == null)
+            return Boolean.TRUE;
+        if (properties == null || propertiesArg == null)
+            return Boolean.FALSE;
+        IPartitioningProperty partProp = properties.getPartitioningProperty();
+        IPartitioningProperty partPropArg = propertiesArg.getPartitioningProperty();
+        if (!partProp.getPartitioningType().equals(partPropArg.getPartitioningType()))
+            return Boolean.FALSE;
+        List<LogicalVariable> columns = new ArrayList<LogicalVariable>();
+        partProp.getColumns(columns);
+        List<LogicalVariable> columnsArg = new ArrayList<LogicalVariable>();
+        partPropArg.getColumns(columnsArg);
+        if (columns.size() != columnsArg.size())
+            return Boolean.FALSE;
+        if (columns.size() == 0)
+            return Boolean.TRUE;
+        for (int i = 0; i < columnsArg.size(); i++) {
+            LogicalVariable rightVar = columnsArg.get(i);
+            LogicalVariable leftVar = variableMapping.get(rightVar);
+            if (leftVar != null)
+                columnsArg.set(i, leftVar);
+        }
+        return VariableUtilities.varListEqualUnordered(columns, columnsArg);
+    }
+
+    @Override
+    public Boolean visitWriteOperator(WriteOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.WRITE)
+            return Boolean.FALSE;
+        WriteOperator writeOpArg = (WriteOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getSchema(), writeOpArg.getSchema());
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitWriteResultOperator(WriteResultOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.WRITE_RESULT)
+            return Boolean.FALSE;
+        WriteResultOperator writeOpArg = (WriteResultOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getSchema(), writeOpArg.getSchema());
+        if (!op.getDataSource().equals(writeOpArg.getDataSource()))
+            isomorphic = false;
+        if (!op.getPayloadExpression().equals(writeOpArg.getPayloadExpression()))
+            isomorphic = false;
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitInsertDeleteOperator(InsertDeleteOperator op, ILogicalOperator arg) throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.INSERT_DELETE)
+            return Boolean.FALSE;
+        InsertDeleteOperator insertOpArg = (InsertDeleteOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getSchema(), insertOpArg.getSchema());
+        if (!op.getDataSource().equals(insertOpArg.getDataSource()))
+            isomorphic = false;
+        if (!op.getPayloadExpression().equals(insertOpArg.getPayloadExpression()))
+            isomorphic = false;
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.INDEX_INSERT_DELETE)
+            return Boolean.FALSE;
+        IndexInsertDeleteOperator insertOpArg = (IndexInsertDeleteOperator) copyAndSubstituteVar(op, arg);
+        boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getSchema(), insertOpArg.getSchema());
+        if (!op.getDataSourceIndex().equals(insertOpArg.getDataSourceIndex()))
+            isomorphic = false;
+        return isomorphic;
+    }
+
+    @Override
+    public Boolean visitSinkOperator(SinkOperator op, ILogicalOperator arg) throws AlgebricksException {
+        return true;
+    }
+
+    private Boolean compareExpressions(List<Mutable<ILogicalExpression>> opExprs,
+            List<Mutable<ILogicalExpression>> argExprs) {
+        if (opExprs.size() != argExprs.size())
+            return Boolean.FALSE;
+        for (int i = 0; i < opExprs.size(); i++) {
+            boolean isomorphic = opExprs.get(i).getValue().equals(argExprs.get(i).getValue());
+            if (!isomorphic)
+                return Boolean.FALSE;
+        }
+        return Boolean.TRUE;
+    }
+
+    private Boolean compareIOrderAndExpressions(List<Pair<IOrder, Mutable<ILogicalExpression>>> opOrderExprs,
+            List<Pair<IOrder, Mutable<ILogicalExpression>>> argOrderExprs) {
+        if (opOrderExprs.size() != argOrderExprs.size())
+            return Boolean.FALSE;
+        for (int i = 0; i < opOrderExprs.size(); i++) {
+            boolean isomorphic = opOrderExprs.get(i).first.equals(argOrderExprs.get(i).first);
+            if (!isomorphic)
+                return Boolean.FALSE;
+            isomorphic = opOrderExprs.get(i).second.getValue().equals(argOrderExprs.get(i).second.getValue());
+            if (!isomorphic)
+                return Boolean.FALSE;
+        }
+        return Boolean.TRUE;
+    }
+
+    private Boolean checkBottomUp(ILogicalOperator op1, ILogicalOperator op2) throws AlgebricksException {
+        List<Mutable<ILogicalOperator>> inputs1 = op1.getInputs();
+        List<Mutable<ILogicalOperator>> inputs2 = op2.getInputs();
+        if (inputs1.size() != inputs2.size())
+            return Boolean.FALSE;
+        for (int i = 0; i < inputs1.size(); i++) {
+            ILogicalOperator input1 = inputs1.get(i).getValue();
+            ILogicalOperator input2 = inputs2.get(i).getValue();
+            boolean isomorphic = checkBottomUp(input1, input2);
+            if (!isomorphic)
+                return Boolean.FALSE;
+        }
+        return IsomorphismUtilities.isOperatorIsomorphic(op1, op2);
+    }
+
+    private ILogicalOperator copyAndSubstituteVar(ILogicalOperator op, ILogicalOperator argOp)
+            throws AlgebricksException {
+        ILogicalOperator newOp = IsomorphismOperatorVisitor.deepCopy(argOp);
+        variableMapping.clear();
+        IsomorphismUtilities.mapVariablesTopDown(op, argOp, variableMapping);
+
+        List<LogicalVariable> liveVars = new ArrayList<LogicalVariable>();
+        if (argOp.getInputs().size() > 0)
+            for (int i = 0; i < argOp.getInputs().size(); i++)
+                VariableUtilities.getLiveVariables(argOp.getInputs().get(i).getValue(), liveVars);
+        List<LogicalVariable> producedVars = new ArrayList<LogicalVariable>();
+        VariableUtilities.getProducedVariables(argOp, producedVars);
+        List<LogicalVariable> producedVarsNew = new ArrayList<LogicalVariable>();
+        VariableUtilities.getProducedVariables(op, producedVarsNew);
+
+        if (producedVars.size() != producedVarsNew.size())
+            return newOp;
+        for (Entry<LogicalVariable, LogicalVariable> map : variableMapping.entrySet()) {
+            if (liveVars.contains(map.getKey())) {
+                VariableUtilities.substituteVariables(newOp, map.getKey(), map.getValue(), null);
+            }
+        }
+        for (int i = 0; i < producedVars.size(); i++)
+            VariableUtilities.substituteVariables(newOp, producedVars.get(i), producedVarsNew.get(i), null);
+        return newOp;
+    }
+
+    public List<Pair<LogicalVariable, ILogicalExpression>> getPairList(List<LogicalVariable> vars,
+            List<Mutable<ILogicalExpression>> exprs) throws AlgebricksException {
+        List<Pair<LogicalVariable, ILogicalExpression>> list = new ArrayList<Pair<LogicalVariable, ILogicalExpression>>();
+        if (vars.size() != exprs.size())
+            throw new AlgebricksException("variable list size does not equal to expression list size ");
+        for (int i = 0; i < vars.size(); i++) {
+            list.add(new Pair<LogicalVariable, ILogicalExpression>(vars.get(i), exprs.get(i).getValue()));
+        }
+        return list;
+    }
+
+    private static ILogicalOperator deepCopy(ILogicalOperator op) throws AlgebricksException {
+        OperatorDeepCopyVisitor visitor = new OperatorDeepCopyVisitor();
+        return op.accept(visitor, null);
+    }
+
+    private static ILogicalPlan deepCopy(ILogicalPlan plan) throws AlgebricksException {
+        List<Mutable<ILogicalOperator>> roots = plan.getRoots();
+        List<Mutable<ILogicalOperator>> newRoots = new ArrayList<Mutable<ILogicalOperator>>();
+        for (Mutable<ILogicalOperator> opRef : roots)
+            newRoots.add(new MutableObject<ILogicalOperator>(bottomUpCopyOperators(opRef.getValue())));
+        return new ALogicalPlanImpl(newRoots);
+    }
+
+    private static ILogicalOperator bottomUpCopyOperators(ILogicalOperator op) throws AlgebricksException {
+        ILogicalOperator newOp = deepCopy(op);
+        newOp.getInputs().clear();
+        for (Mutable<ILogicalOperator> child : op.getInputs())
+            newOp.getInputs().add(new MutableObject<ILogicalOperator>(bottomUpCopyOperators(child.getValue())));
+        return newOp;
+    }
+
+    private static boolean variableEqual(LogicalVariable var, LogicalVariable varArg) {
+        if (var == null && varArg == null)
+            return true;
+        if (var.equals(varArg))
+            return true;
+        else
+            return false;
+    }
+
+    private static class OperatorDeepCopyVisitor implements ILogicalOperatorVisitor<ILogicalOperator, Void> {
+
+        @Override
+        public ILogicalOperator visitAggregateOperator(AggregateOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newList = new ArrayList<LogicalVariable>();
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            newList.addAll(op.getVariables());
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new AggregateOperator(newList, newExpressions);
+        }
+
+        @Override
+        public ILogicalOperator visitRunningAggregateOperator(RunningAggregateOperator op, Void arg)
+                throws AlgebricksException {
+            ArrayList<LogicalVariable> newList = new ArrayList<LogicalVariable>();
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            newList.addAll(op.getVariables());
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new RunningAggregateOperator(newList, newExpressions);
+        }
+
+        @Override
+        public ILogicalOperator visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Void arg)
+                throws AlgebricksException {
+            return new EmptyTupleSourceOperator();
+        }
+
+        @Override
+        public ILogicalOperator visitGroupByOperator(GroupByOperator op, Void arg) throws AlgebricksException {
+            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> groupByList = new ArrayList<Pair<LogicalVariable, Mutable<ILogicalExpression>>>();
+            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> decoList = new ArrayList<Pair<LogicalVariable, Mutable<ILogicalExpression>>>();
+            ArrayList<ILogicalPlan> newSubplans = new ArrayList<ILogicalPlan>();
+            for (Pair<LogicalVariable, Mutable<ILogicalExpression>> pair : op.getGroupByList())
+                groupByList.add(new Pair<LogicalVariable, Mutable<ILogicalExpression>>(pair.first,
+                        deepCopyExpressionRef(pair.second)));
+            for (Pair<LogicalVariable, Mutable<ILogicalExpression>> pair : op.getDecorList())
+                decoList.add(new Pair<LogicalVariable, Mutable<ILogicalExpression>>(pair.first,
+                        deepCopyExpressionRef(pair.second)));
+            for (ILogicalPlan plan : op.getNestedPlans()) {
+                newSubplans.add(IsomorphismOperatorVisitor.deepCopy(plan));
+            }
+            return new GroupByOperator(groupByList, decoList, newSubplans);
+        }
+
+        @Override
+        public ILogicalOperator visitLimitOperator(LimitOperator op, Void arg) throws AlgebricksException {
+            return new LimitOperator(deepCopyExpressionRef(op.getMaxObjects()).getValue(), deepCopyExpressionRef(
+                    op.getOffset()).getValue(), op.isTopmostLimitOp());
+        }
+
+        @Override
+        public ILogicalOperator visitDieOperator(DieOperator op, Void arg) throws AlgebricksException {
+            return new DieOperator(deepCopyExpressionRef(op.getAfterObjects()).getValue());
+        }
+
+        @Override
+        public ILogicalOperator visitInnerJoinOperator(InnerJoinOperator op, Void arg) throws AlgebricksException {
+            return new InnerJoinOperator(deepCopyExpressionRef(op.getCondition()), op.getInputs().get(0), op
+                    .getInputs().get(1));
+        }
+
+        @Override
+        public ILogicalOperator visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Void arg)
+                throws AlgebricksException {
+            return new LeftOuterJoinOperator(deepCopyExpressionRef(op.getCondition()), op.getInputs().get(0), op
+                    .getInputs().get(1));
+        }
+
+        @Override
+        public ILogicalOperator visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Void arg)
+                throws AlgebricksException {
+            return new NestedTupleSourceOperator(null);
+        }
+
+        @Override
+        public ILogicalOperator visitOrderOperator(OrderOperator op, Void arg) throws AlgebricksException {
+            return new OrderOperator(this.deepCopyOrderAndExpression(op.getOrderExpressions()));
+        }
+
+        @Override
+        public ILogicalOperator visitAssignOperator(AssignOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newList = new ArrayList<LogicalVariable>();
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            newList.addAll(op.getVariables());
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new AssignOperator(newList, newExpressions);
+        }
+
+        @Override
+        public ILogicalOperator visitSelectOperator(SelectOperator op, Void arg) throws AlgebricksException {
+            return new SelectOperator(deepCopyExpressionRef(op.getCondition()));
+        }
+
+        @Override
+        public ILogicalOperator visitProjectOperator(ProjectOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newList = new ArrayList<LogicalVariable>();
+            newList.addAll(op.getVariables());
+            return new ProjectOperator(newList);
+        }
+
+        @Override
+        public ILogicalOperator visitPartitioningSplitOperator(PartitioningSplitOperator op, Void arg)
+                throws AlgebricksException {
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new PartitioningSplitOperator(newExpressions, op.getDefaultBranchIndex());
+        }
+
+        @Override
+        public ILogicalOperator visitReplicateOperator(ReplicateOperator op, Void arg) throws AlgebricksException {
+            return new ReplicateOperator(op.getOutputArity());
+        }
+
+        @Override
+        public ILogicalOperator visitScriptOperator(ScriptOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newInputList = new ArrayList<LogicalVariable>();
+            ArrayList<LogicalVariable> newOutputList = new ArrayList<LogicalVariable>();
+            newInputList.addAll(op.getInputVariables());
+            newOutputList.addAll(op.getOutputVariables());
+            return new ScriptOperator(op.getScriptDescription(), newInputList, newOutputList);
+        }
+
+        @Override
+        public ILogicalOperator visitSubplanOperator(SubplanOperator op, Void arg) throws AlgebricksException {
+            ArrayList<ILogicalPlan> newSubplans = new ArrayList<ILogicalPlan>();
+            for (ILogicalPlan plan : op.getNestedPlans()) {
+                newSubplans.add(IsomorphismOperatorVisitor.deepCopy(plan));
+            }
+            return new SubplanOperator(newSubplans);
+        }
+
+        @Override
+        public ILogicalOperator visitUnionOperator(UnionAllOperator op, Void arg) throws AlgebricksException {
+            List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> newVarMap = new ArrayList<Triple<LogicalVariable, LogicalVariable, LogicalVariable>>();
+            List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> varMap = op.getVariableMappings();
+            for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> triple : varMap)
+                newVarMap.add(new Triple<LogicalVariable, LogicalVariable, LogicalVariable>(triple.first,
+                        triple.second, triple.third));
+            return new UnionAllOperator(newVarMap);
+        }
+
+        @Override
+        public ILogicalOperator visitUnnestOperator(UnnestOperator op, Void arg) throws AlgebricksException {
+            return new UnnestOperator(op.getVariable(), deepCopyExpressionRef(op.getExpressionRef()),
+                    op.getPositionalVariable(), op.getPositionalVariableType());
+        }
+
+        @Override
+        public ILogicalOperator visitUnnestMapOperator(UnnestMapOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newInputList = new ArrayList<LogicalVariable>();
+            newInputList.addAll(op.getVariables());
+            return new UnnestMapOperator(newInputList, deepCopyExpressionRef(op.getExpressionRef()),
+                    new ArrayList<Object>(op.getVariableTypes()), op.propagatesInput());
+        }
+
+        @Override
+        public ILogicalOperator visitDataScanOperator(DataSourceScanOperator op, Void arg) throws AlgebricksException {
+            ArrayList<LogicalVariable> newInputList = new ArrayList<LogicalVariable>();
+            newInputList.addAll(op.getVariables());
+            return new DataSourceScanOperator(newInputList, op.getDataSource());
+        }
+
+        @Override
+        public ILogicalOperator visitDistinctOperator(DistinctOperator op, Void arg) throws AlgebricksException {
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new DistinctOperator(newExpressions);
+        }
+
+        @Override
+        public ILogicalOperator visitExchangeOperator(ExchangeOperator op, Void arg) throws AlgebricksException {
+            return new ExchangeOperator();
+        }
+
+        @Override
+        public ILogicalOperator visitWriteOperator(WriteOperator op, Void arg) throws AlgebricksException {
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new WriteOperator(newExpressions, op.getDataSink());
+        }
+
+        @Override
+        public ILogicalOperator visitWriteResultOperator(WriteResultOperator op, Void arg) throws AlgebricksException {
+            ArrayList<Mutable<ILogicalExpression>> newKeyExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newKeyExpressions, op.getKeyExpressions());
+            return new WriteResultOperator(op.getDataSource(), deepCopyExpressionRef(op.getPayloadExpression()),
+                    newKeyExpressions);
+        }
+
+        @Override
+        public ILogicalOperator visitInsertDeleteOperator(InsertDeleteOperator op, Void arg) throws AlgebricksException {
+            List<Mutable<ILogicalExpression>> newKeyExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newKeyExpressions, op.getPrimaryKeyExpressions());
+            return new InsertDeleteOperator(op.getDataSource(), deepCopyExpressionRef(op.getPayloadExpression()),
+                    newKeyExpressions, op.getOperation());
+        }
+
+        @Override
+        public ILogicalOperator visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Void arg)
+                throws AlgebricksException {
+            List<Mutable<ILogicalExpression>> newPrimaryKeyExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newPrimaryKeyExpressions, op.getPrimaryKeyExpressions());
+            List<Mutable<ILogicalExpression>> newSecondaryKeyExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newSecondaryKeyExpressions, op.getSecondaryKeyExpressions());
+            Mutable<ILogicalExpression> newFilterExpression = new MutableObject<ILogicalExpression>(((AbstractLogicalExpression)op.getFilterExpression())
+                    .cloneExpression());
+            return new IndexInsertDeleteOperator(op.getDataSourceIndex(), newPrimaryKeyExpressions,
+                    newSecondaryKeyExpressions, newFilterExpression, op.getOperation());
+        }
+
+        @Override
+        public ILogicalOperator visitSinkOperator(SinkOperator op, Void arg) throws AlgebricksException {
+            return new SinkOperator();
+        }
+
+        private void deepCopyExpressionRefs(List<Mutable<ILogicalExpression>> newExprs,
+                List<Mutable<ILogicalExpression>> oldExprs) {
+            for (Mutable<ILogicalExpression> oldExpr : oldExprs)
+                newExprs.add(new MutableObject<ILogicalExpression>(((AbstractLogicalExpression) oldExpr.getValue())
+                        .cloneExpression()));
+        }
+
+        private Mutable<ILogicalExpression> deepCopyExpressionRef(Mutable<ILogicalExpression> oldExpr) {
+            return new MutableObject<ILogicalExpression>(
+                    ((AbstractLogicalExpression) oldExpr.getValue()).cloneExpression());
+        }
+
+        private List<Pair<IOrder, Mutable<ILogicalExpression>>> deepCopyOrderAndExpression(
+                List<Pair<IOrder, Mutable<ILogicalExpression>>> ordersAndExprs) {
+            List<Pair<IOrder, Mutable<ILogicalExpression>>> newOrdersAndExprs = new ArrayList<Pair<IOrder, Mutable<ILogicalExpression>>>();
+            for (Pair<IOrder, Mutable<ILogicalExpression>> pair : ordersAndExprs)
+                newOrdersAndExprs.add(new Pair<IOrder, Mutable<ILogicalExpression>>(pair.first,
+                        deepCopyExpressionRef(pair.second)));
+            return newOrdersAndExprs;
+        }
+
+        @Override
+        public ILogicalOperator visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+            return new ExtensionOperator(op.getNewInstanceOfDelegateOperator());
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismUtilities.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismUtilities.java
new file mode 100644
index 0000000..02533c3
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismUtilities.java
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class IsomorphismUtilities {
+
+    public static void mapVariablesTopDown(ILogicalOperator op, ILogicalOperator arg,
+            Map<LogicalVariable, LogicalVariable> variableMapping) throws AlgebricksException {
+        IsomorphismVariableMappingVisitor visitor = new IsomorphismVariableMappingVisitor(variableMapping);
+        op.accept(visitor, arg);
+    }
+
+    public static boolean isOperatorIsomorphic(ILogicalOperator op, ILogicalOperator arg) throws AlgebricksException {
+        IsomorphismOperatorVisitor visitor = new IsomorphismOperatorVisitor();
+        return op.accept(visitor, arg).booleanValue();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
new file mode 100644
index 0000000..562bb4c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
@@ -0,0 +1,424 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractLogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractAssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class IsomorphismVariableMappingVisitor implements ILogicalOperatorVisitor<Void, ILogicalOperator> {
+
+    private Map<LogicalVariable, LogicalVariable> variableMapping;
+
+    public IsomorphismVariableMappingVisitor(Map<LogicalVariable, LogicalVariable> variableMapping) {
+        this.variableMapping = variableMapping;
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesForAbstractAssign(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesForAbstractAssign(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesForGroupBy(op, arg);
+        mapVariablesInNestedPlans(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        ILogicalOperator inputToCreator1 = op.getSourceOperator();
+        NestedTupleSourceOperator nts = (NestedTupleSourceOperator) arg;
+        ILogicalOperator inputToCreator2 = nts.getSourceOperator();
+        inputToCreator1.accept(this, inputToCreator2);
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesForAbstractAssign(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesInNestedPlans(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariablesForUnion(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+    private void mapChildren(ILogicalOperator op, ILogicalOperator opArg) throws AlgebricksException {
+        List<Mutable<ILogicalOperator>> inputs = op.getInputs();
+        List<Mutable<ILogicalOperator>> inputsArg = opArg.getInputs();
+        if (inputs.size() != inputsArg.size())
+            throw new AlgebricksException("children are not isomoprhic");
+        for (int i = 0; i < inputs.size(); i++) {
+            ILogicalOperator input = inputs.get(i).getValue();
+            ILogicalOperator inputArg = inputsArg.get(i).getValue();
+            input.accept(this, inputArg);
+        }
+    }
+
+    private void mapVariables(ILogicalOperator left, ILogicalOperator right) throws AlgebricksException {
+        List<LogicalVariable> producedVarLeft = new ArrayList<LogicalVariable>();
+        List<LogicalVariable> producedVarRight = new ArrayList<LogicalVariable>();
+        VariableUtilities.getProducedVariables(left, producedVarLeft);
+        VariableUtilities.getProducedVariables(right, producedVarRight);
+        mapVariables(producedVarLeft, producedVarRight);
+    }
+
+    private void mapVariables(List<LogicalVariable> variablesLeft, List<LogicalVariable> variablesRight) {
+        if (variablesLeft.size() != variablesRight.size())
+            return;
+        int size = variablesLeft.size();
+        for (int i = 0; i < size; i++) {
+            LogicalVariable left = variablesLeft.get(i);
+            LogicalVariable right = variablesRight.get(i);
+            variableMapping.put(right, left);
+        }
+    }
+
+    private void mapVariablesForAbstractAssign(ILogicalOperator left, ILogicalOperator right)
+            throws AlgebricksException {
+        AbstractAssignOperator leftOp = (AbstractAssignOperator) left;
+        AbstractAssignOperator rightOp = (AbstractAssignOperator) right;
+        List<LogicalVariable> producedVarLeft = new ArrayList<LogicalVariable>();
+        List<LogicalVariable> producedVarRight = new ArrayList<LogicalVariable>();
+        VariableUtilities.getProducedVariables(left, producedVarLeft);
+        VariableUtilities.getProducedVariables(right, producedVarRight);
+        mapVariablesForAbstractAssign(producedVarLeft, leftOp.getExpressions(), producedVarRight,
+                rightOp.getExpressions());
+    }
+
+    private void mapVariablesForGroupBy(ILogicalOperator left, ILogicalOperator right) throws AlgebricksException {
+        GroupByOperator leftOp = (GroupByOperator) left;
+        GroupByOperator rightOp = (GroupByOperator) right;
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> leftPairs = leftOp.getGroupByList();
+        List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> rightPairs = rightOp.getGroupByList();
+        mapVarExprPairList(leftPairs, rightPairs);
+        leftPairs = leftOp.getDecorList();
+        rightPairs = rightOp.getDecorList();
+        mapVarExprPairList(leftPairs, rightPairs);
+    }
+
+    private void mapVarExprPairList(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> leftPairs,
+            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> rightPairs) {
+        if (leftPairs.size() != rightPairs.size())
+            return;
+        for (int i = 0; i < leftPairs.size(); i++) {
+            ILogicalExpression exprLeft = leftPairs.get(i).second.getValue();
+            LogicalVariable leftVar = leftPairs.get(i).first;
+            for (int j = 0; j < leftPairs.size(); j++) {
+                ILogicalExpression exprRight = copyExpressionAndSubtituteVars(rightPairs.get(j).second).getValue();
+                if (exprLeft.equals(exprRight)) {
+                    LogicalVariable rightVar = rightPairs.get(j).first;
+                    if (rightVar != null && leftVar != null) {
+                        variableMapping.put(rightVar, leftVar);
+                    }
+                    break;
+                }
+            }
+        }
+    }
+
+    private void mapVariablesForAbstractAssign(List<LogicalVariable> variablesLeft,
+            List<Mutable<ILogicalExpression>> exprsLeft, List<LogicalVariable> variablesRight,
+            List<Mutable<ILogicalExpression>> exprsRight) {
+        if (variablesLeft.size() != variablesRight.size())
+            return;
+        int size = variablesLeft.size();
+        for (int i = 0; i < size; i++) {
+            ILogicalExpression exprLeft = exprsLeft.get(i).getValue();
+            LogicalVariable left = variablesLeft.get(i);
+            for (int j = 0; j < size; j++) {
+                ILogicalExpression exprRight = copyExpressionAndSubtituteVars(exprsRight.get(j)).getValue();
+                if (exprLeft.equals(exprRight)) {
+                    LogicalVariable right = variablesRight.get(j);
+                    variableMapping.put(right, left);
+                    break;
+                }
+            }
+        }
+    }
+
+    private void mapVariablesInNestedPlans(ILogicalOperator opOrigin, ILogicalOperator arg) throws AlgebricksException {
+        AbstractOperatorWithNestedPlans op = (AbstractOperatorWithNestedPlans) opOrigin;
+        AbstractOperatorWithNestedPlans argOp = (AbstractOperatorWithNestedPlans) arg;
+        List<ILogicalPlan> plans = op.getNestedPlans();
+        List<ILogicalPlan> plansArg = argOp.getNestedPlans();
+        if (plans.size() != plansArg.size())
+            return;
+        for (int i = 0; i < plans.size(); i++) {
+            List<Mutable<ILogicalOperator>> roots = plans.get(i).getRoots();
+            List<Mutable<ILogicalOperator>> rootsArg = plansArg.get(i).getRoots();
+            if (roots.size() != rootsArg.size())
+                return;
+            for (int j = 0; j < roots.size(); j++) {
+                ILogicalOperator topOp1 = roots.get(j).getValue();
+                ILogicalOperator topOp2 = rootsArg.get(j).getValue();
+                topOp1.accept(this, topOp2);
+            }
+        }
+    }
+
+    private void mapVariablesStandard(ILogicalOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapChildren(op, arg);
+        mapVariables(op, arg);
+    }
+
+    private Mutable<ILogicalExpression> copyExpressionAndSubtituteVars(Mutable<ILogicalExpression> expr) {
+        ILogicalExpression copy = ((AbstractLogicalExpression) expr.getValue()).cloneExpression();
+        for (Entry<LogicalVariable, LogicalVariable> entry : variableMapping.entrySet())
+            copy.substituteVar(entry.getKey(), entry.getValue());
+        return new MutableObject<ILogicalExpression>(copy);
+    }
+
+    private void mapVariablesForUnion(ILogicalOperator op, ILogicalOperator arg) {
+        UnionAllOperator union = (UnionAllOperator) op;
+        UnionAllOperator unionArg = (UnionAllOperator) arg;
+        mapVarTripleList(union.getVariableMappings(), unionArg.getVariableMappings());
+    }
+
+    private void mapVarTripleList(List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> leftTriples,
+            List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> rightTriples) {
+        if (leftTriples.size() != rightTriples.size())
+            return;
+        for (int i = 0; i < leftTriples.size(); i++) {
+            LogicalVariable leftFirstVar = leftTriples.get(i).first;
+            LogicalVariable leftSecondVar = leftTriples.get(i).second;
+            LogicalVariable leftThirdVar = leftTriples.get(i).third;
+            for (int j = 0; j < rightTriples.size(); j++) {
+                LogicalVariable rightFirstVar = rightTriples.get(j).first;
+                LogicalVariable rightSecondVar = rightTriples.get(j).second;
+                LogicalVariable rightThirdVar = rightTriples.get(j).third;
+                if (varEquivalent(leftFirstVar, rightFirstVar) && varEquivalent(leftSecondVar, rightSecondVar)) {
+                    variableMapping.put(rightThirdVar, leftThirdVar);
+                    break;
+                }
+            }
+        }
+    }
+
+    private boolean varEquivalent(LogicalVariable left, LogicalVariable right) {
+        if (variableMapping.get(right) == null)
+            return false;
+        if (variableMapping.get(right).equals(left))
+            return true;
+        else
+            return false;
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, ILogicalOperator arg) throws AlgebricksException {
+        mapVariablesStandard(op, arg);
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java
new file mode 100644
index 0000000..9b2f5a0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java
@@ -0,0 +1,328 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.OperatorAnnotations;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionEvalSizeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableEvalSizeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractAssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILogicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LogicalPropertiesVectorImpl;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+import edu.uci.ics.hyracks.algebricks.core.config.AlgebricksConfig;
+
+public class LogicalPropertiesVisitor implements ILogicalOperatorVisitor<Void, IOptimizationContext> {
+
+    public static void computeLogicalPropertiesDFS(ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        LogicalPropertiesVisitor visitor = new LogicalPropertiesVisitor();
+        computeLogicalPropertiesRec(op, visitor, context);
+    }
+
+    private static void computeLogicalPropertiesRec(ILogicalOperator op, LogicalPropertiesVisitor visitor,
+            IOptimizationContext context) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> ref : op.getInputs()) {
+            computeLogicalPropertiesRec(ref.getValue(), visitor, context);
+        }
+        op.accept(visitor, context);
+        if (AlgebricksConfig.DEBUG) {
+            AlgebricksConfig.ALGEBRICKS_LOGGER.finest("Logical properties visitor for " + op + ": "
+                    + context.getLogicalPropertiesVector(op) + "\n");
+        }
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, IOptimizationContext context) throws AlgebricksException {
+        visitAssignment(op, context);
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, IOptimizationContext arg) throws AlgebricksException {
+        propagateCardinalityAndFrameNumber(op, arg);
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, IOptimizationContext arg) throws AlgebricksException {
+        Object annot1 = op.getAnnotations().get(OperatorAnnotations.CARDINALITY);
+        if (annot1 == null) {
+            return null;
+        }
+        Integer m = (Integer) annot1;
+        LogicalPropertiesVectorImpl v = new LogicalPropertiesVectorImpl();
+        v.setNumberOfTuples(m);
+        Object annot2 = op.getAnnotations().get(OperatorAnnotations.MAX_NUMBER_FRAMES);
+        if (annot2 != null) {
+            Integer f = (Integer) annot2;
+            v.setMaxOutputFrames(f);
+        }
+        arg.putLogicalPropertiesVector(op, v);
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, IOptimizationContext context) throws AlgebricksException {
+        propagateCardinalityAndFrameNumber(op, context);
+        return null;
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        visitAssignment(op, context);
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    private LogicalPropertiesVectorImpl propagateCardinality(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        ILogicalPropertiesVector v0 = context.getLogicalPropertiesVector(op0);
+        if (v0 == null) {
+            return null;
+        }
+        LogicalPropertiesVectorImpl v = new LogicalPropertiesVectorImpl();
+        v.setNumberOfTuples(v0.getNumberOfTuples());
+        context.putLogicalPropertiesVector(op, v);
+        return v;
+    }
+
+    private void visitAssignment(AbstractAssignOperator op, IOptimizationContext context) throws AlgebricksException {
+        LogicalPropertiesVectorImpl v = propagateCardinality(op, context);
+        if (v != null && v.getNumberOfTuples() != null) {
+            IVariableEvalSizeEnvironment varSizeEnv = context.getVariableEvalSizeEnvironment();
+            IExpressionEvalSizeComputer evalSize = context.getExpressionEvalSizeComputer();
+            if (evalSize != null) {
+                ILogicalOperator op0 = op.getInputs().get(0).getValue();
+                ILogicalPropertiesVector v0 = context.getLogicalPropertiesVector(op0);
+                if (v0 != null) {
+                    long frames0 = v0.getMaxOutputFrames();
+                    long overhead = 0; // added per tuple
+                    for (Mutable<ILogicalExpression> exprRef : op.getExpressions()) {
+                        int sz = evalSize.getEvalSize(exprRef.getValue(), varSizeEnv);
+                        if (sz == -1) {
+                            return;
+                        }
+                        overhead += sz;
+                    }
+                    int frameSize = context.getFrameSize();
+                    if (frameSize > 0) {
+                        long sz = frames0 * frameSize + overhead * v.getNumberOfTuples();
+                        int frames1 = (int) (sz / frameSize);
+                        if (sz % frameSize > 0) {
+                            frames1++;
+                        }
+                        v.setMaxOutputFrames(frames1);
+                    }
+                }
+            }
+        }
+    }
+
+    public void propagateCardinalityAndFrameNumber(ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        LogicalPropertiesVectorImpl v = propagateCardinality(op, context);
+        // propagate also max number of frames (conservatively)
+        ILogicalOperator op0 = op.getInputs().get(0).getValue();
+        ILogicalPropertiesVector v0 = context.getLogicalPropertiesVector(op0);
+        if (v0 != null) {
+            v.setMaxOutputFrames(v0.getMaxOutputFrames());
+        }
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, IOptimizationContext arg) throws AlgebricksException {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java
new file mode 100644
index 0000000..994c6cb
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java
@@ -0,0 +1,254 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class ProducedVariableVisitor implements ILogicalOperatorVisitor<Void, Void> {
+
+    private Collection<LogicalVariable> producedVariables;
+
+    public ProducedVariableVisitor(Collection<LogicalVariable> producedVariables) throws AlgebricksException {
+        this.producedVariables = producedVariables;
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, Void arg) {
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, Void arg) throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getLiveVariables(r.getValue(), producedVariables);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : op.getGroupByList()) {
+            if (p.first != null) {
+                producedVariables.add(p.first);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : op.getDecorList()) {
+            if (p.first != null) {
+                producedVariables.add(p.first);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, Void arg) throws AlgebricksException {
+        List<LogicalVariable> usedVariables = new ArrayList<LogicalVariable>();
+        VariableUtilities.getUsedVariables(op, usedVariables);
+        for (LogicalVariable v : op.getOutputVariables()) {
+            if (!usedVariables.contains(v)) {
+                producedVariables.add(v);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, Void arg) throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getLiveVariables(r.getValue(), producedVariables);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, Void arg) throws AlgebricksException {
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : op.getVariableMappings()) {
+            producedVariables.add(t.third);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, Void arg) throws AlgebricksException {
+        producedVariables.addAll(op.getVariables());
+        LogicalVariable positionalVariable = op.getPositionalVariable();
+        if (positionalVariable != null) {
+            if (!producedVariables.contains(positionalVariable))
+                producedVariables.add(positionalVariable);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java
new file mode 100644
index 0000000..9295179
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java
@@ -0,0 +1,277 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.Collection;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class SchemaVariableVisitor implements ILogicalOperatorVisitor<Void, Void> {
+
+    private Collection<LogicalVariable> schemaVariables;
+
+    public SchemaVariableVisitor(Collection<LogicalVariable> schemaVariables) {
+        this.schemaVariables = schemaVariables;
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, Void arg) throws AlgebricksException {
+        schemaVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, Void arg) throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getLiveVariables(r.getValue(), schemaVariables);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : op.getGroupByList()) {
+            if (p.first != null) {
+                schemaVariables.add(p.first);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : op.getDecorList()) {
+            if (p.first != null) {
+                schemaVariables.add(p.first);
+            } else {
+                ILogicalExpression e = p.second.getValue();
+                if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                    schemaVariables.add(((VariableReferenceExpression) e).getVariableReference());
+                }
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Void arg) throws AlgebricksException {
+        VariableUtilities.getLiveVariables(op.getSourceOperator(), schemaVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, Void arg) throws AlgebricksException {
+        schemaVariables.addAll(op.getVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, Void arg) throws AlgebricksException {
+        // VariableUtilities.getProducedVariables(op, schemaVariables);
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, Void arg) throws AlgebricksException {
+        schemaVariables.addAll(op.getOutputVariables());
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, Void arg) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> c : op.getInputs()) {
+            VariableUtilities.getLiveVariables(c.getValue(), schemaVariables);
+        }
+        VariableUtilities.getProducedVariables(op, schemaVariables);
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getLiveVariables(r.getValue(), schemaVariables);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, Void arg) throws AlgebricksException {
+        VariableUtilities.getProducedVariables(op, schemaVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    private void standardLayout(ILogicalOperator op) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> c : op.getInputs()) {
+            VariableUtilities.getLiveVariables(c.getValue(), schemaVariables);
+        }
+        VariableUtilities.getProducedVariables(op, schemaVariables);
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java
new file mode 100644
index 0000000..11e56ca
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java
@@ -0,0 +1,419 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.util.OperatorManipulationUtil;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class SubstituteVariableVisitor implements ILogicalOperatorVisitor<Void, Pair<LogicalVariable, LogicalVariable>> {
+
+    private final boolean goThroughNts;
+    private final ITypingContext ctx;
+
+    public SubstituteVariableVisitor(boolean goThroughNts, ITypingContext ctx) {
+        this.goThroughNts = goThroughNts;
+        this.ctx = ctx;
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            if (variables.get(i).equals(pair.first)) {
+                variables.set(i, pair.second);
+            } else {
+                op.getExpressions().get(i).getValue().substituteVar(pair.first, pair.second);
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            if (variables.get(i).equals(pair.first)) {
+                variables.set(i, pair.second);
+            } else {
+                op.getExpressions().get(i).getValue().substituteVar(pair.first, pair.second);
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        for (int i = 0; i < variables.size(); i++) {
+            if (variables.get(i) == pair.first) {
+                variables.set(i, pair.second);
+                return null;
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (Mutable<ILogicalExpression> eRef : op.getExpressions()) {
+            eRef.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Pair<LogicalVariable, LogicalVariable> pair) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, Pair<LogicalVariable, LogicalVariable> pair) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        subst(pair.first, pair.second, op.getGroupByList());
+        subst(pair.first, pair.second, op.getDecorList());
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                OperatorManipulationUtil.substituteVarRec((AbstractLogicalOperator) r.getValue(), pair.first,
+                        pair.second, goThroughNts, ctx);
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getCondition().getValue().substituteVar(pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getCondition().getValue().substituteVar(pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getMaxObjects().getValue().substituteVar(pair.first, pair.second);
+        ILogicalExpression offset = op.getOffset().getValue();
+        if (offset != null) {
+            offset.substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getAfterObjects().getValue().substituteVar(pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (Pair<IOrder, Mutable<ILogicalExpression>> oe : op.getOrderExpressions()) {
+            oe.second.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (Mutable<ILogicalExpression> e : op.getExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> usedVariables = op.getVariables();
+        int n = usedVariables.size();
+        for (int i = 0; i < n; i++) {
+            LogicalVariable v = usedVariables.get(i);
+            if (v.equals(pair.first)) {
+                usedVariables.set(i, pair.second);
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        int n = variables.size();
+        for (int i = 0; i < n; i++) {
+            if (variables.get(i).equals(pair.first)) {
+                variables.set(i, pair.second);
+            } else {
+                op.getExpressions().get(i).getValue().substituteVar(pair.first, pair.second);
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        substInArray(op.getInputVariables(), pair.first, pair.second);
+        substInArray(op.getOutputVariables(), pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, Pair<LogicalVariable, LogicalVariable> pair) {
+        op.getCondition().getValue().substituteVar(pair.first, pair.second);
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                OperatorManipulationUtil.substituteVarRec((AbstractLogicalOperator) r.getValue(), pair.first,
+                        pair.second, goThroughNts, ctx);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> varMap = op.getVariableMappings();
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : varMap) {
+            if (t.first.equals(pair.first)) {
+                t.first = pair.second;
+            }
+            if (t.second.equals(pair.first)) {
+                t.second = pair.second;
+            }
+            if (t.third.equals(pair.first)) {
+                t.third = pair.second;
+            }
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        for (int i = 0; i < variables.size(); i++) {
+            if (variables.get(i) == pair.first) {
+                variables.set(i, pair.second);
+                return null;
+            }
+        }
+        op.getExpressionRef().getValue().substituteVar(pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        List<LogicalVariable> variables = op.getVariables();
+        for (int i = 0; i < variables.size(); i++) {
+            if (variables.get(i) == pair.first) {
+                variables.set(i, pair.second);
+                return null;
+            }
+        }
+        op.getExpressionRef().getValue().substituteVar(pair.first, pair.second);
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (Mutable<ILogicalExpression> e : op.getExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getPayloadExpression().getValue().substituteVar(pair.first, pair.second);
+        for (Mutable<ILogicalExpression> e : op.getKeyExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    private void subst(LogicalVariable v1, LogicalVariable v2,
+            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> varExprPairList) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : varExprPairList) {
+            if (ve.first != null && ve.first.equals(v1)) {
+                ve.first = v2;
+                return;
+            }
+            ve.second.getValue().substituteVar(v1, v2);
+        }
+    }
+
+    private void substInArray(ArrayList<LogicalVariable> varArray, LogicalVariable v1, LogicalVariable v2) {
+        for (int i = 0; i < varArray.size(); i++) {
+            LogicalVariable v = varArray.get(i);
+            if (v == v1) {
+                varArray.set(i, v2);
+            }
+        }
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, Pair<LogicalVariable, LogicalVariable> arg)
+            throws AlgebricksException {
+        op.substituteVar(arg.first, arg.second);
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        op.getPayloadExpression().getValue().substituteVar(pair.first, pair.second);
+        for (Mutable<ILogicalExpression> e : op.getPrimaryKeyExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        for (Mutable<ILogicalExpression> e : op.getPrimaryKeyExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        for (Mutable<ILogicalExpression> e : op.getSecondaryKeyExpressions()) {
+            e.getValue().substituteVar(pair.first, pair.second);
+        }
+        substVarTypes(op, pair);
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, Pair<LogicalVariable, LogicalVariable> pair)
+            throws AlgebricksException {
+        return null;
+    }
+
+    private void substVarTypes(ILogicalOperator op, Pair<LogicalVariable, LogicalVariable> arg)
+            throws AlgebricksException {
+        if (ctx == null) {
+            return;
+        }
+        IVariableTypeEnvironment env = ctx.getOutputTypeEnvironment(op);
+        env.substituteProducedVariable(arg.first, arg.second);
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, Pair<LogicalVariable, LogicalVariable> arg)
+            throws AlgebricksException {
+        return null;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java
new file mode 100644
index 0000000..3a82ccd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java
@@ -0,0 +1,303 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.Collection;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class UsedVariableVisitor implements ILogicalOperatorVisitor<Void, Void> {
+
+    private Collection<LogicalVariable> usedVariables;
+
+    public UsedVariableVisitor(Collection<LogicalVariable> usedVariables) {
+        this.usedVariables = usedVariables;
+    }
+
+    @Override
+    public Void visitAggregateOperator(AggregateOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> exprRef : op.getExpressions()) {
+            exprRef.getValue().getUsedVariables(usedVariables);
+        }
+        if (op.getPartitioningVariable() != null) {
+            usedVariables.add(op.getPartitioningVariable());
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitAssignOperator(AssignOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> exprRef : op.getExpressions()) {
+            exprRef.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitDataScanOperator(DataSourceScanOperator op, Void arg) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitDistinctOperator(DistinctOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> eRef : op.getExpressions()) {
+            eRef.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Void arg) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitExchangeOperator(ExchangeOperator op, Void arg) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitGroupByOperator(GroupByOperator op, Void arg) throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getUsedVariablesInDescendantsAndSelf(r.getValue(), usedVariables);
+            }
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> g : op.getGroupByList()) {
+            g.second.getValue().getUsedVariables(usedVariables);
+        }
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> g : op.getDecorList()) {
+            g.second.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitInnerJoinOperator(InnerJoinOperator op, Void arg) {
+        op.getCondition().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Void arg) {
+        op.getCondition().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitLimitOperator(LimitOperator op, Void arg) {
+        op.getMaxObjects().getValue().getUsedVariables(usedVariables);
+        ILogicalExpression offsetExpr = op.getOffset().getValue();
+        if (offsetExpr != null) {
+            offsetExpr.getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitDieOperator(DieOperator op, Void arg) {
+        op.getAfterObjects().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Void arg) {
+        // does not use any variable
+        return null;
+    }
+
+    @Override
+    public Void visitOrderOperator(OrderOperator op, Void arg) {
+        for (Pair<IOrder, Mutable<ILogicalExpression>> oe : op.getOrderExpressions()) {
+            oe.second.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitPartitioningSplitOperator(PartitioningSplitOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> e : op.getExpressions()) {
+            e.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitProjectOperator(ProjectOperator op, Void arg) {
+        List<LogicalVariable> parameterVariables = op.getVariables();
+        for (LogicalVariable v : parameterVariables) {
+            if (!usedVariables.contains(v)) {
+                usedVariables.add(v);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitRunningAggregateOperator(RunningAggregateOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> exprRef : op.getExpressions()) {
+            exprRef.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitScriptOperator(ScriptOperator op, Void arg) {
+        List<LogicalVariable> parameterVariables = op.getInputVariables();
+        for (LogicalVariable v : parameterVariables) {
+            if (!usedVariables.contains(v)) {
+                usedVariables.add(v);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitSelectOperator(SelectOperator op, Void arg) {
+        op.getCondition().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitSubplanOperator(SubplanOperator op, Void arg) throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                VariableUtilities.getUsedVariablesInDescendantsAndSelf(r.getValue(), usedVariables);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnionOperator(UnionAllOperator op, Void arg) {
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> m : op.getVariableMappings()) {
+            if (!usedVariables.contains(m.first)) {
+                usedVariables.add(m.first);
+            }
+            if (!usedVariables.contains(m.second)) {
+                usedVariables.add(m.second);
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestMapOperator(UnnestMapOperator op, Void arg) {
+        op.getExpressionRef().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitUnnestOperator(UnnestOperator op, Void arg) {
+        op.getExpressionRef().getValue().getUsedVariables(usedVariables);
+        return null;
+    }
+
+    @Override
+    public Void visitWriteOperator(WriteOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> expr : op.getExpressions()) {
+            expr.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitWriteResultOperator(WriteResultOperator op, Void arg) {
+        op.getPayloadExpression().getValue().getUsedVariables(usedVariables);
+        for (Mutable<ILogicalExpression> e : op.getKeyExpressions()) {
+            e.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitInsertDeleteOperator(InsertDeleteOperator op, Void arg) {
+        op.getPayloadExpression().getValue().getUsedVariables(usedVariables);
+        for (Mutable<ILogicalExpression> e : op.getPrimaryKeyExpressions()) {
+            e.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Void arg) {
+        for (Mutable<ILogicalExpression> e : op.getPrimaryKeyExpressions()) {
+            e.getValue().getUsedVariables(usedVariables);
+        }
+        for (Mutable<ILogicalExpression> e : op.getSecondaryKeyExpressions()) {
+            e.getValue().getUsedVariables(usedVariables);
+        }
+        return null;
+    }
+
+    @Override
+    public Void visitSinkOperator(SinkOperator op, Void arg) {
+        return null;
+    }
+
+    @Override
+    public Void visitReplicateOperator(ReplicateOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
+    public Void visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java
new file mode 100644
index 0000000..25f22e7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class VariableUtilities {
+
+    public static void getUsedVariables(ILogicalOperator op, Collection<LogicalVariable> usedVariables)
+            throws AlgebricksException {
+        ILogicalOperatorVisitor<Void, Void> visitor = new UsedVariableVisitor(usedVariables);
+        op.accept(visitor, null);
+    }
+
+    public static void getProducedVariables(ILogicalOperator op, Collection<LogicalVariable> producedVariables)
+            throws AlgebricksException {
+        ILogicalOperatorVisitor<Void, Void> visitor = new ProducedVariableVisitor(producedVariables);
+        op.accept(visitor, null);
+    }
+
+    public static void getLiveVariables(ILogicalOperator op, Collection<LogicalVariable> schemaVariables)
+            throws AlgebricksException {
+        ILogicalOperatorVisitor<Void, Void> visitor = new SchemaVariableVisitor(schemaVariables);
+        op.accept(visitor, null);
+    }
+
+    public static void getUsedVariablesInDescendantsAndSelf(ILogicalOperator op, Collection<LogicalVariable> vars)
+            throws AlgebricksException {
+        // DFS traversal
+        VariableUtilities.getUsedVariables(op, vars);
+        for (Mutable<ILogicalOperator> c : op.getInputs()) {
+            getUsedVariablesInDescendantsAndSelf(c.getValue(), vars);
+        }
+    }
+
+    public static void substituteVariables(ILogicalOperator op, LogicalVariable v1, LogicalVariable v2,
+            ITypingContext ctx) throws AlgebricksException {
+        substituteVariables(op, v1, v2, true, ctx);
+    }
+
+    public static void substituteVariables(ILogicalOperator op, LogicalVariable v1, LogicalVariable v2,
+            boolean goThroughNts, ITypingContext ctx) throws AlgebricksException {
+        ILogicalOperatorVisitor<Void, Pair<LogicalVariable, LogicalVariable>> visitor = new SubstituteVariableVisitor(
+                goThroughNts, ctx);
+        op.accept(visitor, new Pair<LogicalVariable, LogicalVariable>(v1, v2));
+    }
+
+    public static <T> boolean varListEqualUnordered(List<T> var, List<T> varArg) {
+        Set<T> varSet = new HashSet<T>();
+        Set<T> varArgSet = new HashSet<T>();
+        varSet.addAll(var);
+        varArgSet.addAll(varArg);
+        return varSet.equals(varArgSet);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractExchangePOperator.java
new file mode 100644
index 0000000..0aa9cd4
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractExchangePOperator.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+
+public abstract class AbstractExchangePOperator extends AbstractPhysicalOperator {
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        Pair<IConnectorDescriptor, TargetConstraint> connPair = createConnectorDescriptor(builder.getJobSpec(), op,
+                opSchema, context);
+        builder.contributeConnectorWithTargetConstraint(op, connPair.first, connPair.second);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    public abstract Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(
+            IConnectorDescriptorRegistry spec, ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context)
+            throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractHashJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractHashJoinPOperator.java
new file mode 100644
index 0000000..f188265
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractHashJoinPOperator.java
@@ -0,0 +1,191 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator.JoinKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.BroadcastPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+
+public abstract class AbstractHashJoinPOperator extends AbstractJoinPOperator {
+
+    protected List<LogicalVariable> keysLeftBranch;
+    protected List<LogicalVariable> keysRightBranch;
+
+    public AbstractHashJoinPOperator(JoinKind kind, JoinPartitioningType partitioningType,
+            List<LogicalVariable> sideLeftOfEqualities, List<LogicalVariable> sideRightOfEqualities) {
+        super(kind, partitioningType);
+        this.keysLeftBranch = sideLeftOfEqualities;
+        this.keysRightBranch = sideRightOfEqualities;
+    }
+
+    public List<LogicalVariable> getKeysLeftBranch() {
+        return keysLeftBranch;
+    }
+
+    public List<LogicalVariable> getKeysRightBranch() {
+        return keysRightBranch;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator iop, IOptimizationContext context)
+            throws AlgebricksException {
+        IPartitioningProperty pp;
+        AbstractLogicalOperator op = (AbstractLogicalOperator) iop;
+
+        if (op.getExecutionMode() == AbstractLogicalOperator.ExecutionMode.PARTITIONED) {
+            AbstractLogicalOperator op0 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+            IPhysicalPropertiesVector pv0 = op0.getPhysicalOperator().getDeliveredProperties();
+            AbstractLogicalOperator op1 = (AbstractLogicalOperator) op.getInputs().get(1).getValue();
+            IPhysicalPropertiesVector pv1 = op1.getPhysicalOperator().getDeliveredProperties();
+
+            if (pv0 == null || pv1 == null) {
+                pp = null;
+            } else {
+                pp = pv0.getPartitioningProperty();
+            }
+        } else {
+            pp = IPartitioningProperty.UNPARTITIONED;
+        }
+        this.deliveredProperties = new StructuralPropertiesVector(pp, deliveredLocalProperties(iop, context));
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator iop,
+            IPhysicalPropertiesVector reqdByParent) {
+        StructuralPropertiesVector[] pv = new StructuralPropertiesVector[2];
+        // In a cost-based optimizer, we would also try to propagate the
+        // parent's partitioning requirements.
+        AbstractLogicalOperator op = (AbstractLogicalOperator) iop;
+
+        IPartitioningProperty pp1 = null;
+        IPartitioningProperty pp2 = null;
+        if (op.getExecutionMode() == AbstractLogicalOperator.ExecutionMode.PARTITIONED) {
+            switch (partitioningType) {
+                case PAIRWISE: {
+                    pp1 = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(keysLeftBranch), null);
+                    pp2 = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(keysRightBranch), null);
+                    break;
+                }
+                case BROADCAST: {
+                    pp2 = new BroadcastPartitioningProperty(null);
+                    break;
+                }
+                default: {
+                    throw new IllegalStateException();
+                }
+            }
+        }
+
+        pv[0] = new StructuralPropertiesVector(pp1, null);
+        pv[1] = new StructuralPropertiesVector(pp2, null);
+
+        IPartitioningRequirementsCoordinator prc;
+        switch (kind) {
+            case INNER: {
+                prc = IPartitioningRequirementsCoordinator.EQCLASS_PARTITIONING_COORDINATOR;
+                break;
+            }
+            case LEFT_OUTER: {
+                prc = new IPartitioningRequirementsCoordinator() {
+
+                    @Override
+                    public Pair<Boolean, IPartitioningProperty> coordinateRequirements(
+                            IPartitioningProperty requirements, IPartitioningProperty firstDeliveredPartitioning,
+                            ILogicalOperator op, IOptimizationContext context) throws AlgebricksException {
+                        if (firstDeliveredPartitioning != null
+                                && firstDeliveredPartitioning.getPartitioningType() == requirements
+                                        .getPartitioningType()) {
+                            switch (requirements.getPartitioningType()) {
+                                case UNORDERED_PARTITIONED: {
+                                    UnorderedPartitionedProperty upp1 = (UnorderedPartitionedProperty) firstDeliveredPartitioning;
+                                    Set<LogicalVariable> set1 = upp1.getColumnSet();
+                                    UnorderedPartitionedProperty uppreq = (UnorderedPartitionedProperty) requirements;
+                                    Set<LogicalVariable> modifuppreq = new ListSet<LogicalVariable>();
+                                    Map<LogicalVariable, EquivalenceClass> eqmap = context.getEquivalenceClassMap(op);
+                                    Set<LogicalVariable> covered = new ListSet<LogicalVariable>();
+                                    for (LogicalVariable r : uppreq.getColumnSet()) {
+                                        EquivalenceClass ecSnd = eqmap.get(r);
+                                        boolean found = false;
+                                        int j = 0;
+                                        for (LogicalVariable rvar : keysRightBranch) {
+                                            if (rvar == r || ecSnd != null && eqmap.get(rvar) == ecSnd) {
+                                                found = true;
+                                                break;
+                                            }
+                                            j++;
+                                        }
+                                        if (!found) {
+                                            throw new IllegalStateException("Did not find a variable equivalent to "
+                                                    + r + " among " + keysRightBranch);
+                                        }
+                                        LogicalVariable v2 = keysLeftBranch.get(j);
+                                        EquivalenceClass ecFst = eqmap.get(v2);
+                                        for (LogicalVariable vset1 : set1) {
+                                            if (vset1 == v2 || ecFst != null && eqmap.get(vset1) == ecFst) {
+                                                covered.add(vset1);
+                                                modifuppreq.add(r);
+                                                break;
+                                            }
+                                        }
+                                    }
+                                    if (!covered.equals(set1)) {
+                                        throw new AlgebricksException("Could not modify " + requirements
+                                                + " to agree with partitioning property " + firstDeliveredPartitioning
+                                                + " delivered by previous input operator.");
+                                    }
+                                    UnorderedPartitionedProperty upp2 = new UnorderedPartitionedProperty(modifuppreq,
+                                            requirements.getNodeDomain());
+                                    return new Pair<Boolean, IPartitioningProperty>(false, upp2);
+                                }
+                                case ORDERED_PARTITIONED: {
+                                    throw new NotImplementedException();
+                                }
+                            }
+                        }
+                        return new Pair<Boolean, IPartitioningProperty>(true, requirements);
+                    }
+                };
+                break;
+            }
+            default: {
+                throw new IllegalStateException();
+            }
+        }
+
+        return new PhysicalRequirements(pv, prc);
+    }
+
+    protected abstract List<ILocalStructuralProperty> deliveredLocalProperties(ILogicalOperator op,
+            IOptimizationContext context) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractJoinPOperator.java
new file mode 100644
index 0000000..68e3a51
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractJoinPOperator.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator.JoinKind;
+
+public abstract class AbstractJoinPOperator extends AbstractPhysicalOperator {
+
+    public enum JoinPartitioningType {
+        PAIRWISE, BROADCAST
+    }
+
+    protected final JoinKind kind;
+    protected final JoinPartitioningType partitioningType;
+
+    public AbstractJoinPOperator(JoinKind kind, JoinPartitioningType partitioningType) {
+        this.kind = kind;
+        this.partitioningType = partitioningType;
+    }
+
+    public JoinKind getKind() {
+        return kind;
+    }
+
+    public JoinPartitioningType getPartitioningType() {
+        return partitioningType;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPhysicalOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPhysicalOperator.java
new file mode 100644
index 0000000..c5f4c71
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPhysicalOperator.java
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksCountPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.PlanCompiler;
+import edu.uci.ics.hyracks.algebricks.runtime.base.AlgebricksPipeline;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.meta.AlgebricksMetaOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.OperatorDescriptorId;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public abstract class AbstractPhysicalOperator implements IPhysicalOperator {
+
+    protected IPhysicalPropertiesVector deliveredProperties;
+    private boolean disableJobGenBelow = false;
+    private Object hostQueryContext;
+
+    @Override
+    public final IPhysicalPropertiesVector getDeliveredProperties() {
+        return deliveredProperties;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString();
+    }
+
+    public void setHostQueryContext(Object context) {
+        this.hostQueryContext = context;
+    }
+
+    public Object getHostQueryContext() {
+        return hostQueryContext;
+    }
+
+    protected PhysicalRequirements emptyUnaryRequirements() {
+        StructuralPropertiesVector[] req = new StructuralPropertiesVector[] { StructuralPropertiesVector.EMPTY_PROPERTIES_VECTOR };
+        return new PhysicalRequirements(req, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void disableJobGenBelowMe() {
+        this.disableJobGenBelow = true;
+    }
+
+    @Override
+    public boolean isJobGenDisabledBelowMe() {
+        return disableJobGenBelow;
+    }
+
+    protected void contributeOpDesc(IHyracksJobBuilder builder, AbstractLogicalOperator op, IOperatorDescriptor opDesc) {
+        if (op.getExecutionMode() == ExecutionMode.UNPARTITIONED) {
+            AlgebricksPartitionConstraint apc = new AlgebricksCountPartitionConstraint(1);
+            builder.contributeAlgebricksPartitionConstraint(opDesc, apc);
+        }
+        builder.contributeHyracksOperator(op, opDesc);
+    }
+
+    protected AlgebricksPipeline[] compileSubplans(IOperatorSchema outerPlanSchema,
+            AbstractOperatorWithNestedPlans npOp, IOperatorSchema opSchema, JobGenContext context)
+            throws AlgebricksException {
+        AlgebricksPipeline[] subplans = new AlgebricksPipeline[npOp.getNestedPlans().size()];
+        PlanCompiler pc = new PlanCompiler(context);
+        int i = 0;
+        for (ILogicalPlan p : npOp.getNestedPlans()) {
+            subplans[i++] = buildPipelineWithProjection(p, outerPlanSchema, npOp, opSchema, pc);
+        }
+        return subplans;
+    }
+
+    private AlgebricksPipeline buildPipelineWithProjection(ILogicalPlan p, IOperatorSchema outerPlanSchema,
+            AbstractOperatorWithNestedPlans npOp, IOperatorSchema opSchema, PlanCompiler pc) throws AlgebricksException {
+        if (p.getRoots().size() > 1) {
+            throw new NotImplementedException("Nested plans with several roots are not supported.");
+        }
+        JobSpecification nestedJob = pc.compilePlan(p, outerPlanSchema);
+        ILogicalOperator topOpInSubplan = p.getRoots().get(0).getValue();
+        JobGenContext context = pc.getContext();
+        IOperatorSchema topOpInSubplanScm = context.getSchema(topOpInSubplan);
+        opSchema.addAllVariables(topOpInSubplanScm);
+
+        Map<OperatorDescriptorId, IOperatorDescriptor> opMap = nestedJob.getOperatorMap();
+        if (opMap.size() != 1) {
+            throw new AlgebricksException(
+                    "Attempting to construct a nested plan with "
+                            + opMap.size()
+                            + " operator descriptors. Currently, nested plans can only consist in linear pipelines of Asterix micro operators.");
+        }
+
+        for (OperatorDescriptorId oid : opMap.keySet()) {
+            IOperatorDescriptor opd = opMap.get(oid);
+            if (!(opd instanceof AlgebricksMetaOperatorDescriptor)) {
+                throw new AlgebricksException(
+                        "Can only generate Hyracks jobs for pipelinable Asterix nested plans, not for "
+                                + opd.getClass().getName());
+            }
+            AlgebricksMetaOperatorDescriptor amod = (AlgebricksMetaOperatorDescriptor) opd;
+
+            return amod.getPipeline();
+            // we suppose that the top operator in the subplan already does the
+            // projection for us
+        }
+
+        throw new IllegalStateException();
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java
new file mode 100644
index 0000000..7dd6372
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPreclusteredGroupByPOperator.java
@@ -0,0 +1,238 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalGroupingProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PropertiesUtil;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+
+public abstract class AbstractPreclusteredGroupByPOperator extends AbstractPhysicalOperator {
+
+    protected List<LogicalVariable> columnList;
+
+    public AbstractPreclusteredGroupByPOperator(List<LogicalVariable> columnList) {
+        this.columnList = columnList;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + columnList;
+    }
+
+    public List<LogicalVariable> getGbyColumns() {
+        return columnList;
+    }
+
+    public void setGbyColumns(List<LogicalVariable> gByColumns) {
+        this.columnList = gByColumns;
+    }
+
+    // Obs: We don't propagate properties corresponding to decors, since they
+    // are func. dep. on the group-by variables.
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        List<ILocalStructuralProperty> propsLocal = new LinkedList<ILocalStructuralProperty>();
+        GroupByOperator gby = (GroupByOperator) op;
+        ILogicalOperator op2 = gby.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector childProp = op2.getDeliveredPhysicalProperties();
+        IPartitioningProperty pp = childProp.getPartitioningProperty();
+        List<ILocalStructuralProperty> childLocals = childProp.getLocalProperties();
+        if (childLocals != null) {
+            for (ILocalStructuralProperty lsp : childLocals) {
+                boolean failed = false;
+                switch (lsp.getPropertyType()) {
+                    case LOCAL_GROUPING_PROPERTY: {
+                        LocalGroupingProperty lgp = (LocalGroupingProperty) lsp;
+                        Set<LogicalVariable> colSet = new ListSet<LogicalVariable>();
+                        for (LogicalVariable v : lgp.getColumnSet()) {
+                            LogicalVariable v2 = getLhsGbyVar(gby, v);
+                            if (v2 != null) {
+                                colSet.add(v2);
+                            } else {
+                                failed = true;
+                            }
+                        }
+                        if (!failed) {
+                            propsLocal.add(new LocalGroupingProperty(colSet));
+                        }
+                        break;
+                    }
+                    case LOCAL_ORDER_PROPERTY: {
+                        LocalOrderProperty lop = (LocalOrderProperty) lsp;
+                        OrderColumn oc = lop.getOrderColumn();
+                        LogicalVariable v2 = getLhsGbyVar(gby, oc.getColumn());
+                        if (v2 != null) {
+                            propsLocal.add(new LocalOrderProperty(new OrderColumn(v2, oc.getOrder())));
+                        } else {
+                            failed = true;
+                        }
+                        break;
+                    }
+                    default: {
+                        throw new IllegalStateException();
+                    }
+                }
+                if (failed) {
+                    break;
+                }
+            }
+        }
+        deliveredProperties = new StructuralPropertiesVector(pp, propsLocal);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+        List<ILocalStructuralProperty> localProps = null;
+
+        localProps = new ArrayList<ILocalStructuralProperty>(1);
+        Set<LogicalVariable> gbvars = new ListSet<LogicalVariable>(columnList);
+        LocalGroupingProperty groupProp = new LocalGroupingProperty(gbvars, new ArrayList<LogicalVariable>(columnList));
+
+        GroupByOperator gby = (GroupByOperator) op;
+        boolean goon = true;
+        for (ILogicalPlan p : gby.getNestedPlans()) {
+            // try to propagate secondary order requirements from nested
+            // groupings
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                AbstractLogicalOperator op1 = (AbstractLogicalOperator) r.getValue();
+                if (op1.getOperatorTag() == LogicalOperatorTag.AGGREGATE) {
+                    AbstractLogicalOperator op2 = (AbstractLogicalOperator) op1.getInputs().get(0).getValue();
+                    IPhysicalOperator pop2 = op2.getPhysicalOperator();
+                    if (pop2 instanceof AbstractPreclusteredGroupByPOperator) {
+                        List<LogicalVariable> sndOrder = ((AbstractPreclusteredGroupByPOperator) pop2).getGbyColumns();
+                        groupProp.getColumnSet().addAll(sndOrder);
+                        groupProp.getPreferredOrderEnforcer().addAll(sndOrder);
+                        goon = false;
+                        break;
+                    }
+                }
+            }
+            if (!goon) {
+                break;
+            }
+        }
+
+        localProps.add(groupProp);
+
+        if (reqdByParent != null) {
+            // propagate parent requirements
+            List<ILocalStructuralProperty> lpPar = reqdByParent.getLocalProperties();
+            if (lpPar != null) {
+                boolean allOk = true;
+                List<ILocalStructuralProperty> props = new ArrayList<ILocalStructuralProperty>(lpPar.size());
+                for (ILocalStructuralProperty prop : lpPar) {
+                    if (prop.getPropertyType() != PropertyType.LOCAL_ORDER_PROPERTY) {
+                        allOk = false;
+                        break;
+                    }
+                    LocalOrderProperty lop = (LocalOrderProperty) prop;
+                    LogicalVariable ord = lop.getColumn();
+                    Pair<LogicalVariable, Mutable<ILogicalExpression>> p = getGbyPairByRhsVar(gby, ord);
+                    if (p == null) {
+                        p = getDecorPairByRhsVar(gby, ord);
+                        if (p == null) {
+                            allOk = false;
+                            break;
+                        }
+                    }
+                    ILogicalExpression e = p.second.getValue();
+                    if (e.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                        throw new IllegalStateException(
+                                "Right hand side of group-by assignment should have been normalized to a variable reference.");
+                    }
+                    LogicalVariable v = ((VariableReferenceExpression) e).getVariableReference();
+                    props.add(new LocalOrderProperty(new OrderColumn(v, lop.getOrder())));
+                }
+                List<FunctionalDependency> fdList = new ArrayList<FunctionalDependency>();
+                for (Pair<LogicalVariable, Mutable<ILogicalExpression>> decorPair : gby.getDecorList()) {
+                    List<LogicalVariable> hd = gby.getGbyVarList();
+                    List<LogicalVariable> tl = new ArrayList<LogicalVariable>(1);
+                    tl.add(((VariableReferenceExpression) decorPair.second.getValue()).getVariableReference());
+                    fdList.add(new FunctionalDependency(hd, tl));
+                }
+                if (allOk
+                        && PropertiesUtil.matchLocalProperties(localProps, props,
+                                new HashMap<LogicalVariable, EquivalenceClass>(), fdList)) {
+                    localProps = props;
+                }
+            }
+        }
+
+        IPartitioningProperty pp = null;
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) op;
+        if (aop.getExecutionMode() == ExecutionMode.PARTITIONED) {
+            pp = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(columnList), null);
+        }
+        pv[0] = new StructuralPropertiesVector(pp, localProps);
+        return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    private static Pair<LogicalVariable, Mutable<ILogicalExpression>> getGbyPairByRhsVar(GroupByOperator gby,
+            LogicalVariable var) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : gby.getGroupByList()) {
+            if (ve.first == var) {
+                return ve;
+            }
+        }
+        return null;
+    }
+
+    private static Pair<LogicalVariable, Mutable<ILogicalExpression>> getDecorPairByRhsVar(GroupByOperator gby,
+            LogicalVariable var) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : gby.getDecorList()) {
+            if (ve.first == var) {
+                return ve;
+            }
+        }
+        return null;
+    }
+
+    private static LogicalVariable getLhsGbyVar(GroupByOperator gby, LogicalVariable var) {
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> ve : gby.getGroupByList()) {
+            ILogicalExpression e = ve.second.getValue();
+            if (e.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new IllegalStateException(
+                        "Right hand side of group by assignment should have been normalized to a variable reference.");
+            }
+            LogicalVariable v = ((VariableReferenceExpression) e).getVariableReference();
+            if (v == var) {
+                return ve.first;
+            }
+        }
+        return null;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPropagatePropertiesForUsedVariablesPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPropagatePropertiesForUsedVariablesPOperator.java
new file mode 100644
index 0000000..224d94c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractPropagatePropertiesForUsedVariablesPOperator.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+
+public abstract class AbstractPropagatePropertiesForUsedVariablesPOperator extends AbstractPhysicalOperator {
+
+    public void computeDeliveredPropertiesForUsedVariables(ILogicalOperator op, List<LogicalVariable> usedVariables) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        IPartitioningProperty pp = op2.getDeliveredPhysicalProperties().getPartitioningProperty();
+        List<ILocalStructuralProperty> downPropsLocal = op2.getDeliveredPhysicalProperties().getLocalProperties();
+        List<ILocalStructuralProperty> propsLocal = new ArrayList<ILocalStructuralProperty>();
+        for (ILocalStructuralProperty lsp : downPropsLocal) {
+            LinkedList<LogicalVariable> cols = new LinkedList<LogicalVariable>();
+            lsp.getColumns(cols);
+            if (usedVariables.containsAll(cols)) {
+                propsLocal.add(lsp);
+            }
+        }
+        deliveredProperties = new StructuralPropertiesVector(pp, propsLocal);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractScanPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractScanPOperator.java
new file mode 100644
index 0000000..347d580
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractScanPOperator.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+
+public abstract class AbstractScanPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractStableSortPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractStableSortPOperator.java
new file mode 100644
index 0000000..63ea8b9
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AbstractStableSortPOperator.java
@@ -0,0 +1,130 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+
+public abstract class AbstractStableSortPOperator extends AbstractPhysicalOperator {
+
+    protected OrderColumn[] sortColumns;
+    protected List<ILocalStructuralProperty> orderProps;
+
+    public AbstractStableSortPOperator() {
+    }
+
+    public OrderColumn[] getSortColumns() {
+        return sortColumns;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        // if (orderProps == null) { // to do caching, we need some mechanism to
+        // invalidate cache
+        computeLocalProperties(op);
+        // }
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        StructuralPropertiesVector childProp = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties();
+        deliveredProperties = new StructuralPropertiesVector(childProp.getPartitioningProperty(), orderProps);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator iop,
+            IPhysicalPropertiesVector reqdByParent) {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) iop;
+        if (op.getExecutionMode() == AbstractLogicalOperator.ExecutionMode.PARTITIONED) {
+            if (orderProps == null) {
+                computeLocalProperties(op);
+            }
+            StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(
+                    IPartitioningProperty.UNPARTITIONED, orderProps) };
+            return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+        } else {
+            return emptyUnaryRequirements();
+        }
+    }
+
+    public void computeLocalProperties(ILogicalOperator op) {
+        orderProps = new LinkedList<ILocalStructuralProperty>();
+
+        OrderOperator ord = (OrderOperator) op;
+        for (Pair<IOrder, Mutable<ILogicalExpression>> p : ord.getOrderExpressions()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression varRef = (VariableReferenceExpression) expr;
+                LogicalVariable var = varRef.getVariableReference();
+                switch (p.first.getKind()) {
+                    case ASC: {
+                        orderProps.add(new LocalOrderProperty(new OrderColumn(var, OrderKind.ASC)));
+                        break;
+                    }
+                    case DESC: {
+                        orderProps.add(new LocalOrderProperty(new OrderColumn(var, OrderKind.DESC)));
+                        break;
+                    }
+                    default: {
+                        throw new NotImplementedException();
+                    }
+                }
+            } else {
+                throw new IllegalStateException();
+            }
+        }
+
+        int n = orderProps.size();
+        sortColumns = new OrderColumn[n];
+        int i = 0;
+        for (ILocalStructuralProperty prop : orderProps) {
+            sortColumns[i++] = ((LocalOrderProperty) prop).getOrderColumn();
+        }
+    }
+
+    public List<ILocalStructuralProperty> getOrderProperties() {
+        return orderProps;
+    }
+
+    @Override
+    public String toString() {
+        if (orderProps == null) {
+            return getOperatorTag().toString();
+        } else {
+            return getOperatorTag().toString() + " " + orderProps;
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AggregatePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AggregatePOperator.java
new file mode 100644
index 0000000..81dc2c2
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AggregatePOperator.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AggregateFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.aggreg.AggregateRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class AggregatePOperator extends AbstractPhysicalOperator {
+
+    public AggregatePOperator() {
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.AGGREGATE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector childProps = op2.getDeliveredPhysicalProperties();
+        deliveredProperties = new StructuralPropertiesVector(childProps.getPartitioningProperty(),
+                new ArrayList<ILocalStructuralProperty>(0));
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        AggregateOperator aggOp = (AggregateOperator) op;
+        if (aggOp.getExecutionMode() == ExecutionMode.PARTITIONED && aggOp.getPartitioningVariable() != null) {
+            StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+            Set<LogicalVariable> partitioningVariables = new ListSet<LogicalVariable>();
+            partitioningVariables.add(aggOp.getPartitioningVariable());
+            pv[0] = new StructuralPropertiesVector(new UnorderedPartitionedProperty(partitioningVariables, null), null);
+            return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+        } else {
+            return emptyUnaryRequirements();
+        }
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        AggregateOperator aggOp = (AggregateOperator) op;
+        List<LogicalVariable> variables = aggOp.getVariables();
+        List<Mutable<ILogicalExpression>> expressions = aggOp.getExpressions();
+        int[] outColumns = new int[variables.size()];
+        for (int i = 0; i < outColumns.length; i++) {
+            outColumns[i] = opSchema.findVariable(variables.get(i));
+        }
+        IAggregateEvaluatorFactory[] aggFactories = new IAggregateEvaluatorFactory[expressions.size()];
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        for (int i = 0; i < aggFactories.length; i++) {
+            AggregateFunctionCallExpression aggFun = (AggregateFunctionCallExpression) expressions.get(i).getValue();
+            aggFactories[i] = expressionRuntimeProvider.createAggregateFunctionFactory(aggFun,
+                    context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas, context);
+        }
+
+        AggregateRuntimeFactory runtime = new AggregateRuntimeFactory(aggFactories);
+
+        // contribute one Asterix framewriter
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(aggOp, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = aggOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, aggOp, 0);
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AssignPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AssignPOperator.java
new file mode 100644
index 0000000..f5bd9d9
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/AssignPOperator.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.AssignRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class AssignPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.ASSIGN;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        AssignOperator assign = (AssignOperator) op;
+        List<LogicalVariable> variables = assign.getVariables();
+        List<Mutable<ILogicalExpression>> expressions = assign.getExpressions();
+        int[] outColumns = new int[variables.size()];
+        for (int i = 0; i < outColumns.length; i++) {
+            outColumns[i] = opSchema.findVariable(variables.get(i));
+        }
+        IScalarEvaluatorFactory[] evalFactories = new IScalarEvaluatorFactory[expressions.size()];
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        for (int i = 0; i < evalFactories.length; i++) {
+            evalFactories[i] = expressionRuntimeProvider.createEvaluatorFactory(expressions.get(i).getValue(),
+                    context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas, context);
+        }
+
+        // TODO push projections into the operator
+        int[] projectionList = JobGenHelper.projectAllVariables(opSchema);
+
+        AssignRuntimeFactory runtime = new AssignRuntimeFactory(outColumns, evalFactories, projectionList);
+
+        // contribute one Asterix framewriter
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(assign, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = assign.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, assign, 0);
+
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/BroadcastPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/BroadcastPOperator.java
new file mode 100644
index 0000000..bf19342
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/BroadcastPOperator.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.BroadcastPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.INodeDomain;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNReplicatingConnectorDescriptor;
+
+public class BroadcastPOperator extends AbstractExchangePOperator {
+
+    private INodeDomain domain;
+
+    public BroadcastPOperator(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.BROADCAST_EXCHANGE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPartitioningProperty pp = new BroadcastPartitioningProperty(domain);
+        this.deliveredProperties = new StructuralPropertiesVector(pp, op2.getDeliveredPhysicalProperties()
+                .getLocalProperties());
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
+        IConnectorDescriptor conn = new MToNReplicatingConnectorDescriptor(spec);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, null);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DataSourceScanPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DataSourceScanPOperator.java
new file mode 100644
index 0000000..a2dac3f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DataSourceScanPOperator.java
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSourcePropertiesProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+
+@SuppressWarnings("rawtypes")
+public class DataSourceScanPOperator extends AbstractScanPOperator {
+
+    private IDataSource<?> dataSource;
+
+    public DataSourceScanPOperator(IDataSource<?> dataSource) {
+        this.dataSource = dataSource;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.DATASOURCE_SCAN;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        // partitioning properties
+        DataSourceScanOperator dssOp = (DataSourceScanOperator) op;
+        IDataSourcePropertiesProvider dspp = dataSource.getPropertiesProvider();
+        deliveredProperties = dspp.computePropertiesVector(dssOp.getVariables());
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        DataSourceScanOperator scan = (DataSourceScanOperator) op;
+        IMetadataProvider mp = context.getMetadataProvider();
+        IVariableTypeEnvironment typeEnv = context.getTypeEnvironment(op);
+        List<LogicalVariable> vars = scan.getVariables();
+        List<LogicalVariable> projectVars = scan.getProjectVariables();
+        Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> p = mp.getScannerRuntime(dataSource, vars,
+                projectVars, scan.isProjectPushed(), opSchema, typeEnv, context, builder.getJobSpec());
+        builder.contributeHyracksOperator(scan, p.first);
+        if (p.second != null) {
+            builder.contributeAlgebricksPartitionConstraint(p.first, p.second);
+        }
+
+        ILogicalOperator srcExchange = scan.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(srcExchange, 0, scan, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/EmptyTupleSourcePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/EmptyTupleSourcePOperator.java
new file mode 100644
index 0000000..bf42c30
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/EmptyTupleSourcePOperator.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.LinkedList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.EmptyTupleSourceRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class EmptyTupleSourcePOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.EMPTY_TUPLE_SOURCE;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        deliveredProperties = new StructuralPropertiesVector(IPartitioningProperty.UNPARTITIONED,
+                new LinkedList<ILocalStructuralProperty>());
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return null;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        EmptyTupleSourceRuntimeFactory runtime = new EmptyTupleSourceRuntimeFactory();
+        RecordDescriptor recDesc = new RecordDescriptor(new ISerializerDeserializer[] {});
+        builder.contributeMicroOperator(op, runtime, recDesc);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ExternalGroupByPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ExternalGroupByPOperator.java
new file mode 100644
index 0000000..55add37
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ExternalGroupByPOperator.java
@@ -0,0 +1,245 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AggregateFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IPartialAggregationTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalGroupingProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.OperatorSchemaImpl;
+import edu.uci.ics.hyracks.algebricks.runtime.base.ICopySerializableAggregateFunctionFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.aggreg.SerializableAggregatorDescriptorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.common.data.partition.FieldHashPartitionComputerFactory;
+import edu.uci.ics.hyracks.dataflow.std.group.HashSpillableTableFactory;
+import edu.uci.ics.hyracks.dataflow.std.group.IAggregatorDescriptorFactory;
+import edu.uci.ics.hyracks.dataflow.std.group.external.ExternalGroupOperatorDescriptor;
+
+public class ExternalGroupByPOperator extends AbstractPhysicalOperator {
+
+    private int tableSize = 0;
+    private int frameLimit = 0;
+    private List<LogicalVariable> columnSet = new ArrayList<LogicalVariable>();
+
+    public ExternalGroupByPOperator(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> gbyList, int frameLimit,
+            int tableSize) {
+        this.tableSize = tableSize;
+        this.frameLimit = frameLimit;
+        computeColumnSet(gbyList);
+    }
+
+    public void computeColumnSet(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> gbyList) {
+        columnSet.clear();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gbyList) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) expr;
+                columnSet.add(v.getVariableReference());
+            }
+        }
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.EXTERNAL_GROUP_BY;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + columnSet;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    public List<LogicalVariable> getGbyColumns() {
+        return columnSet;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        List<ILocalStructuralProperty> propsLocal = new LinkedList<ILocalStructuralProperty>();
+
+        GroupByOperator gOp = (GroupByOperator) op;
+        Set<LogicalVariable> columnSet = new ListSet<LogicalVariable>();
+
+        if (!columnSet.isEmpty()) {
+            propsLocal.add(new LocalGroupingProperty(columnSet));
+        }
+        for (ILogicalPlan p : gOp.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                ILogicalOperator rOp = r.getValue();
+                propsLocal.addAll(rOp.getDeliveredPhysicalProperties().getLocalProperties());
+            }
+        }
+
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector childProp = op2.getDeliveredPhysicalProperties();
+        deliveredProperties = new StructuralPropertiesVector(childProp.getPartitioningProperty(), propsLocal);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) op;
+        if (aop.getExecutionMode() == ExecutionMode.PARTITIONED) {
+            StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+            pv[0] = new StructuralPropertiesVector(new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(
+                    columnSet), null), null);
+            return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+        } else {
+            return emptyUnaryRequirements();
+        }
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        List<LogicalVariable> gbyCols = getGbyColumns();
+        int keys[] = JobGenHelper.variablesToFieldIndexes(gbyCols, inputSchemas[0]);
+        GroupByOperator gby = (GroupByOperator) op;
+        int numFds = gby.getDecorList().size();
+        int fdColumns[] = new int[numFds];
+        int j = 0;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new AlgebricksException("pre-sorted group-by expects variable references.");
+            }
+            VariableReferenceExpression v = (VariableReferenceExpression) expr;
+            LogicalVariable decor = v.getVariableReference();
+            fdColumns[j++] = inputSchemas[0].findVariable(decor);
+        }
+
+        if (gby.getNestedPlans().size() != 1) {
+            throw new AlgebricksException(
+                    "External group-by currently works only for one nested plan with one root containing"
+                            + "an aggregate and a nested-tuple-source.");
+        }
+        ILogicalPlan p0 = gby.getNestedPlans().get(0);
+        if (p0.getRoots().size() != 1) {
+            throw new AlgebricksException(
+                    "External group-by currently works only for one nested plan with one root containing"
+                            + "an aggregate and a nested-tuple-source.");
+        }
+        Mutable<ILogicalOperator> r0 = p0.getRoots().get(0);
+        AggregateOperator aggOp = (AggregateOperator) r0.getValue();
+
+        IPartialAggregationTypeComputer partialAggregationTypeComputer = context.getPartialAggregationTypeComputer();
+        List<Object> intermediateTypes = new ArrayList<Object>();
+        int n = aggOp.getExpressions().size();
+        ICopySerializableAggregateFunctionFactory[] aff = new ICopySerializableAggregateFunctionFactory[n];
+        int i = 0;
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        IVariableTypeEnvironment aggOpInputEnv = context.getTypeEnvironment(aggOp.getInputs().get(0).getValue());
+        IVariableTypeEnvironment outputEnv = context.getTypeEnvironment(op);
+        for (Mutable<ILogicalExpression> exprRef : aggOp.getExpressions()) {
+            AggregateFunctionCallExpression aggFun = (AggregateFunctionCallExpression) exprRef.getValue();
+            aff[i++] = expressionRuntimeProvider.createSerializableAggregateFunctionFactory(aggFun, aggOpInputEnv,
+                    inputSchemas, context);
+            intermediateTypes.add(partialAggregationTypeComputer.getType(aggFun, aggOpInputEnv,
+                    context.getMetadataProvider()));
+        }
+
+        int[] keyAndDecFields = new int[keys.length + fdColumns.length];
+        for (i = 0; i < keys.length; ++i) {
+            keyAndDecFields[i] = keys[i];
+        }
+        for (i = 0; i < fdColumns.length; i++) {
+            keyAndDecFields[keys.length + i] = fdColumns[i];
+        }
+
+        List<LogicalVariable> keyAndDecVariables = new ArrayList<LogicalVariable>();
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getGroupByList())
+            keyAndDecVariables.add(p.first);
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList())
+            keyAndDecVariables.add(GroupByOperator.getDecorVariable(p));
+
+        for (LogicalVariable var : keyAndDecVariables)
+            aggOpInputEnv.setVarType(var, outputEnv.getVarType(var));
+
+        compileSubplans(inputSchemas[0], gby, opSchema, context);
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        IBinaryComparatorFactory[] comparatorFactories = JobGenHelper.variablesToAscBinaryComparatorFactories(gbyCols,
+                aggOpInputEnv, context);
+        RecordDescriptor recordDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        IBinaryHashFunctionFactory[] hashFunctionFactories = JobGenHelper.variablesToBinaryHashFunctionFactories(
+                gbyCols, aggOpInputEnv, context);
+
+        ICopySerializableAggregateFunctionFactory[] merges = new ICopySerializableAggregateFunctionFactory[n];
+        List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>();
+        IOperatorSchema[] localInputSchemas = new IOperatorSchema[1];
+        localInputSchemas[0] = new OperatorSchemaImpl();
+        for (i = 0; i < n; i++) {
+            AggregateFunctionCallExpression aggFun = (AggregateFunctionCallExpression) aggOp.getMergeExpressions()
+                    .get(i).getValue();
+            aggFun.getUsedVariables(usedVars);
+        }
+        i = 0;
+        for (Object type : intermediateTypes) {
+            aggOpInputEnv.setVarType(usedVars.get(i++), type);
+        }
+        for (LogicalVariable keyVar : keyAndDecVariables)
+            localInputSchemas[0].addVariable(keyVar);
+        for (LogicalVariable usedVar : usedVars)
+            localInputSchemas[0].addVariable(usedVar);
+        for (i = 0; i < n; i++) {
+            AggregateFunctionCallExpression mergeFun = (AggregateFunctionCallExpression) aggOp.getMergeExpressions()
+                    .get(i).getValue();
+            merges[i] = expressionRuntimeProvider.createSerializableAggregateFunctionFactory(mergeFun, aggOpInputEnv,
+                    localInputSchemas, context);
+        }
+        IAggregatorDescriptorFactory aggregatorFactory = new SerializableAggregatorDescriptorFactory(aff);
+        IAggregatorDescriptorFactory mergeFactory = new SerializableAggregatorDescriptorFactory(merges);
+
+        ITuplePartitionComputerFactory tpcf = new FieldHashPartitionComputerFactory(keys, hashFunctionFactories);
+        INormalizedKeyComputerFactory normalizedKeyFactory = JobGenHelper.variablesToAscNormalizedKeyComputerFactory(
+                gbyCols, aggOpInputEnv, context);
+        ExternalGroupOperatorDescriptor gbyOpDesc = new ExternalGroupOperatorDescriptor(spec, keyAndDecFields,
+                frameLimit, comparatorFactories, normalizedKeyFactory, aggregatorFactory, mergeFactory,
+                recordDescriptor, new HashSpillableTableFactory(tpcf, tableSize), false);
+
+        contributeOpDesc(builder, gby, gbyOpDesc);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionExchangePOperator.java
new file mode 100644
index 0000000..043cb81
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionExchangePOperator.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.INodeDomain;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputerFactory;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.common.data.partition.FieldHashPartitionComputerFactory;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNPartitioningConnectorDescriptor;
+
+public class HashPartitionExchangePOperator extends AbstractExchangePOperator {
+
+    private List<LogicalVariable> hashFields;
+    private INodeDomain domain;
+
+    public HashPartitionExchangePOperator(List<LogicalVariable> hashFields, INodeDomain domain) {
+        this.hashFields = hashFields;
+        this.domain = domain;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.HASH_PARTITION_EXCHANGE;
+    }
+
+    public List<LogicalVariable> getHashFields() {
+        return hashFields;
+    }
+
+    public INodeDomain getDomain() {
+        return domain;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        IPartitioningProperty p = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(hashFields), domain);
+        this.deliveredProperties = new StructuralPropertiesVector(p, null);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + " " + hashFields;
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
+        int[] keys = new int[hashFields.size()];
+        IBinaryHashFunctionFactory[] hashFunctionFactories = new IBinaryHashFunctionFactory[hashFields.size()];
+        int i = 0;
+        IBinaryHashFunctionFactoryProvider hashFunProvider = context.getBinaryHashFunctionFactoryProvider();
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        for (LogicalVariable v : hashFields) {
+            keys[i] = opSchema.findVariable(v);
+            hashFunctionFactories[i] = hashFunProvider.getBinaryHashFunctionFactory(env.getVarType(v));
+            ++i;
+        }
+        ITuplePartitionComputerFactory tpcf = new FieldHashPartitionComputerFactory(keys, hashFunctionFactories);
+        IConnectorDescriptor conn = new MToNPartitioningConnectorDescriptor(spec, tpcf);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, null);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java
new file mode 100644
index 0000000..f3c9e5a
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java
@@ -0,0 +1,162 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.INodeDomain;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputerFactory;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.common.data.partition.FieldHashPartitionComputerFactory;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNPartitioningMergingConnectorDescriptor;
+
+public class HashPartitionMergeExchangePOperator extends AbstractExchangePOperator {
+
+    private List<OrderColumn> orderColumns;
+    private List<LogicalVariable> partitionFields;
+    private INodeDomain domain;
+
+    public HashPartitionMergeExchangePOperator(List<OrderColumn> orderColumns, List<LogicalVariable> partitionFields,
+            INodeDomain domain) {
+        this.orderColumns = orderColumns;
+        this.partitionFields = partitionFields;
+        this.domain = domain;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.HASH_PARTITION_MERGE_EXCHANGE;
+    }
+
+    public List<OrderColumn> getOrderExpressions() {
+        return orderColumns;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        IPartitioningProperty p = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(partitionFields),
+                domain);
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        List<ILocalStructuralProperty> op2Locals = op2.getDeliveredPhysicalProperties().getLocalProperties();
+        List<ILocalStructuralProperty> locals = new ArrayList<ILocalStructuralProperty>();
+        for (ILocalStructuralProperty prop : op2Locals) {
+            if (prop.getPropertyType() == PropertyType.LOCAL_ORDER_PROPERTY) {
+                locals.add(prop);
+            } else {
+                break;
+            }
+        }
+
+        this.deliveredProperties = new StructuralPropertiesVector(p, locals);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        List<ILocalStructuralProperty> orderProps = new LinkedList<ILocalStructuralProperty>();
+        for (OrderColumn oc : orderColumns) {
+            LogicalVariable var = oc.getColumn();
+            switch (oc.getOrder()) {
+                case ASC: {
+                    orderProps.add(new LocalOrderProperty(new OrderColumn(var, OrderKind.ASC)));
+                    break;
+                }
+                case DESC: {
+                    orderProps.add(new LocalOrderProperty(new OrderColumn(var, OrderKind.DESC)));
+                    break;
+                }
+                default: {
+                    throw new IllegalStateException();
+                }
+            }
+        }
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(null,
+                orderProps) };
+        return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + " MERGE:" + orderColumns + " HASH:" + partitionFields;
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
+        int[] keys = new int[partitionFields.size()];
+        IBinaryHashFunctionFactory[] hashFunctionFactories = new IBinaryHashFunctionFactory[partitionFields.size()];
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        {
+            int i = 0;
+            IBinaryHashFunctionFactoryProvider hashFunProvider = context.getBinaryHashFunctionFactoryProvider();
+            for (LogicalVariable v : partitionFields) {
+                keys[i] = opSchema.findVariable(v);
+                hashFunctionFactories[i] = hashFunProvider.getBinaryHashFunctionFactory(env.getVarType(v));
+                ++i;
+            }
+        }
+        ITuplePartitionComputerFactory tpcf = new FieldHashPartitionComputerFactory(keys, hashFunctionFactories);
+
+        int n = orderColumns.size();
+        int[] sortFields = new int[n];
+        IBinaryComparatorFactory[] comparatorFactories = new IBinaryComparatorFactory[n];
+        {
+            int j = 0;
+            for (OrderColumn oc : orderColumns) {
+                LogicalVariable var = oc.getColumn();
+                sortFields[j] = opSchema.findVariable(var);
+                Object type = env.getVarType(var);
+                IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+                comparatorFactories[j] = bcfp.getBinaryComparatorFactory(type, oc.getOrder() == OrderKind.ASC);
+                j++;
+            }
+        }
+
+        IConnectorDescriptor conn = new MToNPartitioningMergingConnectorDescriptor(spec, tpcf, sortFields,
+                comparatorFactories);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, null);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
new file mode 100644
index 0000000..c737cc4
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
@@ -0,0 +1,142 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator.JoinKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INullWriterFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.join.HybridHashJoinOperatorDescriptor;
+
+public class HybridHashJoinPOperator extends AbstractHashJoinPOperator {
+
+    private final int memSizeInFrames;
+    private final int maxInputBuildSizeInFrames;
+    private final int aveRecordsPerFrame;
+    private final double fudgeFactor;
+
+    public HybridHashJoinPOperator(JoinKind kind, JoinPartitioningType partitioningType,
+            List<LogicalVariable> sideLeftOfEqualities, List<LogicalVariable> sideRightOfEqualities,
+            int memSizeInFrames, int maxInputSize0InFrames, int aveRecordsPerFrame, double fudgeFactor) {
+        super(kind, partitioningType, sideLeftOfEqualities, sideRightOfEqualities);
+        this.memSizeInFrames = memSizeInFrames;
+        this.maxInputBuildSizeInFrames = maxInputSize0InFrames;
+        this.aveRecordsPerFrame = aveRecordsPerFrame;
+        this.fudgeFactor = fudgeFactor;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.HYBRID_HASH_JOIN;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    public double getFudgeFactor() {
+        return fudgeFactor;
+    }
+
+    public int getMemSizeInFrames() {
+        return memSizeInFrames;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + " " + keysLeftBranch + keysRightBranch;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        int[] keysLeft = JobGenHelper.variablesToFieldIndexes(keysLeftBranch, inputSchemas[0]);
+        int[] keysRight = JobGenHelper.variablesToFieldIndexes(keysRightBranch, inputSchemas[1]);
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        IBinaryHashFunctionFactory[] hashFunFactories = JobGenHelper.variablesToBinaryHashFunctionFactories(
+                keysLeftBranch, env, context);
+        IBinaryComparatorFactory[] comparatorFactories = new IBinaryComparatorFactory[keysLeft.length];
+        int i = 0;
+        IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+        for (LogicalVariable v : keysLeftBranch) {
+            Object t = env.getVarType(v);
+            comparatorFactories[i++] = bcfp.getBinaryComparatorFactory(t, true);
+        }
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        IOperatorDescriptor opDesc = null;
+        try {
+            switch (kind) {
+                case INNER: {
+                    opDesc = new HybridHashJoinOperatorDescriptor(spec, getMemSizeInFrames(),
+                            maxInputBuildSizeInFrames, aveRecordsPerFrame, getFudgeFactor(), keysLeft, keysRight,
+                            hashFunFactories, comparatorFactories, recDescriptor);
+                    break;
+                }
+                case LEFT_OUTER: {
+                    INullWriterFactory[] nullWriterFactories = new INullWriterFactory[inputSchemas[1].getSize()];
+                    for (int j = 0; j < nullWriterFactories.length; j++) {
+                        nullWriterFactories[j] = context.getNullWriterFactory();
+                    }
+                    opDesc = new HybridHashJoinOperatorDescriptor(spec, getMemSizeInFrames(),
+                            maxInputBuildSizeInFrames, aveRecordsPerFrame, getFudgeFactor(), keysLeft, keysRight,
+                            hashFunFactories, comparatorFactories, recDescriptor, true, nullWriterFactories);
+                    break;
+                }
+                default: {
+                    throw new NotImplementedException();
+                }
+            }
+        } catch (HyracksDataException e) {
+            throw new AlgebricksException(e);
+        }
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+
+        ILogicalOperator src1 = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src1, 0, op, 0);
+        ILogicalOperator src2 = op.getInputs().get(1).getValue();
+        builder.contributeGraphEdge(src2, 0, op, 1);
+    }
+
+    @Override
+    protected List<ILocalStructuralProperty> deliveredLocalProperties(ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        return new LinkedList<ILocalStructuralProperty>();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java
new file mode 100644
index 0000000..563fcc5
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryHashJoinPOperator.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator.JoinKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INullWriterFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.join.InMemoryHashJoinOperatorDescriptor;
+
+public class InMemoryHashJoinPOperator extends AbstractHashJoinPOperator {
+
+    private final int tableSize;
+
+    /**
+     * builds on the first operator and probes on the second.
+     */
+
+    public InMemoryHashJoinPOperator(JoinKind kind, JoinPartitioningType partitioningType,
+            List<LogicalVariable> sideLeftOfEqualities, List<LogicalVariable> sideRightOfEqualities, int tableSize) {
+        super(kind, partitioningType, sideLeftOfEqualities, sideRightOfEqualities);
+        this.tableSize = tableSize;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.IN_MEMORY_HASH_JOIN;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + " " + keysLeftBranch + keysRightBranch;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        int[] keysLeft = JobGenHelper.variablesToFieldIndexes(keysLeftBranch, inputSchemas[0]);
+        int[] keysRight = JobGenHelper.variablesToFieldIndexes(keysRightBranch, inputSchemas[1]);
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        IBinaryHashFunctionFactory[] hashFunFactories = JobGenHelper.variablesToBinaryHashFunctionFactories(
+                keysLeftBranch, env, context);
+        IBinaryComparatorFactory[] comparatorFactories = new IBinaryComparatorFactory[keysLeft.length];
+        int i = 0;
+        IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+        for (LogicalVariable v : keysLeftBranch) {
+            Object t = env.getVarType(v);
+            comparatorFactories[i++] = bcfp.getBinaryComparatorFactory(t, true);
+        }
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        IOperatorDescriptor opDesc = null;
+
+        switch (kind) {
+            case INNER: {
+                opDesc = new InMemoryHashJoinOperatorDescriptor(spec, keysLeft, keysRight, hashFunFactories,
+                        comparatorFactories, recDescriptor, tableSize);
+                break;
+            }
+            case LEFT_OUTER: {
+                INullWriterFactory[] nullWriterFactories = new INullWriterFactory[inputSchemas[1].getSize()];
+                for (int j = 0; j < nullWriterFactories.length; j++) {
+                    nullWriterFactories[j] = context.getNullWriterFactory();
+                }
+                opDesc = new InMemoryHashJoinOperatorDescriptor(spec, keysLeft, keysRight, hashFunFactories,
+                        comparatorFactories, recDescriptor, true, nullWriterFactories, tableSize);
+                break;
+            }
+            default: {
+                throw new NotImplementedException();
+            }
+        }
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+
+        ILogicalOperator src1 = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src1, 0, op, 0);
+        ILogicalOperator src2 = op.getInputs().get(1).getValue();
+        builder.contributeGraphEdge(src2, 0, op, 1);
+    }
+
+    @Override
+    protected List<ILocalStructuralProperty> deliveredLocalProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op0 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector pv0 = op0.getPhysicalOperator().getDeliveredProperties();
+        List<ILocalStructuralProperty> lp0 = pv0.getLocalProperties();
+        if (lp0 != null) {
+            // maintains the local properties on the probe side
+            return new LinkedList<ILocalStructuralProperty>(lp0);
+        }
+        return new LinkedList<ILocalStructuralProperty>();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryStableSortPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryStableSortPOperator.java
new file mode 100644
index 0000000..ec2862e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InMemoryStableSortPOperator.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IPushRuntimeFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.sort.InMemorySortRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class InMemoryStableSortPOperator extends AbstractStableSortPOperator {
+
+    public InMemoryStableSortPOperator() {
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.IN_MEMORY_STABLE_SORT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        int n = sortColumns.length;
+        int[] sortFields = new int[n];
+        IBinaryComparatorFactory[] comps = new IBinaryComparatorFactory[n];
+        int i = 0;
+        INormalizedKeyComputerFactoryProvider nkcfProvider = context.getNormalizedKeyComputerFactoryProvider();
+        INormalizedKeyComputerFactory nkcf = null;
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        for (OrderColumn oc : sortColumns) {
+            LogicalVariable var = oc.getColumn();
+            sortFields[i] = opSchema.findVariable(var);
+            Object type = env.getVarType(var);
+            OrderKind order = oc.getOrder();
+            if (i == 0 && nkcfProvider != null && type != null) {
+                nkcf = nkcfProvider.getNormalizedKeyComputerFactory(type, order == OrderKind.ASC);
+            }
+
+            IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+            comps[i] = bcfp.getBinaryComparatorFactory(type, oc.getOrder() == OrderKind.ASC);
+            i++;
+        }
+
+        IPushRuntimeFactory runtime = new InMemorySortRuntimeFactory(sortFields, nkcf, comps, null);
+        builder.contributeMicroOperator(op, runtime, recDescriptor);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/IndexInsertDeletePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/IndexInsertDeletePOperator.java
new file mode 100644
index 0000000..e000b85
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/IndexInsertDeletePOperator.java
@@ -0,0 +1,119 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSourceIndex;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator.Kind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public class IndexInsertDeletePOperator extends AbstractPhysicalOperator {
+
+    private final List<LogicalVariable> primaryKeys;
+    private final List<LogicalVariable> secondaryKeys;
+    private final ILogicalExpression filterExpr;
+    private final IDataSourceIndex<?, ?> dataSourceIndex;
+
+    public IndexInsertDeletePOperator(List<LogicalVariable> primaryKeys, List<LogicalVariable> secondaryKeys,
+    		Mutable<ILogicalExpression> filterExpr, IDataSourceIndex<?, ?> dataSourceIndex) {
+        this.primaryKeys = primaryKeys;
+        this.secondaryKeys = secondaryKeys;
+        if (filterExpr != null) {
+        	this.filterExpr = filterExpr.getValue();
+        } else {
+        	this.filterExpr = null;
+        }
+        this.dataSourceIndex = dataSourceIndex;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.INDEX_INSERT_DELETE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();        
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        List<LogicalVariable> scanVariables = new ArrayList<LogicalVariable>();
+        scanVariables.addAll(primaryKeys);
+        scanVariables.add(new LogicalVariable(-1));
+        IPartitioningProperty pp = dataSourceIndex.getDataSource().getPropertiesProvider()
+                .computePropertiesVector(scanVariables).getPartitioningProperty();
+        List<ILocalStructuralProperty> orderProps = new LinkedList<ILocalStructuralProperty>();
+        for (LogicalVariable k : secondaryKeys) {
+            orderProps.add(new LocalOrderProperty(new OrderColumn(k, OrderKind.ASC)));
+        }
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(pp,
+                orderProps) };
+        return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @SuppressWarnings({ "rawtypes", "unchecked" })
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        IndexInsertDeleteOperator insertDeleteOp = (IndexInsertDeleteOperator) op;
+        IMetadataProvider mp = context.getMetadataProvider();
+
+        JobSpecification spec = builder.getJobSpec();
+        RecordDescriptor inputDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas[0],
+                context);
+
+        Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> runtimeAndConstraints = null;
+        IVariableTypeEnvironment typeEnv = context.getTypeEnvironment(insertDeleteOp);
+        if (insertDeleteOp.getOperation() == Kind.INSERT) {
+            runtimeAndConstraints = mp.getIndexInsertRuntime(dataSourceIndex, propagatedSchema, inputSchemas, typeEnv,
+                    primaryKeys, secondaryKeys, filterExpr, inputDesc, context, spec);
+        } else {
+            runtimeAndConstraints = mp.getIndexDeleteRuntime(dataSourceIndex, propagatedSchema, inputSchemas, typeEnv,
+                    primaryKeys, secondaryKeys, filterExpr, inputDesc, context, spec);
+        }
+        builder.contributeHyracksOperator(insertDeleteOp, runtimeAndConstraints.first);
+        builder.contributeAlgebricksPartitionConstraint(runtimeAndConstraints.first, runtimeAndConstraints.second);
+        ILogicalOperator src = insertDeleteOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, insertDeleteOp, 0);
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InsertDeletePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InsertDeletePOperator.java
new file mode 100644
index 0000000..477d257
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/InsertDeletePOperator.java
@@ -0,0 +1,96 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator.Kind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+@SuppressWarnings("rawtypes")
+public class InsertDeletePOperator extends AbstractPhysicalOperator {
+
+    private LogicalVariable payload;
+    private List<LogicalVariable> keys;
+    private IDataSource<?> dataSource;
+
+    public InsertDeletePOperator(LogicalVariable payload, List<LogicalVariable> keys, IDataSource dataSource) {
+        this.payload = payload;
+        this.keys = keys;
+        this.dataSource = dataSource;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.INSERT_DELETE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        List<LogicalVariable> scanVariables = new ArrayList<LogicalVariable>();
+        scanVariables.addAll(keys);
+        scanVariables.add(new LogicalVariable(-1));
+        IPhysicalPropertiesVector r = dataSource.getPropertiesProvider().computePropertiesVector(scanVariables);
+        IPhysicalPropertiesVector[] requirements = new IPhysicalPropertiesVector[1];
+        requirements[0] = r;
+        return new PhysicalRequirements(requirements, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @SuppressWarnings("unchecked")
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        InsertDeleteOperator insertDeleteOp = (InsertDeleteOperator) op;
+        IMetadataProvider mp = context.getMetadataProvider();
+        JobSpecification spec = builder.getJobSpec();
+        RecordDescriptor inputDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas[0],
+                context);
+
+        Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> runtimeAndConstraints = null;
+        if (insertDeleteOp.getOperation() == Kind.INSERT)
+            runtimeAndConstraints = mp.getInsertRuntime(dataSource, propagatedSchema, keys, payload, inputDesc,
+                    context, spec);
+        else
+            runtimeAndConstraints = mp.getDeleteRuntime(dataSource, propagatedSchema, keys, payload, inputDesc,
+                    context, spec);
+
+        builder.contributeHyracksOperator(insertDeleteOp, runtimeAndConstraints.first);
+        builder.contributeAlgebricksPartitionConstraint(runtimeAndConstraints.first, runtimeAndConstraints.second);
+        ILogicalOperator src = insertDeleteOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, insertDeleteOp, 0);
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java
new file mode 100644
index 0000000..c159ffd
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/MicroPreclusteredGroupByPOperator.java
@@ -0,0 +1,80 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.AlgebricksPipeline;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.aggreg.NestedPlansAccumulatingAggregatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.group.MicroPreClusteredGroupRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.dataflow.std.group.IAggregatorDescriptorFactory;
+
+public class MicroPreclusteredGroupByPOperator extends AbstractPreclusteredGroupByPOperator {
+
+    public MicroPreclusteredGroupByPOperator(List<LogicalVariable> columnList) {
+        super(columnList);
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.MICRO_PRE_CLUSTERED_GROUP_BY;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        int keys[] = JobGenHelper.variablesToFieldIndexes(columnList, inputSchemas[0]);
+        GroupByOperator gby = (GroupByOperator) op;
+        int numFds = gby.getDecorList().size();
+        int fdColumns[] = new int[numFds];
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        int j = 0;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new AlgebricksException("pre-sorted group-by expects variable references.");
+            }
+            VariableReferenceExpression v = (VariableReferenceExpression) expr;
+            LogicalVariable decor = v.getVariableReference();
+            fdColumns[j++] = inputSchemas[0].findVariable(decor);
+        }
+        // compile subplans and set the gby op. schema accordingly
+        AlgebricksPipeline[] subplans = compileSubplans(inputSchemas[0], gby, opSchema, context);
+        IAggregatorDescriptorFactory aggregatorFactory = new NestedPlansAccumulatingAggregatorFactory(subplans, keys,
+                fdColumns);
+
+        IBinaryComparatorFactory[] comparatorFactories = JobGenHelper.variablesToAscBinaryComparatorFactories(
+                columnList, env, context);
+        RecordDescriptor recordDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        RecordDescriptor inputRecordDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op.getInputs().get(0).getValue()),
+                inputSchemas[0], context);
+        MicroPreClusteredGroupRuntimeFactory runtime = new MicroPreClusteredGroupRuntimeFactory(keys,
+                comparatorFactories, aggregatorFactory, inputRecordDesc, recordDescriptor, null);
+        builder.contributeMicroOperator(gby, runtime, recordDescriptor);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java
new file mode 100644
index 0000000..8cbd2d8
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java
@@ -0,0 +1,277 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator.JoinKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.BroadcastPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryBooleanInspector;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryBooleanInspectorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.api.comm.IFrameTupleAccessor;
+import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePairComparator;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePairComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.data.std.api.IPointable;
+import edu.uci.ics.hyracks.data.std.primitive.VoidPointable;
+import edu.uci.ics.hyracks.dataflow.common.data.accessors.FrameTupleReference;
+import edu.uci.ics.hyracks.dataflow.common.data.accessors.IFrameTupleReference;
+import edu.uci.ics.hyracks.dataflow.std.join.NestedLoopJoinOperatorDescriptor;
+
+/**
+ * Left input is broadcast and preserves its local properties.
+ * Right input can be partitioned in any way.
+ */
+public class NLJoinPOperator extends AbstractJoinPOperator {
+
+    private final int memSize;
+
+    public NLJoinPOperator(JoinKind kind, JoinPartitioningType partitioningType, int memSize) {
+        super(kind, partitioningType);
+        this.memSize = memSize;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.NESTED_LOOP;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator iop, IOptimizationContext context) {
+        if (partitioningType != JoinPartitioningType.BROADCAST) {
+            throw new NotImplementedException(partitioningType + " nested loop joins are not implemented.");
+        }
+
+        IPartitioningProperty pp;
+
+        AbstractLogicalOperator op = (AbstractLogicalOperator) iop;
+
+        if (op.getExecutionMode() == AbstractLogicalOperator.ExecutionMode.PARTITIONED) {
+            AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(1).getValue();
+            IPhysicalPropertiesVector pv1 = op2.getPhysicalOperator().getDeliveredProperties();
+            if (pv1 == null) {
+                pp = null;
+            } else {
+                pp = pv1.getPartitioningProperty();
+            }
+        } else {
+        	pp = IPartitioningProperty.UNPARTITIONED;
+        }
+
+        List<ILocalStructuralProperty> localProps = new LinkedList<ILocalStructuralProperty>();
+        this.deliveredProperties = new StructuralPropertiesVector(pp, localProps);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        if (partitioningType != JoinPartitioningType.BROADCAST) {
+            throw new NotImplementedException(partitioningType + " nested loop joins are not implemented.");
+        }
+
+        StructuralPropertiesVector[] pv = new StructuralPropertiesVector[2];
+        pv[0] = new StructuralPropertiesVector(new BroadcastPartitioningProperty(null), null);
+        pv[1] = new StructuralPropertiesVector(null, null);
+        return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        AbstractBinaryJoinOperator join = (AbstractBinaryJoinOperator) op;
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        IOperatorSchema[] conditionInputSchemas = new IOperatorSchema[1];
+        conditionInputSchemas[0] = propagatedSchema;
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        IScalarEvaluatorFactory cond = expressionRuntimeProvider.createEvaluatorFactory(join.getCondition().getValue(),
+                context.getTypeEnvironment(op), conditionInputSchemas, context);
+        ITuplePairComparatorFactory comparatorFactory = new TuplePairEvaluatorFactory(cond,
+                context.getBinaryBooleanInspectorFactory());
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        IOperatorDescriptor opDesc = null;
+
+        switch (kind) {
+            case INNER: {
+                opDesc = new NestedLoopJoinOperatorDescriptor(spec, comparatorFactory, recDescriptor, memSize);
+                break;
+            }
+            case LEFT_OUTER:
+            default: {
+                throw new NotImplementedException();
+            }
+        }
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+
+        ILogicalOperator src1 = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src1, 0, op, 0);
+        ILogicalOperator src2 = op.getInputs().get(1).getValue();
+        builder.contributeGraphEdge(src2, 0, op, 1);
+    }
+
+    public static class TuplePairEvaluatorFactory implements ITuplePairComparatorFactory {
+
+        private static final long serialVersionUID = 1L;
+        private final IScalarEvaluatorFactory cond;
+        private final IBinaryBooleanInspectorFactory binaryBooleanInspectorFactory;
+
+        public TuplePairEvaluatorFactory(IScalarEvaluatorFactory cond,
+                IBinaryBooleanInspectorFactory binaryBooleanInspectorFactory) {
+            this.cond = cond;
+            this.binaryBooleanInspectorFactory = binaryBooleanInspectorFactory;
+        }
+
+        @Override
+        public synchronized ITuplePairComparator createTuplePairComparator(IHyracksTaskContext ctx) {
+            return new TuplePairEvaluator(ctx, cond, binaryBooleanInspectorFactory.createBinaryBooleanInspector(ctx));
+        }
+    }
+
+    public static class TuplePairEvaluator implements ITuplePairComparator {
+        private final IHyracksTaskContext ctx;
+        private IScalarEvaluator condEvaluator;
+        private final IScalarEvaluatorFactory condFactory;
+        private final IPointable p;
+        private final CompositeFrameTupleReference compositeTupleRef;
+        private final FrameTupleReference leftRef;
+        private final FrameTupleReference rightRef;
+        private final IBinaryBooleanInspector binaryBooleanInspector;
+
+        public TuplePairEvaluator(IHyracksTaskContext ctx, IScalarEvaluatorFactory condFactory,
+                IBinaryBooleanInspector binaryBooleanInspector) {
+            this.ctx = ctx;
+            this.condFactory = condFactory;
+            this.binaryBooleanInspector = binaryBooleanInspector;
+            this.leftRef = new FrameTupleReference();
+            this.p = VoidPointable.FACTORY.createPointable();
+            this.rightRef = new FrameTupleReference();
+            this.compositeTupleRef = new CompositeFrameTupleReference(leftRef, rightRef);
+        }
+
+        @Override
+        public int compare(IFrameTupleAccessor outerAccessor, int outerIndex, IFrameTupleAccessor innerAccessor,
+                int innerIndex) throws HyracksDataException {
+            if (condEvaluator == null) {
+                try {
+                    this.condEvaluator = condFactory.createScalarEvaluator(ctx);
+                } catch (AlgebricksException ae) {
+                    throw new HyracksDataException(ae);
+                }
+            }
+            compositeTupleRef.reset(outerAccessor, outerIndex, innerAccessor, innerIndex);
+            try {
+                condEvaluator.evaluate(compositeTupleRef, p);
+            } catch (AlgebricksException ae) {
+                throw new HyracksDataException(ae);
+            }
+            boolean result = binaryBooleanInspector
+                    .getBooleanValue(p.getByteArray(), p.getStartOffset(), p.getLength());
+            if (result)
+                return 0;
+            else
+                return 1;
+        }
+    }
+
+    public static class CompositeFrameTupleReference implements IFrameTupleReference {
+
+        private final FrameTupleReference refLeft;
+        private final FrameTupleReference refRight;
+
+        public CompositeFrameTupleReference(FrameTupleReference refLeft, FrameTupleReference refRight) {
+            this.refLeft = refLeft;
+            this.refRight = refRight;
+        }
+
+        public void reset(IFrameTupleAccessor outerAccessor, int outerIndex, IFrameTupleAccessor innerAccessor,
+                int innerIndex) {
+            refLeft.reset(outerAccessor, outerIndex);
+            refRight.reset(innerAccessor, innerIndex);
+        }
+
+        @Override
+        public int getFieldCount() {
+            return refLeft.getFieldCount() + refRight.getFieldCount();
+        }
+
+        @Override
+        public byte[] getFieldData(int fIdx) {
+            int leftFieldCount = refLeft.getFieldCount();
+            if (fIdx < leftFieldCount)
+                return refLeft.getFieldData(fIdx);
+            else
+                return refRight.getFieldData(fIdx - leftFieldCount);
+        }
+
+        @Override
+        public int getFieldStart(int fIdx) {
+            int leftFieldCount = refLeft.getFieldCount();
+            if (fIdx < leftFieldCount)
+                return refLeft.getFieldStart(fIdx);
+            else
+                return refRight.getFieldStart(fIdx - leftFieldCount);
+        }
+
+        @Override
+        public int getFieldLength(int fIdx) {
+            int leftFieldCount = refLeft.getFieldCount();
+            if (fIdx < leftFieldCount)
+                return refLeft.getFieldLength(fIdx);
+            else
+                return refRight.getFieldLength(fIdx - leftFieldCount);
+        }
+
+        @Override
+        public IFrameTupleAccessor getFrameTupleAccessor() {
+            throw new NotImplementedException();
+        }
+
+        @Override
+        public int getTupleIndex() {
+            throw new NotImplementedException();
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NestedTupleSourcePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NestedTupleSourcePOperator.java
new file mode 100644
index 0000000..47a3dd2
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NestedTupleSourcePOperator.java
@@ -0,0 +1,74 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.NestedTupleSourceRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class NestedTupleSourcePOperator extends AbstractPhysicalOperator {
+
+    public NestedTupleSourcePOperator() {
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.NESTED_TUPLE_SOURCE;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        Mutable<ILogicalOperator> dataSource = ((NestedTupleSourceOperator) op).getDataSourceReference();
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) dataSource.getValue().getInputs().get(0).getValue();
+        IPhysicalPropertiesVector inheritedProps = op2.getDeliveredPhysicalProperties();
+        deliveredProperties = (StructuralPropertiesVector) inheritedProps.clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return null;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        propagatedSchema.addAllVariables(outerPlanSchema);
+        NestedTupleSourceRuntimeFactory runtime = new NestedTupleSourceRuntimeFactory();
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        builder.contributeMicroOperator(op, runtime, recDesc);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/OneToOneExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/OneToOneExchangePOperator.java
new file mode 100644
index 0000000..eb4fffa
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/OneToOneExchangePOperator.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.connectors.OneToOneConnectorDescriptor;
+
+public class OneToOneExchangePOperator extends AbstractExchangePOperator {
+
+    public OneToOneExchangePOperator() {
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.ONE_TO_ONE_EXCHANGE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) {
+        IConnectorDescriptor conn = new OneToOneConnectorDescriptor(spec);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, TargetConstraint.SAME_COUNT);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreSortedDistinctByPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreSortedDistinctByPOperator.java
new file mode 100644
index 0000000..29af97c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreSortedDistinctByPOperator.java
@@ -0,0 +1,129 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator.ExecutionMode;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.UnorderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.aggreg.SimpleAlgebricksAccumulatingAggregatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.group.IAggregatorDescriptorFactory;
+import edu.uci.ics.hyracks.dataflow.std.group.preclustered.PreclusteredGroupOperatorDescriptor;
+
+public class PreSortedDistinctByPOperator extends AbstractPhysicalOperator {
+
+    private List<LogicalVariable> columnList;
+
+    public PreSortedDistinctByPOperator(List<LogicalVariable> columnList) {
+        this.columnList = columnList;
+    }
+
+    public void setDistinctByColumns(List<LogicalVariable> distinctByColumns) {
+        this.columnList = distinctByColumns;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPartitioningProperty pp = op2.getDeliveredPhysicalProperties().getPartitioningProperty();
+        List<ILocalStructuralProperty> propsLocal = op2.getDeliveredPhysicalProperties().getLocalProperties();
+        deliveredProperties = new StructuralPropertiesVector(pp, propsLocal);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+        List<ILocalStructuralProperty> localProps = new ArrayList<ILocalStructuralProperty>(columnList.size());
+        for (LogicalVariable column : columnList) {
+            localProps.add(new LocalOrderProperty(new OrderColumn(column, OrderKind.ASC)));
+        }
+        IPartitioningProperty pp = null;
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) op;
+        if (aop.getExecutionMode() == ExecutionMode.PARTITIONED) {
+            pp = new UnorderedPartitionedProperty(new ListSet<LogicalVariable>(columnList), null);
+        }
+        pv[0] = new StructuralPropertiesVector(pp, localProps);
+        return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        int keys[] = JobGenHelper.variablesToFieldIndexes(columnList, inputSchemas[0]);
+        int sz = inputSchemas[0].getSize();
+        int fdSz = sz - columnList.size();
+        int[] fdColumns = new int[fdSz];
+        int j = 0;
+        for (LogicalVariable v : inputSchemas[0]) {
+            if (!columnList.contains(v)) {
+                fdColumns[j++] = inputSchemas[0].findVariable(v);
+            }
+        }
+        IBinaryComparatorFactory[] comparatorFactories = JobGenHelper.variablesToAscBinaryComparatorFactories(
+                columnList, context.getTypeEnvironment(op), context);
+        IAggregateEvaluatorFactory[] aggFactories = new IAggregateEvaluatorFactory[] {};
+        IAggregatorDescriptorFactory aggregatorFactory = new SimpleAlgebricksAccumulatingAggregatorFactory(
+                aggFactories, keys, fdColumns);
+
+        RecordDescriptor recordDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        PreclusteredGroupOperatorDescriptor opDesc = new PreclusteredGroupOperatorDescriptor(spec, keys,
+                comparatorFactories, aggregatorFactory, recordDescriptor);
+
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.PRE_SORTED_DISTINCT_BY;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java
new file mode 100644
index 0000000..0849c7d
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/PreclusteredGroupByPOperator.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.AlgebricksPipeline;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.aggreg.NestedPlansAccumulatingAggregatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.group.IAggregatorDescriptorFactory;
+import edu.uci.ics.hyracks.dataflow.std.group.preclustered.PreclusteredGroupOperatorDescriptor;
+
+public class PreclusteredGroupByPOperator extends AbstractPreclusteredGroupByPOperator {
+
+    public PreclusteredGroupByPOperator(List<LogicalVariable> columnList) {
+        super(columnList);
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.PRE_CLUSTERED_GROUP_BY;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        int keys[] = JobGenHelper.variablesToFieldIndexes(columnList, inputSchemas[0]);
+        GroupByOperator gby = (GroupByOperator) op;
+        int numFds = gby.getDecorList().size();
+        int fdColumns[] = new int[numFds];
+        int j = 0;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : gby.getDecorList()) {
+            ILogicalExpression expr = p.second.getValue();
+            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new AlgebricksException("pre-sorted group-by expects variable references.");
+            }
+            VariableReferenceExpression v = (VariableReferenceExpression) expr;
+            LogicalVariable decor = v.getVariableReference();
+            fdColumns[j++] = inputSchemas[0].findVariable(decor);
+        }
+        // compile subplans and set the gby op. schema accordingly
+        AlgebricksPipeline[] subplans = compileSubplans(inputSchemas[0], gby, opSchema, context);
+        IAggregatorDescriptorFactory aggregatorFactory = new NestedPlansAccumulatingAggregatorFactory(subplans, keys,
+                fdColumns);
+
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        IBinaryComparatorFactory[] comparatorFactories = JobGenHelper.variablesToAscBinaryComparatorFactories(
+                columnList, context.getTypeEnvironment(op), context);
+        RecordDescriptor recordDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+
+        PreclusteredGroupOperatorDescriptor opDesc = new PreclusteredGroupOperatorDescriptor(spec, keys,
+                comparatorFactories, aggregatorFactory, recordDescriptor);
+
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RandomMergeExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RandomMergeExchangePOperator.java
new file mode 100644
index 0000000..22d8cc3
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RandomMergeExchangePOperator.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNReplicatingConnectorDescriptor;
+
+public class RandomMergeExchangePOperator extends AbstractExchangePOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.RANDOM_MERGE_EXCHANGE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        this.deliveredProperties = new StructuralPropertiesVector(IPartitioningProperty.UNPARTITIONED,
+                new ArrayList<ILocalStructuralProperty>(0));
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) {
+        IConnectorDescriptor conn = new MToNReplicatingConnectorDescriptor(spec);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, TargetConstraint.ONE);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java
new file mode 100644
index 0000000..7e3c935
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.INodeDomain;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderedPartitionedProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+
+public class RangePartitionPOperator extends AbstractExchangePOperator {
+
+    private ArrayList<OrderColumn> partitioningFields;
+    private INodeDomain domain;
+
+    public RangePartitionPOperator(ArrayList<OrderColumn> partitioningFields, INodeDomain domain) {
+        this.partitioningFields = partitioningFields;
+        this.domain = domain;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.RANGE_PARTITION_EXCHANGE;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        IPartitioningProperty p = new OrderedPartitionedProperty(partitioningFields, domain);
+        this.deliveredProperties = new StructuralPropertiesVector(p, new LinkedList<ILocalStructuralProperty>());
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
+        throw new NotImplementedException();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ReplicatePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ReplicatePOperator.java
new file mode 100644
index 0000000..060e8d7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/ReplicatePOperator.java
@@ -0,0 +1,73 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.misc.SplitOperatorDescriptor;
+
+public class ReplicatePOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.SPLIT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+
+        ReplicateOperator rop = (ReplicateOperator) op;
+        int outputArity = rop.getOutputArity();
+
+        SplitOperatorDescriptor splitOpDesc = new SplitOperatorDescriptor(spec, recDescriptor, outputArity);
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, splitOpDesc);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RunningAggregatePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RunningAggregatePOperator.java
new file mode 100644
index 0000000..b37c0ea
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RunningAggregatePOperator.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.StatefulFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IRunningAggregateEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.RunningAggregateRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class RunningAggregatePOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.RUNNING_AGGREGATE;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        IPartitioningProperty pp = null;
+        RunningAggregateOperator ragg = (RunningAggregateOperator) op;
+        for (Mutable<ILogicalExpression> exprRef : ragg.getExpressions()) {
+            StatefulFunctionCallExpression f = (StatefulFunctionCallExpression) exprRef.getValue();
+            IPartitioningProperty p = f.getRequiredPartitioningProperty();
+            if (p != null) {
+                if (pp == null) {
+                    pp = p;
+                } else {
+                    throw new IllegalStateException("Two stateful functions want to set partitioning requirements: "
+                            + pp + " and " + p);
+                }
+            }
+        }
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(pp, null) };
+        return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        RunningAggregateOperator ragg = (RunningAggregateOperator) op;
+        List<LogicalVariable> variables = ragg.getVariables();
+        List<Mutable<ILogicalExpression>> expressions = ragg.getExpressions();
+        int[] outColumns = new int[variables.size()];
+        for (int i = 0; i < outColumns.length; i++) {
+            outColumns[i] = opSchema.findVariable(variables.get(i));
+        }
+        IRunningAggregateEvaluatorFactory[] runningAggFuns = new IRunningAggregateEvaluatorFactory[expressions.size()];
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        for (int i = 0; i < runningAggFuns.length; i++) {
+            StatefulFunctionCallExpression expr = (StatefulFunctionCallExpression) expressions.get(i).getValue();
+            runningAggFuns[i] = expressionRuntimeProvider.createRunningAggregateFunctionFactory(expr,
+                    context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas, context);
+        }
+
+        // TODO push projections into the operator
+        int[] projectionList = JobGenHelper.projectAllVariables(opSchema);
+
+        RunningAggregateRuntimeFactory runtime = new RunningAggregateRuntimeFactory(outColumns, runningAggFuns,
+                projectionList);
+
+        // contribute one Asterix framewriter
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(ragg, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = ragg.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, ragg, 0);
+
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkPOperator.java
new file mode 100644
index 0000000..ccb61a2
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkPOperator.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.base.SinkRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class SinkPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.SINK;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        SinkRuntimeFactory runtime = new SinkRuntimeFactory();
+        builder.contributeMicroOperator(op, runtime, recDesc);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkWritePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkWritePOperator.java
new file mode 100644
index 0000000..e89b8e0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SinkWritePOperator.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSink;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IPushRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class SinkWritePOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.SINK_WRITE;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        WriteOperator write = (WriteOperator) op;
+        IDataSink sink = write.getDataSink();
+        IPartitioningProperty pp = sink.getPartitioningProperty();
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(pp, null) };
+        return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        WriteOperator write = (WriteOperator) op;
+        int[] columns = new int[write.getExpressions().size()];
+        int i = 0;
+        for (Mutable<ILogicalExpression> exprRef : write.getExpressions()) {
+            ILogicalExpression expr = exprRef.getValue();
+            if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                throw new NotImplementedException("Only writing variable expressions is supported.");
+            }
+            VariableReferenceExpression varRef = (VariableReferenceExpression) expr;
+            LogicalVariable v = varRef.getVariableReference();
+            columns[i++] = inputSchemas[0].findVariable(v);
+        }
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        RecordDescriptor inputDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas[0],
+                context);
+
+        IPrinterFactory[] pf = JobGenHelper.mkPrinterFactories(inputSchemas[0], context.getTypeEnvironment(op),
+                context, columns);
+
+        IMetadataProvider<?, ?> mp = context.getMetadataProvider();
+
+        Pair<IPushRuntimeFactory, AlgebricksPartitionConstraint> runtime = mp.getWriteFileRuntime(write.getDataSink(),
+                columns, pf, inputDesc);
+
+        builder.contributeMicroOperator(write, runtime.first, recDesc, runtime.second);
+        ILogicalOperator src = write.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, write, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SortMergeExchangePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SortMergeExchangePOperator.java
new file mode 100644
index 0000000..19d6c79
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SortMergeExchangePOperator.java
@@ -0,0 +1,144 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder.TargetConstraint;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.LocalOrderProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ITuplePartitionComputerFactory;
+import edu.uci.ics.hyracks.api.job.IConnectorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.common.data.partition.FieldHashPartitionComputerFactory;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNPartitioningMergingConnectorDescriptor;
+
+public class SortMergeExchangePOperator extends AbstractExchangePOperator {
+
+    private OrderColumn[] sortColumns;
+
+    public SortMergeExchangePOperator(OrderColumn[] sortColumns) {
+        this.sortColumns = sortColumns;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.SORT_MERGE_EXCHANGE;
+    }
+
+    public OrderColumn[] getSortColumns() {
+        return sortColumns;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append(getOperatorTag());
+        sb.append(" [");
+        sb.append(sortColumns[0]);
+        for (int i = 1; i < sortColumns.length; i++) {
+            sb.append(", " + sortColumns[i]);
+        }
+        sb.append(" ]");
+        return sb.toString();
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator inp1 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector pv1 = inp1.getDeliveredPhysicalProperties();
+        if (pv1 == null) {
+            inp1.computeDeliveredPhysicalProperties(context);
+            pv1 = inp1.getDeliveredPhysicalProperties();
+        }
+        int sortCol = 0;
+        List<ILocalStructuralProperty> localProps = new ArrayList<ILocalStructuralProperty>(sortColumns.length);
+        for (ILocalStructuralProperty prop : pv1.getLocalProperties()) {
+            if (prop.getPropertyType() == PropertyType.LOCAL_ORDER_PROPERTY) {
+                LocalOrderProperty lop = (LocalOrderProperty) prop;
+                if (lop.getOrderColumn().equals(sortColumns[sortCol])) {
+                    localProps.add(lop);
+                    sortCol++;
+                    if (sortCol == sortColumns.length) {
+                        break;
+                    }
+                }
+            } else {
+                break;
+            }
+        }
+        if (sortCol < sortColumns.length) {
+            localProps = null;
+        }
+        this.deliveredProperties = new StructuralPropertiesVector(IPartitioningProperty.UNPARTITIONED, localProps);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        List<ILocalStructuralProperty> localProps = new ArrayList<ILocalStructuralProperty>(sortColumns.length);
+        for (OrderColumn oc : sortColumns) {
+            localProps.add(new LocalOrderProperty(oc));
+        }
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(null,
+                localProps) };
+        return new PhysicalRequirements(r, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public Pair<IConnectorDescriptor, TargetConstraint> createConnectorDescriptor(IConnectorDescriptorRegistry spec,
+            ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
+        int n = sortColumns.length;
+        int[] sortFields = new int[n];
+        IBinaryComparatorFactory[] comps = new IBinaryComparatorFactory[n];
+        IBinaryHashFunctionFactory[] hashFuns = new IBinaryHashFunctionFactory[n];
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        for (int i = 0; i < n; i++) {
+            sortFields[i] = opSchema.findVariable(sortColumns[i].getColumn());
+            Object type = env.getVarType(sortColumns[i].getColumn());
+            IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+            comps[i] = bcfp.getBinaryComparatorFactory(type, sortColumns[i].getOrder() == OrderKind.ASC);
+            IBinaryHashFunctionFactoryProvider bhffp = context.getBinaryHashFunctionFactoryProvider();
+            hashFuns[i] = bhffp.getBinaryHashFunctionFactory(type);
+        }
+        ITuplePartitionComputerFactory tpcf = new FieldHashPartitionComputerFactory(sortFields, hashFuns);
+        IConnectorDescriptor conn = new MToNPartitioningMergingConnectorDescriptor(spec, tpcf, sortFields, comps);
+        return new Pair<IConnectorDescriptor, TargetConstraint>(conn, TargetConstraint.ONE);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StableSortPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StableSortPOperator.java
new file mode 100644
index 0000000..df15f29
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StableSortPOperator.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.sort.ExternalSortOperatorDescriptor;
+
+/**
+ * This will always be attached to an {@link OrderOperator} logical operator.
+ */
+
+public class StableSortPOperator extends AbstractStableSortPOperator {
+
+    private int maxNumberOfFrames;
+
+    public StableSortPOperator(int maxNumberOfFrames) {
+        super();
+        this.maxNumberOfFrames = maxNumberOfFrames;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STABLE_SORT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        int n = sortColumns.length;
+        int[] sortFields = new int[n];
+        IBinaryComparatorFactory[] comps = new IBinaryComparatorFactory[n];
+
+        INormalizedKeyComputerFactoryProvider nkcfProvider = context.getNormalizedKeyComputerFactoryProvider();
+        INormalizedKeyComputerFactory nkcf = null;
+
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        int i = 0;
+        for (OrderColumn oc : sortColumns) {
+            LogicalVariable var = oc.getColumn();
+            sortFields[i] = opSchema.findVariable(var);
+            Object type = env.getVarType(var);
+            OrderKind order = oc.getOrder();
+            if (i == 0 && nkcfProvider != null && type != null) {
+                nkcf = nkcfProvider.getNormalizedKeyComputerFactory(type, order == OrderKind.ASC);
+            }
+            IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
+            comps[i] = bcfp.getBinaryComparatorFactory(type, oc.getOrder() == OrderKind.ASC);
+            i++;
+        }
+
+        ExternalSortOperatorDescriptor sortOpDesc = new ExternalSortOperatorDescriptor(spec, maxNumberOfFrames,
+                sortFields, nkcf, comps, recDescriptor);
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, sortOpDesc);
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamDiePOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamDiePOperator.java
new file mode 100644
index 0000000..73b9b79
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamDiePOperator.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.StreamDieRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class StreamDiePOperator extends AbstractPhysicalOperator {
+
+    public StreamDiePOperator() {
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STREAM_DIE;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+        pv[0] = (StructuralPropertiesVector) reqdByParent;
+        return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        DieOperator die = (DieOperator) op;
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        IScalarEvaluatorFactory afterObjectsFact = expressionRuntimeProvider.createEvaluatorFactory(die
+                .getAfterObjects().getValue(), env, inputSchemas, context);
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        StreamDieRuntimeFactory runtime = new StreamDieRuntimeFactory(afterObjectsFact, null,
+                context.getBinaryIntegerInspectorFactory());
+        builder.contributeMicroOperator(die, runtime, recDesc);
+        ILogicalOperator src = die.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, die, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamLimitPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamLimitPOperator.java
new file mode 100644
index 0000000..11e24d7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamLimitPOperator.java
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.StreamLimitRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class StreamLimitPOperator extends AbstractPhysicalOperator {
+
+    private boolean global;
+
+    public StreamLimitPOperator(boolean global) {
+        this.global = global;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STREAM_LIMIT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        if (global) {
+            StructuralPropertiesVector[] pv = new StructuralPropertiesVector[1];
+            pv[0] = new StructuralPropertiesVector(IPartitioningProperty.UNPARTITIONED, null);
+            return new PhysicalRequirements(pv, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+        } else {
+            return emptyUnaryRequirements();
+        }
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        LimitOperator limit = (LimitOperator) op;
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        IVariableTypeEnvironment env = context.getTypeEnvironment(op);
+        IScalarEvaluatorFactory maxObjectsFact = expressionRuntimeProvider.createEvaluatorFactory(limit.getMaxObjects()
+                .getValue(), env, inputSchemas, context);
+        ILogicalExpression offsetExpr = limit.getOffset().getValue();
+        IScalarEvaluatorFactory offsetFact = (offsetExpr == null) ? null : expressionRuntimeProvider
+                .createEvaluatorFactory(offsetExpr, env, inputSchemas, context);
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        StreamLimitRuntimeFactory runtime = new StreamLimitRuntimeFactory(maxObjectsFact, offsetFact, null,
+                context.getBinaryIntegerInspectorFactory());
+        builder.contributeMicroOperator(limit, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = limit.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, limit, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamProjectPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamProjectPOperator.java
new file mode 100644
index 0000000..54c0505
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamProjectPOperator.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.StreamProjectRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class StreamProjectPOperator extends AbstractPropagatePropertiesForUsedVariablesPOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STREAM_PROJECT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        ProjectOperator project = (ProjectOperator) op;
+        int[] projectionList = new int[project.getVariables().size()];
+        int i = 0;
+        for (LogicalVariable v : project.getVariables()) {
+            int pos = inputSchemas[0].findVariable(v);
+            if (pos < 0) {
+                throw new AlgebricksException("Could not find variable " + v + ".");
+            }
+            projectionList[i++] = pos;
+        }
+        StreamProjectRuntimeFactory runtime = new StreamProjectRuntimeFactory(projectionList);
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        builder.contributeMicroOperator(project, runtime, recDesc);
+        ILogicalOperator src = project.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, project, 0);
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ProjectOperator p = (ProjectOperator) op;
+        computeDeliveredPropertiesForUsedVariables(p, p.getVariables());
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamSelectPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamSelectPOperator.java
new file mode 100644
index 0000000..4352d1f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StreamSelectPOperator.java
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IScalarEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.StreamSelectRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class StreamSelectPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STREAM_SELECT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ILogicalOperator op2 = op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        SelectOperator select = (SelectOperator) op;
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        IScalarEvaluatorFactory cond = expressionRuntimeProvider.createEvaluatorFactory(select.getCondition()
+                .getValue(), context.getTypeEnvironment(op), inputSchemas, context);
+        StreamSelectRuntimeFactory runtime = new StreamSelectRuntimeFactory(cond, null,
+                context.getBinaryBooleanInspectorFactory());
+        // contribute one Asterix framewriter
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(select, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = select.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, select, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StringStreamingScriptPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StringStreamingScriptPOperator.java
new file mode 100644
index 0000000..52f8e0b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/StringStreamingScriptPOperator.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.scripting.IScriptDescription;
+import edu.uci.ics.hyracks.algebricks.core.algebra.scripting.IScriptDescription.ScriptKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.scripting.StringStreamingScriptDescription;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.StringStreamingRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class StringStreamingScriptPOperator extends AbstractPropagatePropertiesForUsedVariablesPOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.STRING_STREAM_SCRIPT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        ScriptOperator scriptOp = (ScriptOperator) op;
+        IScriptDescription scriptDesc = scriptOp.getScriptDescription();
+        if (scriptDesc.getKind() != ScriptKind.STRING_STREAMING) {
+            throw new IllegalStateException();
+        }
+        StringStreamingScriptDescription sssd = (StringStreamingScriptDescription) scriptDesc;
+        StringStreamingRuntimeFactory runtime = new StringStreamingRuntimeFactory(sssd.getCommand(),
+                sssd.getPrinterFactories(), sssd.getFieldDelimiter(), sssd.getParserFactory());
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        builder.contributeMicroOperator(scriptOp, runtime, recDesc);
+        // and contribute one edge from its child
+        ILogicalOperator src = scriptOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, scriptOp, 0);
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        ScriptOperator s = (ScriptOperator) op;
+        computeDeliveredPropertiesForUsedVariables(s, s.getInputVariables());
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SubplanPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SubplanPOperator.java
new file mode 100644
index 0000000..933acce
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/SubplanPOperator.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.AlgebricksPipeline;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.meta.SubplanRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INullWriterFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class SubplanPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.SUBPLAN;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPhysicalPropertiesVector childsProperties = op2.getPhysicalOperator().getDeliveredProperties();
+        List<ILocalStructuralProperty> propsLocal = new ArrayList<ILocalStructuralProperty>();
+        if (childsProperties.getLocalProperties() != null) {
+            propsLocal.addAll(childsProperties.getLocalProperties());
+        }
+        // ... get local properties for newly created variables...
+        SubplanOperator subplan = (SubplanOperator) op;
+        for (ILogicalPlan plan : subplan.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : plan.getRoots()) {
+                AbstractLogicalOperator rOp = (AbstractLogicalOperator) r.getValue();
+                propsLocal.addAll(rOp.getPhysicalOperator().getDeliveredProperties().getLocalProperties());
+            }
+        }
+
+        deliveredProperties = new StructuralPropertiesVector(childsProperties.getPartitioningProperty(), propsLocal);
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        return emptyUnaryRequirements();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        SubplanOperator subplan = (SubplanOperator) op;
+        if (subplan.getNestedPlans().size() != 1) {
+            throw new NotImplementedException("Subplan currently works only for one nested plan with one root.");
+        }
+        AlgebricksPipeline[] subplans = compileSubplans(inputSchemas[0], subplan, opSchema, context);
+        assert (subplans.length == 1);
+        AlgebricksPipeline np = subplans[0];
+        RecordDescriptor inputRecordDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op.getInputs().get(0).getValue()),
+                inputSchemas[0], context);
+        INullWriterFactory[] nullWriterFactories = new INullWriterFactory[np.getOutputWidth()];
+        for (int i = 0; i < nullWriterFactories.length; i++) {
+            nullWriterFactories[i] = context.getNullWriterFactory();
+        }
+        SubplanRuntimeFactory runtime = new SubplanRuntimeFactory(np, nullWriterFactories, inputRecordDesc, null);
+
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(subplan, runtime, recDesc);
+
+        ILogicalOperator src = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, op, 0);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnionAllPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnionAllPOperator.java
new file mode 100644
index 0000000..d3f7851
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnionAllPOperator.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningProperty;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.dataflow.std.union.UnionAllOperatorDescriptor;
+
+public class UnionAllPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.UNION_ALL;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        IPartitioningProperty pp = op2.getDeliveredPhysicalProperties().getPartitioningProperty();
+        this.deliveredProperties = new StructuralPropertiesVector(pp, new ArrayList<ILocalStructuralProperty>(0));
+
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        StructuralPropertiesVector pv0 = StructuralPropertiesVector.EMPTY_PROPERTIES_VECTOR;
+        StructuralPropertiesVector pv1 = StructuralPropertiesVector.EMPTY_PROPERTIES_VECTOR;
+        return new PhysicalRequirements(new StructuralPropertiesVector[] { pv0, pv1 },
+                IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        UnionAllOperator unionOp = (UnionAllOperator) op;
+        int n = unionOp.getVariableMappings().size();
+        int[] leftColumns = new int[n];
+        int[] rightColumns = new int[n];
+        int i = 0;
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> t : unionOp.getVariableMappings()) {
+            int posLeft = inputSchemas[0].findVariable(t.first);
+            leftColumns[i] = posLeft;
+            int posRight = inputSchemas[1].findVariable(t.second);
+            rightColumns[i] = posRight;
+            ++i;
+        }
+
+        IOperatorDescriptorRegistry spec = builder.getJobSpec();
+        RecordDescriptor recordDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+
+        // at algebricks level, union all only accepts two inputs, although at
+        // hyracks
+        // level, there is no restrictions
+        UnionAllOperatorDescriptor opDesc = new UnionAllOperatorDescriptor(spec, 2, recordDescriptor);
+        contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
+        ILogicalOperator src1 = op.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src1, 0, op, 0);
+        ILogicalOperator src2 = op.getInputs().get(1).getValue();
+        builder.contributeGraphEdge(src2, 0, op, 1);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnnestPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnnestPOperator.java
new file mode 100644
index 0000000..38ebec1
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/UnnestPOperator.java
@@ -0,0 +1,89 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression.FunctionKind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenHelper;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IUnnestingEvaluatorFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.std.UnnestRuntimeFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public class UnnestPOperator extends AbstractScanPOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.UNNEST;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema opSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        UnnestOperator unnest = (UnnestOperator) op;
+        if (unnest.getPositionalVariable() != null) {
+            throw new AlgebricksException("Cannot generate runtime for unnest with positional variable "
+                    + unnest.getPositionalVariable());
+        }
+        int outCol = opSchema.findVariable(unnest.getVariable());
+        ILogicalExpression unnestExpr = unnest.getExpressionRef().getValue();
+        IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
+        boolean exit = false;
+        if (unnestExpr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+            exit = true;
+        } else {
+            AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) unnestExpr;
+            if (fce.getKind() != FunctionKind.UNNEST) {
+                exit = true;
+            }
+        }
+        if (exit) {
+            throw new AlgebricksException("Unnest expression " + unnestExpr + " is not an unnesting function call.");
+        }
+        UnnestingFunctionCallExpression agg = (UnnestingFunctionCallExpression) unnestExpr;
+        IUnnestingEvaluatorFactory unnestingFactory = expressionRuntimeProvider.createUnnestingFunctionFactory(agg,
+                context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas, context);
+        int[] projectionList = JobGenHelper.projectAllVariables(opSchema);
+        UnnestRuntimeFactory unnestRuntime = new UnnestRuntimeFactory(outCol, unnestingFactory, projectionList);
+        RecordDescriptor recDesc = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), opSchema, context);
+        builder.contributeMicroOperator(unnest, unnestRuntime, recDesc);
+        ILogicalOperator src = unnest.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, unnest, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/WriteResultPOperator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/WriteResultPOperator.java
new file mode 100644
index 0000000..547fe84
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/WriteResultPOperator.java
@@ -0,0 +1,89 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IDataSource;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPartitioningRequirementsCoordinator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.IPhysicalPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.PhysicalRequirements;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.StructuralPropertiesVector;
+import edu.uci.ics.hyracks.algebricks.core.jobgen.impl.JobGenContext;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public class WriteResultPOperator extends AbstractPhysicalOperator {
+
+    private LogicalVariable payload;
+    private List<LogicalVariable> keys;
+    private IDataSource<?> dataSource;
+
+    public WriteResultPOperator(IDataSource<?> dataSource, LogicalVariable payload, List<LogicalVariable> keys) {
+        this.dataSource = dataSource;
+        this.payload = payload;
+        this.keys = keys;
+    }
+
+    @Override
+    public String toString() {
+        return getOperatorTag().toString() + " " + payload + " " + keys;
+    }
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.WRITE_RESULT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return true;
+    }
+
+    @Override
+    public void computeDeliveredProperties(ILogicalOperator op, IOptimizationContext context) {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        deliveredProperties = (StructuralPropertiesVector) op2.getDeliveredPhysicalProperties().clone();
+    }
+
+    @Override
+    public PhysicalRequirements getRequiredPropertiesForChildren(ILogicalOperator op,
+            IPhysicalPropertiesVector reqdByParent) {
+        List<LogicalVariable> scanVariables = new ArrayList<LogicalVariable>();
+        scanVariables.addAll(keys);
+        scanVariables.add(new LogicalVariable(-1));
+        IPhysicalPropertiesVector r = dataSource.getPropertiesProvider().computePropertiesVector(scanVariables);
+        IPhysicalPropertiesVector[] requirements = new IPhysicalPropertiesVector[1];
+        requirements[0] = r;
+        return new PhysicalRequirements(requirements, IPartitioningRequirementsCoordinator.NO_COORDINATION);
+    }
+
+    @SuppressWarnings({ "rawtypes", "unchecked" })
+    @Override
+    public void contributeRuntimeOperator(IHyracksJobBuilder builder, JobGenContext context, ILogicalOperator op,
+            IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
+            throws AlgebricksException {
+        WriteResultOperator writeResultOp = (WriteResultOperator) op;
+        IMetadataProvider mp = context.getMetadataProvider();
+
+        JobSpecification spec = builder.getJobSpec();
+        Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> runtimeAndConstraints = mp.getWriteResultRuntime(
+                dataSource, propagatedSchema, keys, payload, context, spec);
+
+        builder.contributeHyracksOperator(writeResultOp, runtimeAndConstraints.first);
+        builder.contributeAlgebricksPartitionConstraint(runtimeAndConstraints.first, runtimeAndConstraints.second);
+        ILogicalOperator src = writeResultOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, writeResultOp, 0);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/plan/ALogicalPlanImpl.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/plan/ALogicalPlanImpl.java
new file mode 100644
index 0000000..103f534
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/plan/ALogicalPlanImpl.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.plan;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+
+/*
+ * Author: Guangqiang Li
+ * Created on Jul 9, 2009 
+ */
+public class ALogicalPlanImpl implements ILogicalPlan {
+    private List<Mutable<ILogicalOperator>> roots;
+
+    public ALogicalPlanImpl() {
+        this.roots = new ArrayList<Mutable<ILogicalOperator>>();
+    }
+
+    public ALogicalPlanImpl(List<Mutable<ILogicalOperator>> roots) {
+        this.roots = roots;
+    }
+
+    public ALogicalPlanImpl(Mutable<ILogicalOperator> root) {
+        roots = new ArrayList<Mutable<ILogicalOperator>>(1);
+        roots.add(root);
+    }
+
+    public List<Mutable<ILogicalOperator>> getRoots() {
+        return roots;
+    }
+
+    public void setRoots(List<Mutable<ILogicalOperator>> roots) {
+        this.roots = roots;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java
new file mode 100644
index 0000000..a94c78e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java
@@ -0,0 +1,356 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.common.utils.Triple;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator.Kind;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
+
+public class LogicalOperatorPrettyPrintVisitor implements ILogicalOperatorVisitor<String, Integer> {
+
+    public LogicalOperatorPrettyPrintVisitor() {
+    }
+
+    @Override
+    public String visitAggregateOperator(AggregateOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("aggregate ").append(op.getVariables()).append(" <- ");
+        pprintExprList(op.getExpressions(), buffer);
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitRunningAggregateOperator(RunningAggregateOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("running-aggregate ").append(op.getVariables()).append(" <- ");
+        pprintExprList(op.getExpressions(), buffer);
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("empty-tuple-source");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitGroupByOperator(GroupByOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("group by (").append(op.gByListToString()).append(") decor (")
+                .append(op.decorListToString()).append(") {");
+        printNestedPlans(op, indent, buffer);
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitDistinctOperator(DistinctOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("distinct " + "(");
+        pprintExprList(op.getExpressions(), buffer);
+        buffer.append(")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitInnerJoinOperator(InnerJoinOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("join (").append(op.getCondition().getValue()).append(")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitLeftOuterJoinOperator(LeftOuterJoinOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("left outer join (").append(op.getCondition().getValue()).append(")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitNestedTupleSourceOperator(NestedTupleSourceOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("nested tuple source");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitOrderOperator(OrderOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("order ");
+        for (Pair<OrderOperator.IOrder, Mutable<ILogicalExpression>> p : op.getOrderExpressions()) {
+            String fst;
+            switch (p.first.getKind()) {
+                case ASC: {
+                    fst = "ASC";
+                    break;
+                }
+                case DESC: {
+                    fst = "DESC";
+                    break;
+                }
+                default: {
+                    fst = p.first.getExpressionRef().toString();
+                }
+            }
+            buffer.append("(" + fst + ", " + p.second.getValue() + ") ");
+        }
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitAssignOperator(AssignOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("assign ").append(op.getVariables()).append(" <- ");
+        pprintExprList(op.getExpressions(), buffer);
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitWriteOperator(WriteOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("write ").append(op.getExpressions());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitWriteResultOperator(WriteResultOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("load ").append(op.getDataSource()).append(" from ")
+                .append(op.getPayloadExpression()).append(" partitioned by ").append(op.getKeyExpressions().toString());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitSelectOperator(SelectOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("select " + "(" + op.getCondition().getValue() + ")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitProjectOperator(ProjectOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("project " + "(" + op.getVariables() + ")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitPartitioningSplitOperator(PartitioningSplitOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("partitioning-split (" + op.getExpressions() + ")");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitSubplanOperator(SubplanOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("subplan {");
+        printNestedPlans(op, indent, buffer);
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitUnionOperator(UnionAllOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("union");
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> v : op.getVariableMappings()) {
+            buffer.append(" (" + v.first + ", " + v.second + ", " + v.third + ")");
+        }
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitUnnestOperator(UnnestOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("unnest " + op.getVariable());
+        if (op.getPositionalVariable() != null) {
+            buffer.append(" at " + op.getPositionalVariable());
+        }
+        buffer.append(" <- " + op.getExpressionRef().getValue());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitUnnestMapOperator(UnnestMapOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("unnest-map " + op.getVariables() + " <- " + op.getExpressionRef().getValue());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitDataScanOperator(DataSourceScanOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append(
+                "data-scan " + op.getProjectVariables() + "<-" + op.getVariables() + " <- " + op.getDataSource());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitLimitOperator(LimitOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("limit " + op.getMaxObjects().getValue());
+        ILogicalExpression offset = op.getOffset().getValue();
+        if (offset != null) {
+            buffer.append(", " + offset);
+        }
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitDieOperator(DieOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("die after " + op.getAfterObjects().getValue());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitExchangeOperator(ExchangeOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("exchange ");
+        return buffer.toString();
+    }
+
+    protected static final StringBuilder addIndent(StringBuilder buffer, int level) {
+        for (int i = 0; i < level; ++i) {
+            buffer.append(' ');
+        }
+        return buffer;
+    }
+
+    private void printNestedPlans(AbstractOperatorWithNestedPlans op, Integer indent, StringBuilder buffer)
+            throws AlgebricksException {
+        boolean first = true;
+        if (op.getNestedPlans().isEmpty()) {
+            buffer.append("}");
+        } else {
+            for (ILogicalPlan p : op.getNestedPlans()) {
+                // PrettyPrintUtil.indent(buffer, level + 10).append("var " +
+                // p.first + ":\n");
+                buffer.append("\n");
+                if (first) {
+                    first = false;
+                } else {
+                    addIndent(buffer, indent).append("       {\n");
+                }
+                PlanPrettyPrinter.printPlan(p, buffer, this, indent + 10);
+                addIndent(buffer, indent).append("       }");
+            }
+        }
+    }
+
+    @Override
+    public String visitScriptOperator(ScriptOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append(
+                "script (in: " + op.getInputVariables() + ") (out: " + op.getOutputVariables() + ")");
+        return buffer.toString();
+    }
+
+    private void pprintExprList(List<Mutable<ILogicalExpression>> expressions, StringBuilder buffer) {
+        buffer.append("[");
+        boolean first = true;
+        for (Mutable<ILogicalExpression> exprRef : expressions) {
+            if (first) {
+                first = false;
+            } else {
+                buffer.append(", ");
+            }
+            buffer.append(exprRef.getValue());
+        }
+        buffer.append("]");
+    }
+
+    @Override
+    public String visitReplicateOperator(ReplicateOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("replicate ");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitInsertDeleteOperator(InsertDeleteOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        String header = op.getOperation() == Kind.INSERT ? "insert into " : "delete from ";
+        addIndent(buffer, indent).append(header).append(op.getDataSource()).append(" from ")
+                .append(op.getPayloadExpression()).append(" partitioned by ")
+                .append(op.getPrimaryKeyExpressions().toString());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, Integer indent)
+            throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        String header = op.getOperation() == Kind.INSERT ? "insert into " : "delete from ";
+        addIndent(buffer, indent).append(header).append(op.getDataSourceIndex()).append(" from ")
+                .append(op.getSecondaryKeyExpressions().toString()).append(" ")
+                .append(op.getPrimaryKeyExpressions().toString());
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitSinkOperator(SinkOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("sink");
+        return buffer.toString();
+    }
+
+    @Override
+    public String visitExtensionOperator(ExtensionOperator op, Integer indent) throws AlgebricksException {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("statistics collection");
+        return buffer.toString();
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/PlanPrettyPrinter.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/PlanPrettyPrinter.java
new file mode 100644
index 0000000..aa96513
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/PlanPrettyPrinter.java
@@ -0,0 +1,90 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IPhysicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+
+public class PlanPrettyPrinter {
+    public static void printPlan(ILogicalPlan plan, StringBuilder out, LogicalOperatorPrettyPrintVisitor pvisitor,
+            int indent) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> root : plan.getRoots()) {
+            printOperator((AbstractLogicalOperator) root.getValue(), out, pvisitor, indent);
+        }
+    }
+
+    public static void printPhysicalOps(ILogicalPlan plan, StringBuilder out, int indent) {
+        for (Mutable<ILogicalOperator> root : plan.getRoots()) {
+            printPhysicalOperator((AbstractLogicalOperator) root.getValue(), indent, out);
+        }
+    }
+
+    public static void printOperator(AbstractLogicalOperator op, StringBuilder out,
+            LogicalOperatorPrettyPrintVisitor pvisitor, int indent) throws AlgebricksException {
+        out.append(op.accept(pvisitor, indent));
+        IPhysicalOperator pOp = op.getPhysicalOperator();
+
+        if (pOp != null) {
+            out.append("\n");
+            pad(out, indent);
+            appendln(out, "-- " + pOp.toString() + "  |" + op.getExecutionMode() + "|");
+        } else {
+            appendln(out, " -- |" + op.getExecutionMode() + "|");
+        }
+
+        for (Mutable<ILogicalOperator> i : op.getInputs()) {
+            printOperator((AbstractLogicalOperator) i.getValue(), out, pvisitor, indent + 2);
+        }
+
+    }
+
+    public static void printPhysicalOperator(AbstractLogicalOperator op, int indent, StringBuilder out) {
+        IPhysicalOperator pOp = op.getPhysicalOperator();
+        pad(out, indent);
+        appendln(out, "-- " + pOp.toString() + "  |" + op.getExecutionMode() + "|");
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans opNest = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan p : opNest.getNestedPlans()) {
+                pad(out, indent + 8);
+                appendln(out, "{");
+                printPhysicalOps(p, out, indent + 10);
+                pad(out, indent + 8);
+                appendln(out, "}");
+            }
+        }
+
+        for (Mutable<ILogicalOperator> i : op.getInputs()) {
+            printPhysicalOperator((AbstractLogicalOperator) i.getValue(), indent + 2, out);
+        }
+
+    }
+
+    private static void appendln(StringBuilder buf, String s) {
+        buf.append(s);
+        buf.append("\n");
+    }
+
+    private static void pad(StringBuilder buf, int indent) {
+        for (int i = 0; i < indent; ++i) {
+            buf.append(' ');
+        }
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AbstractGroupingProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AbstractGroupingProperty.java
new file mode 100644
index 0000000..341b4f0
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AbstractGroupingProperty.java
@@ -0,0 +1,86 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public abstract class AbstractGroupingProperty {
+    protected Set<LogicalVariable> columnSet;
+
+    public AbstractGroupingProperty(Set<LogicalVariable> columnSet) {
+        this.columnSet = columnSet;
+    }
+
+    public Set<LogicalVariable> getColumnSet() {
+        return columnSet;
+    }
+
+    public final void normalizeGroupingColumns(Map<LogicalVariable, EquivalenceClass> equivalenceClasses,
+            List<FunctionalDependency> fds) {
+        replaceGroupingColumnsByEqClasses(equivalenceClasses);
+        applyFDsToGroupingColumns(fds);
+    }
+
+    private void replaceGroupingColumnsByEqClasses(Map<LogicalVariable, EquivalenceClass> equivalenceClasses) {
+        if (equivalenceClasses == null || equivalenceClasses.isEmpty()) {
+            return;
+        }
+        Set<LogicalVariable> norm = new ListSet<LogicalVariable>();
+        for (LogicalVariable v : columnSet) {
+            EquivalenceClass ec = equivalenceClasses.get(v);
+            if (ec == null) {
+                norm.add(v);
+            } else {
+                if (ec.representativeIsConst()) {
+                    // trivially satisfied, so the var. can be removed
+                } else {
+                    norm.add(ec.getVariableRepresentative());
+                }
+            }
+        }
+        columnSet = norm;
+    }
+
+    private void applyFDsToGroupingColumns(List<FunctionalDependency> fds) {
+        // the set of vars. is unordered
+        // so we try all FDs on all variables (incomplete algo?)
+        if (fds == null || fds.isEmpty()) {
+            return;
+        }
+        Set<LogicalVariable> norm = new ListSet<LogicalVariable>();
+        for (LogicalVariable v : columnSet) {
+            boolean isImpliedByAnFD = false;
+            for (FunctionalDependency fdep : fds) {
+                if (columnSet.containsAll(fdep.getHead()) && fdep.getTail().contains(v)) {
+                    isImpliedByAnFD = true;
+                    norm.addAll(fdep.getHead());
+                    break;
+                }
+
+            }
+            if (!isImpliedByAnFD) {
+                norm.add(v);
+            }
+        }
+        columnSet = norm;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AsterixNodeGroupDomain.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AsterixNodeGroupDomain.java
new file mode 100644
index 0000000..d27534a
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/AsterixNodeGroupDomain.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+public class AsterixNodeGroupDomain implements INodeDomain {
+
+    private String groupName;
+
+    public AsterixNodeGroupDomain(String groupName) {
+        this.groupName = groupName;
+    }
+
+    @Override
+    public boolean sameAs(INodeDomain domain) {
+        if (!(domain instanceof AsterixNodeGroupDomain)) {
+            return false;
+        }
+        AsterixNodeGroupDomain dom2 = (AsterixNodeGroupDomain) domain;
+        return groupName.equals(dom2.groupName);
+    }
+
+    @Override
+    public String toString() {
+        return "AsterixDomain(" + groupName + ")";
+    }
+
+    @Override
+    public Integer cardinality() {
+        return null;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/BroadcastPartitioningProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/BroadcastPartitioningProperty.java
new file mode 100644
index 0000000..8a38cfb
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/BroadcastPartitioningProperty.java
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class BroadcastPartitioningProperty implements IPartitioningProperty {
+
+    private INodeDomain domain;
+
+    public BroadcastPartitioningProperty(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+    @Override
+    public PartitioningType getPartitioningType() {
+        return PartitioningType.BROADCAST;
+    }
+
+    @Override
+    public void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+        // do nothing
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+    }
+
+    @Override
+    public INodeDomain getNodeDomain() {
+        return domain;
+    }
+
+    @Override
+    public void setNodeDomain(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FileSplitDomain.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FileSplitDomain.java
new file mode 100644
index 0000000..876ee52
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FileSplitDomain.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import edu.uci.ics.hyracks.dataflow.std.file.FileSplit;
+
+public class FileSplitDomain implements INodeDomain {
+
+    private FileSplit[] splits;
+
+    public FileSplitDomain(FileSplit[] splits) {
+        this.splits = splits;
+    }
+
+    @Override
+    public Integer cardinality() {
+        return splits.length;
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("FileSplitDomain[");
+        boolean fst = true;
+        for (FileSplit fs : splits) {
+            if (fst) {
+                fst = false;
+            } else {
+                sb.append(", ");
+            }
+            sb.append(fs.getNodeName() + ":" + fs.getLocalFile());
+        }
+        sb.append(']');
+        return sb.toString();
+    }
+
+    @Override
+    public boolean sameAs(INodeDomain domain) {
+        if (!(domain instanceof FileSplitDomain)) {
+            return false;
+        }
+        FileSplitDomain fsd = (FileSplitDomain) domain;
+        if (fsd.splits.length != splits.length) {
+            return false;
+        }
+        // conservative approach...
+        for (int i = 0; i < splits.length; i++) {
+            if (!ncEq(splits[i], fsd.splits[i])) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    private boolean ncEq(FileSplit fs1, FileSplit fs2) {
+        return fs1.getNodeName().equals(fs2.getNodeName());
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FilteredVariablePropagationPolicy.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FilteredVariablePropagationPolicy.java
new file mode 100644
index 0000000..40bbc36
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FilteredVariablePropagationPolicy.java
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+
+public class FilteredVariablePropagationPolicy extends VariablePropagationPolicy {
+
+    List<LogicalVariable> toPropagate;
+
+    public FilteredVariablePropagationPolicy(List<LogicalVariable> varList) {
+        toPropagate = varList;
+    }
+
+    @Override
+    public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources) {
+        for (LogicalVariable v : toPropagate) {
+            target.addVariable(v);
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FunctionalDependency.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FunctionalDependency.java
new file mode 100644
index 0000000..1c76171
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/FunctionalDependency.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public final class FunctionalDependency {
+    private List<LogicalVariable> head;
+    private List<LogicalVariable> tail;
+
+    public FunctionalDependency(List<LogicalVariable> head, List<LogicalVariable> tail) {
+        this.head = head;
+        this.tail = tail;
+    }
+
+    public List<LogicalVariable> getHead() {
+        return head;
+    }
+
+    public List<LogicalVariable> getTail() {
+        return tail;
+    }
+
+    @Override
+    public String toString() {
+        return head + "->" + tail;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof FunctionalDependency)) {
+            return false;
+        } else {
+            FunctionalDependency fd = (FunctionalDependency) obj;
+            return fd.getHead().equals(this.head) && fd.getTail().equals(this.tail);
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILocalStructuralProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILocalStructuralProperty.java
new file mode 100644
index 0000000..fbe30f5
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILocalStructuralProperty.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface ILocalStructuralProperty extends IStructuralProperty {
+    public enum PropertyType {
+        LOCAL_GROUPING_PROPERTY,
+        LOCAL_ORDER_PROPERTY
+    }
+
+    public void getVariables(Collection<LogicalVariable> variables);
+
+    public PropertyType getPropertyType();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILogicalPropertiesVector.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILogicalPropertiesVector.java
new file mode 100644
index 0000000..214a579
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/ILogicalPropertiesVector.java
@@ -0,0 +1,21 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+public interface ILogicalPropertiesVector {
+    public Integer getNumberOfTuples();
+
+    public Integer getMaxOutputFrames();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/INodeDomain.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/INodeDomain.java
new file mode 100644
index 0000000..76057f6
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/INodeDomain.java
@@ -0,0 +1,22 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+public interface INodeDomain {
+    public boolean sameAs(INodeDomain domain);
+
+    /** @return the number of nodes in that domain or null if unknown */
+    public Integer cardinality();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningProperty.java
new file mode 100644
index 0000000..8a0cab7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningProperty.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IPartitioningProperty extends IStructuralProperty {
+    public enum PartitioningType {
+        UNPARTITIONED, RANDOM, BROADCAST, UNORDERED_PARTITIONED, ORDERED_PARTITIONED
+    }
+
+    static final INodeDomain DOMAIN_FOR_UNPARTITIONED_DATA = new INodeDomain() {
+        @Override
+        public boolean sameAs(INodeDomain domain) {
+            return domain == this;
+        }
+
+        @Override
+        public Integer cardinality() {
+            return null;
+        }
+    };
+
+    public static final IPartitioningProperty UNPARTITIONED = new IPartitioningProperty() {
+
+        @Override
+        public PartitioningType getPartitioningType() {
+            return PartitioningType.UNPARTITIONED;
+        }
+
+        @Override
+        public void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+            // do nothing
+        }
+
+        @Override
+        public void getColumns(Collection<LogicalVariable> columns) {
+        }
+
+        @Override
+        public INodeDomain getNodeDomain() {
+            return DOMAIN_FOR_UNPARTITIONED_DATA;
+        }
+
+        @Override
+        public String toString() {
+            return getPartitioningType().toString();
+        }
+
+        @Override
+        public void setNodeDomain(INodeDomain domain) {
+            throw new IllegalStateException();
+        }
+    };
+
+    public abstract PartitioningType getPartitioningType();
+
+    public abstract void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses,
+            List<FunctionalDependency> fds);
+
+    public abstract INodeDomain getNodeDomain();
+
+    public abstract void setNodeDomain(INodeDomain domain);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningRequirementsCoordinator.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningRequirementsCoordinator.java
new file mode 100644
index 0000000..209f1e8
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPartitioningRequirementsCoordinator.java
@@ -0,0 +1,98 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Map;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.NotImplementedException;
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+/**
+ * Implements constraints in between requirements for the children of the same
+ * operator.
+ */
+
+public interface IPartitioningRequirementsCoordinator {
+
+    public static IPartitioningRequirementsCoordinator NO_COORDINATION = new IPartitioningRequirementsCoordinator() {
+
+        @Override
+        public Pair<Boolean, IPartitioningProperty> coordinateRequirements(IPartitioningProperty requirements,
+                IPartitioningProperty firstDeliveredPartitioning, ILogicalOperator op, IOptimizationContext context) {
+            return new Pair<Boolean, IPartitioningProperty>(true, requirements);
+        }
+    };
+
+    public static IPartitioningRequirementsCoordinator EQCLASS_PARTITIONING_COORDINATOR = new IPartitioningRequirementsCoordinator() {
+
+        @Override
+        public Pair<Boolean, IPartitioningProperty> coordinateRequirements(IPartitioningProperty rqdpp,
+                IPartitioningProperty firstDeliveredPartitioning, ILogicalOperator op, IOptimizationContext context)
+                throws AlgebricksException {
+            if (firstDeliveredPartitioning != null
+                    && firstDeliveredPartitioning.getPartitioningType() == rqdpp.getPartitioningType()) {
+                switch (rqdpp.getPartitioningType()) {
+                    case UNORDERED_PARTITIONED: {
+                        UnorderedPartitionedProperty upp1 = (UnorderedPartitionedProperty) firstDeliveredPartitioning;
+                        Set<LogicalVariable> set1 = upp1.getColumnSet();
+                        UnorderedPartitionedProperty uppreq = (UnorderedPartitionedProperty) rqdpp;
+                        Set<LogicalVariable> modifuppreq = new ListSet<LogicalVariable>();
+                        Map<LogicalVariable, EquivalenceClass> eqmap = context.getEquivalenceClassMap(op);
+                        Set<LogicalVariable> covered = new ListSet<LogicalVariable>();
+
+                        // coordinate from an existing partition property
+                        // (firstDeliveredPartitioning)
+                        for (LogicalVariable v : set1) {
+                            EquivalenceClass ecFirst = eqmap.get(v);
+                            for (LogicalVariable r : uppreq.getColumnSet()) {
+                                EquivalenceClass ec = eqmap.get(r);
+                                if (ecFirst == ec) {
+                                    covered.add(v);
+                                    modifuppreq.add(r);
+                                    break;
+                                }
+                            }
+                        }
+
+                        if (!covered.equals(set1)) {
+                            throw new AlgebricksException("Could not modify " + rqdpp
+                                    + " to agree with partitioning property " + firstDeliveredPartitioning
+                                    + " delivered by previous input operator.");
+                        }
+                        UnorderedPartitionedProperty upp2 = new UnorderedPartitionedProperty(modifuppreq,
+                                rqdpp.getNodeDomain());
+                        return new Pair<Boolean, IPartitioningProperty>(false, upp2);
+                    }
+                    case ORDERED_PARTITIONED: {
+                        throw new NotImplementedException();
+                    }
+                }
+            }
+            return new Pair<Boolean, IPartitioningProperty>(true, rqdpp);
+        }
+
+    };
+
+    public Pair<Boolean, IPartitioningProperty> coordinateRequirements(IPartitioningProperty requirements,
+            IPartitioningProperty firstDeliveredPartitioning, ILogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPhysicalPropertiesVector.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPhysicalPropertiesVector.java
new file mode 100644
index 0000000..72f9683
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPhysicalPropertiesVector.java
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IPhysicalPropertiesVector {
+
+    public IPartitioningProperty getPartitioningProperty();
+
+    public List<ILocalStructuralProperty> getLocalProperties();
+
+    /**
+     * 
+     * @param reqd
+     *            vector of required properties
+     * @param equivalenceClasses
+     * @param fds
+     * @return a vector of properties from pvector that are not delivered by the
+     *         current vector or null if none
+     */
+    public IPhysicalPropertiesVector getUnsatisfiedPropertiesFrom(IPhysicalPropertiesVector reqd,
+            boolean mayExpandProperties, Map<LogicalVariable, EquivalenceClass> equivalenceClasses,
+            List<FunctionalDependency> fds);
+
+    public IPhysicalPropertiesVector clone();
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPropertiesComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPropertiesComputer.java
new file mode 100644
index 0000000..02afec1
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IPropertiesComputer.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+
+public interface IPropertiesComputer {
+
+    // can return null
+    public IPartitioningProperty computePartitioningProperty(ILogicalExpression expr);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IStructuralProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IStructuralProperty.java
new file mode 100644
index 0000000..aabf9e9
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/IStructuralProperty.java
@@ -0,0 +1,23 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IStructuralProperty {
+    public void getColumns(Collection<LogicalVariable> columns);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalGroupingProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalGroupingProperty.java
new file mode 100644
index 0000000..5c82ee7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalGroupingProperty.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class LocalGroupingProperty extends AbstractGroupingProperty implements ILocalStructuralProperty {
+
+    // preferredOrderEnforcer, if not null, is guaranteed to enforce grouping on
+    // columnSet
+    private List<LogicalVariable> preferredOrderEnforcer;
+
+    public LocalGroupingProperty(Set<LogicalVariable> columnSet) {
+        super(columnSet);
+    }
+
+    public LocalGroupingProperty(Set<LogicalVariable> columnSet, List<LogicalVariable> preferredOrderEnforcer) {
+        this(columnSet);
+        this.preferredOrderEnforcer = preferredOrderEnforcer;
+    }
+
+    @Override
+    public PropertyType getPropertyType() {
+        return PropertyType.LOCAL_GROUPING_PROPERTY;
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+        columns.addAll(columnSet);
+    }
+
+    @Override
+    public String toString() {
+        return columnSet.toString();
+    }
+
+    @Override
+    public void getVariables(Collection<LogicalVariable> variables) {
+        variables.addAll(columnSet);
+    }
+
+    public List<LogicalVariable> getPreferredOrderEnforcer() {
+        return preferredOrderEnforcer;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalOrderProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalOrderProperty.java
new file mode 100644
index 0000000..7810df7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LocalOrderProperty.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+
+public final class LocalOrderProperty implements ILocalStructuralProperty {
+
+    private OrderColumn orderColumn;
+
+    public LocalOrderProperty(OrderColumn orderColumn) {
+        this.orderColumn = orderColumn;
+    }
+
+    public OrderColumn getOrderColumn() {
+        return orderColumn;
+    }
+
+    public void setOrderColumn(OrderColumn orderColumn) {
+        this.orderColumn = orderColumn;
+    }
+
+    public LogicalVariable getColumn() {
+        return orderColumn.getColumn();
+    }
+
+    public OrderKind getOrder() {
+        return orderColumn.getOrder();
+    }
+
+    @Override
+    public PropertyType getPropertyType() {
+        return PropertyType.LOCAL_ORDER_PROPERTY;
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+        columns.add(getColumn());
+    }
+
+    @Override
+    public String toString() {
+        return orderColumn.toString();
+    }
+
+    @Override
+    public void getVariables(Collection<LogicalVariable> variables) {
+        variables.add(orderColumn.getColumn());
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LogicalPropertiesVectorImpl.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LogicalPropertiesVectorImpl.java
new file mode 100644
index 0000000..ae25f41
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/LogicalPropertiesVectorImpl.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+public class LogicalPropertiesVectorImpl implements ILogicalPropertiesVector {
+
+    private Integer numTuples, maxOutputFrames;
+
+    @Override
+    public String toString() {
+        return "LogicalPropertiesVector [ num.tuples: " + numTuples + ", maxOutputFrames: " + maxOutputFrames + " ]";
+    }
+
+    @Override
+    public Integer getNumberOfTuples() {
+        return numTuples;
+    }
+
+    public void setNumberOfTuples(Integer numTuples) {
+        this.numTuples = numTuples;
+    }
+
+    @Override
+    public Integer getMaxOutputFrames() {
+        return maxOutputFrames;
+    }
+
+    public void setMaxOutputFrames(Integer maxOutputFrames) {
+        this.maxOutputFrames = maxOutputFrames;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderColumn.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderColumn.java
new file mode 100644
index 0000000..5f22b95
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderColumn.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator.IOrder.OrderKind;
+
+public final class OrderColumn {
+
+    private LogicalVariable column;
+    private OrderKind order;
+
+    public OrderColumn(LogicalVariable column, OrderKind order) {
+        this.column = column;
+        this.order = order;
+    }
+
+    public LogicalVariable getColumn() {
+        return column;
+    }
+
+    public OrderKind getOrder() {
+        return order;
+    }
+
+    public void setColumn(LogicalVariable column) {
+        this.column = column;
+    }
+
+    public void setOrder(OrderKind order) {
+        this.order = order;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof OrderColumn)) {
+            return false;
+        } else {
+            OrderColumn oc = (OrderColumn) obj;
+            return column.equals(oc.getColumn()) && order == oc.getOrder();
+        }
+    }
+
+    @Override
+    public String toString() {
+        return column.toString() + "(" + order + ")";
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderedPartitionedProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderedPartitionedProperty.java
new file mode 100644
index 0000000..137c46d
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/OrderedPartitionedProperty.java
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class OrderedPartitionedProperty implements IPartitioningProperty {
+
+    private ArrayList<OrderColumn> orderColumns;
+    private INodeDomain domain;
+
+    public OrderedPartitionedProperty(ArrayList<OrderColumn> orderColumns, INodeDomain domain) {
+        this.domain = domain;
+        this.orderColumns = orderColumns;
+    }
+
+    public ArrayList<OrderColumn> getOrderColumns() {
+        return orderColumns;
+    }
+
+    public ArrayList<LogicalVariable> getColumns() {
+        ArrayList<LogicalVariable> cols = new ArrayList<LogicalVariable>(orderColumns.size());
+        for (OrderColumn oc : orderColumns) {
+            cols.add(oc.getColumn());
+        }
+        return cols;
+    }
+
+    @Override
+    public PartitioningType getPartitioningType() {
+        return PartitioningType.ORDERED_PARTITIONED;
+    }
+
+    @Override
+    public String toString() {
+        return getPartitioningType().toString() + orderColumns;
+    }
+
+    @Override
+    public void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+        orderColumns = PropertiesUtil.replaceOrderColumnsByEqClasses(orderColumns, equivalenceClasses);
+        orderColumns = PropertiesUtil.applyFDsToOrderColumns(orderColumns, fds);
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+        for (OrderColumn oc : orderColumns) {
+            columns.add(oc.getColumn());
+        }
+    }
+
+    @Override
+    public INodeDomain getNodeDomain() {
+        return domain;
+    }
+
+    @Override
+    public void setNodeDomain(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PhysicalRequirements.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PhysicalRequirements.java
new file mode 100644
index 0000000..7503a3c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PhysicalRequirements.java
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+public class PhysicalRequirements {
+    private final IPhysicalPropertiesVector[] requiredProperties;
+    private final IPartitioningRequirementsCoordinator partitioningCoordinator;
+
+    public PhysicalRequirements(IPhysicalPropertiesVector[] requiredProperties,
+            IPartitioningRequirementsCoordinator partitioningCoordinator) {
+        this.requiredProperties = requiredProperties;
+        this.partitioningCoordinator = partitioningCoordinator;
+    }
+
+    public IPhysicalPropertiesVector[] getRequiredProperties() {
+        return requiredProperties;
+    }
+
+    public IPartitioningRequirementsCoordinator getPartitioningCoordinator() {
+        return partitioningCoordinator;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PropertiesUtil.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PropertiesUtil.java
new file mode 100644
index 0000000..8ca4ccf
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/PropertiesUtil.java
@@ -0,0 +1,322 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.Map;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.ListSet;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILocalStructuralProperty.PropertyType;
+
+public class PropertiesUtil {
+
+    public Set<LogicalVariable> closureUnderFDs(Collection<LogicalVariable> vars, List<FunctionalDependency> fdList) {
+        Set<LogicalVariable> k = new ListSet<LogicalVariable>(vars);
+        boolean change;
+        do {
+            change = false;
+            for (FunctionalDependency fd : fdList) {
+                List<LogicalVariable> h = fd.getHead();
+                if (k.containsAll(h)) {
+                    List<LogicalVariable> t = fd.getTail();
+                    for (LogicalVariable v : t) {
+                        if (!(k.contains(v))) {
+                            k.add(v);
+                            change = true;
+                        }
+                    }
+                }
+            }
+        } while (change);
+        return k;
+    }
+
+    public static boolean matchLocalProperties(List<ILocalStructuralProperty> reqd,
+            List<ILocalStructuralProperty> dlvd, Map<LogicalVariable, EquivalenceClass> equivalenceClasses,
+            List<FunctionalDependency> fds) {
+        if (reqd == null) {
+            return true;
+        }
+        if (dlvd == null) {
+            return false;
+        }
+        normalizeLocals(reqd, equivalenceClasses, fds);
+        normalizeLocals(dlvd, equivalenceClasses, fds);
+
+        ListIterator<ILocalStructuralProperty> dlvdIter = dlvd.listIterator();
+
+        Set<LogicalVariable> rqdCols = new ListSet<LogicalVariable>();
+        Set<LogicalVariable> dlvdCols = new ListSet<LogicalVariable>();
+        for (ILocalStructuralProperty r : reqd) {
+            if (r.getPropertyType() == PropertyType.LOCAL_GROUPING_PROPERTY) {
+                rqdCols.clear();
+                r.getVariables(rqdCols);
+            }
+            boolean implied = false;
+            while (!implied && dlvdIter.hasNext()) {
+                ILocalStructuralProperty d = dlvdIter.next();
+                switch (r.getPropertyType()) {
+                    case LOCAL_ORDER_PROPERTY: {
+                        if (d.getPropertyType() != PropertyType.LOCAL_ORDER_PROPERTY) {
+                            return false;
+                        }
+                        LocalOrderProperty lop = (LocalOrderProperty) d;
+                        if (lop.getColumn() == ((LocalOrderProperty) r).getColumn()
+                                && lop.getOrder() == ((LocalOrderProperty) r).getOrder()) {
+                            implied = true;
+                        } else {
+                            return false;
+                        }
+                        break;
+                    }
+                    case LOCAL_GROUPING_PROPERTY: {
+                        dlvdCols.clear();
+                        d.getColumns(dlvdCols);
+                        for (LogicalVariable v : dlvdCols) {
+                            if (rqdCols.contains(v)) {
+                                rqdCols.remove(v);
+                            } else {
+                                return false;
+                            }
+                        }
+                        if (rqdCols.isEmpty()) {
+                            implied = true;
+                        }
+                        break;
+                    }
+                    default: {
+                        throw new IllegalStateException();
+                    }
+                }
+            }
+            if (!implied) {
+                return false;
+            }
+        }
+        return true;
+
+    }
+
+    public static boolean matchPartitioningProps(IPartitioningProperty reqd, IPartitioningProperty dlvd,
+            boolean mayExpandProperties) {
+
+        INodeDomain dom1 = reqd.getNodeDomain();
+        INodeDomain dom2 = dlvd.getNodeDomain();
+        if (dom1 != null && dom2 != null && !dom1.sameAs(dom2)) {
+            return false;
+        }
+
+        switch (reqd.getPartitioningType()) {
+            case RANDOM: {
+                // anything matches RANDOM
+                return true;
+            }
+            case UNORDERED_PARTITIONED: {
+                switch (dlvd.getPartitioningType()) {
+                    case UNORDERED_PARTITIONED: {
+                        UnorderedPartitionedProperty ur = (UnorderedPartitionedProperty) reqd;
+                        UnorderedPartitionedProperty ud = (UnorderedPartitionedProperty) dlvd;
+                        if (mayExpandProperties) {
+                            return ur.getColumnSet().containsAll(ud.getColumnSet());
+                        } else {
+                            return ur.getColumnSet().equals(ud.getColumnSet());
+                        }
+                    }
+                    case ORDERED_PARTITIONED: {
+                        UnorderedPartitionedProperty ur = (UnorderedPartitionedProperty) reqd;
+                        OrderedPartitionedProperty od = (OrderedPartitionedProperty) dlvd;
+                        if (mayExpandProperties) {
+                            return ur.getColumnSet().containsAll(od.getOrderColumns());
+                        } else {
+                            return ur.getColumnSet().containsAll(od.getOrderColumns())
+                                    && od.getOrderColumns().containsAll(ur.getColumnSet());
+                        }
+                    }
+                    default: {
+                        return false;
+                    }
+                }
+            }
+            case ORDERED_PARTITIONED: {
+                switch (dlvd.getPartitioningType()) {
+                    case ORDERED_PARTITIONED: {
+                        OrderedPartitionedProperty or = (OrderedPartitionedProperty) reqd;
+                        OrderedPartitionedProperty od = (OrderedPartitionedProperty) dlvd;
+                        if (mayExpandProperties) {
+                            return isPrefixOf(od.getOrderColumns(), or.getOrderColumns());
+                        } else {
+                            return od.getOrderColumns().equals(or.getOrderColumns());
+                        }
+                    }
+                    default: {
+                        return false;
+                    }
+                }
+            }
+            default: {
+                return (dlvd.getPartitioningType() == reqd.getPartitioningType());
+            }
+        }
+    }
+
+    /**
+     * @param pref
+     * @param target
+     * @return true iff pref is a prefix of target
+     */
+    private static boolean isPrefixOf(List<OrderColumn> pref, List<OrderColumn> target) {
+        Iterator<OrderColumn> iter = target.iterator();
+        for (OrderColumn v : pref) {
+            if (!iter.hasNext()) {
+                return false;
+            }
+            if (!v.equals(iter.next())) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static ArrayList<OrderColumn> applyFDsToOrderColumns(ArrayList<OrderColumn> orderColumns,
+            List<FunctionalDependency> fds) {
+        // the set of vars. is ordered
+        // so we try the variables in order from last to first
+        if (fds == null || fds.isEmpty()) {
+            return orderColumns;
+        }
+
+        int deleted = 0;
+        for (int i = orderColumns.size() - 1; i >= 0; i--) {
+            for (FunctionalDependency fdep : fds) {
+                if (impliedByPrefix(orderColumns, i, fdep)) {
+                    orderColumns.set(i, null);
+                    deleted++;
+                    break;
+                }
+            }
+        }
+        ArrayList<OrderColumn> norm = new ArrayList<OrderColumn>(orderColumns.size() - deleted);
+        for (OrderColumn oc : orderColumns) {
+            if (oc != null) {
+                norm.add(oc);
+            }
+        }
+        return norm;
+    }
+
+    public static ArrayList<OrderColumn> replaceOrderColumnsByEqClasses(ArrayList<OrderColumn> orderColumns,
+            Map<LogicalVariable, EquivalenceClass> equivalenceClasses) {
+        if (equivalenceClasses == null || equivalenceClasses.isEmpty()) {
+            return orderColumns;
+        }
+        ArrayList<OrderColumn> norm = new ArrayList<OrderColumn>();
+        for (OrderColumn v : orderColumns) {
+            EquivalenceClass ec = equivalenceClasses.get(v.getColumn());
+            if (ec == null) {
+                norm.add(v);
+            } else {
+                if (ec.representativeIsConst()) {
+                    // trivially satisfied, so the var. can be removed
+                } else {
+                    norm.add(new OrderColumn(ec.getVariableRepresentative(), v.getOrder()));
+                }
+            }
+        }
+        return norm;
+    }
+
+    private static boolean impliedByPrefix(ArrayList<OrderColumn> vars, int i, FunctionalDependency fdep) {
+        if (!fdep.getTail().contains(vars.get(i).getColumn())) {
+            return false;
+        }
+        boolean fdSat = true;
+        for (LogicalVariable pv : fdep.getHead()) {
+            boolean isInPrefix = false;
+            for (int j = 0; j < i; j++) {
+                if (vars.get(j).getColumn().equals(pv)) {
+                    isInPrefix = true;
+                    break;
+                }
+            }
+            if (!isInPrefix) {
+                fdSat = false;
+                break;
+            }
+        }
+        return fdSat;
+    }
+
+    private static void normalizeLocals(List<ILocalStructuralProperty> props,
+            Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+        ListIterator<ILocalStructuralProperty> propIter = props.listIterator();
+        int pos = -1;
+        while (propIter.hasNext()) {
+            ILocalStructuralProperty p = propIter.next();
+            if (p.getPropertyType() == PropertyType.LOCAL_GROUPING_PROPERTY) {
+                ((LocalGroupingProperty) p).normalizeGroupingColumns(equivalenceClasses, fds);
+                pos++;
+            } else {
+                LocalOrderProperty ord = (LocalOrderProperty) p;
+                EquivalenceClass ec = equivalenceClasses.get(ord.getColumn());
+                if (ec != null) {
+                    if (ec.representativeIsConst()) {
+                        propIter.remove();
+                    } else {
+                        ord.getOrderColumn().setColumn(ec.getVariableRepresentative());
+                        pos++;
+                    }
+                } else {
+                    pos++;
+                }
+            }
+        }
+
+        if (pos < 1) {
+            return;
+        }
+
+        while (propIter.hasPrevious()) {
+            ILocalStructuralProperty p = propIter.previous();
+            ListIterator<ILocalStructuralProperty> secondIter = props.listIterator(pos);
+            pos--;
+            Set<LogicalVariable> cols = new ListSet<LogicalVariable>();
+            while (secondIter.hasPrevious()) {
+                secondIter.previous().getColumns(cols);
+            }
+            secondIter = null;
+            for (FunctionalDependency fdep : fds) {
+                LinkedList<LogicalVariable> columnsOfP = new LinkedList<LogicalVariable>();
+                p.getColumns(columnsOfP);
+                if (impliedByPrefix(columnsOfP, cols, fdep)) {
+                    propIter.remove();
+                    break;
+                }
+            }
+        }
+    }
+
+    private static boolean impliedByPrefix(List<LogicalVariable> colsOfProp, Set<LogicalVariable> colsOfPrefix,
+            FunctionalDependency fdep) {
+        return fdep.getTail().containsAll(colsOfProp) && colsOfPrefix.containsAll(fdep.getHead());
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/RandomPartitioningProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/RandomPartitioningProperty.java
new file mode 100644
index 0000000..66e900e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/RandomPartitioningProperty.java
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class RandomPartitioningProperty implements IPartitioningProperty {
+
+    private INodeDomain domain;
+
+    public RandomPartitioningProperty(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+    @Override
+    public PartitioningType getPartitioningType() {
+        return PartitioningType.RANDOM;
+    }
+
+    @Override
+    public String toString() {
+        return getPartitioningType() + " domain:" + domain;
+    }
+
+    @Override
+    public void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+        // do nothing
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+    }
+
+    @Override
+    public INodeDomain getNodeDomain() {
+        return domain;
+    }
+
+    @Override
+    public void setNodeDomain(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/StructuralPropertiesVector.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/StructuralPropertiesVector.java
new file mode 100644
index 0000000..d8d8f35
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/StructuralPropertiesVector.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public class StructuralPropertiesVector implements IPhysicalPropertiesVector {
+    private List<ILocalStructuralProperty> propsLocal;
+    private IPartitioningProperty propPartitioning;
+
+    public static final StructuralPropertiesVector EMPTY_PROPERTIES_VECTOR = new StructuralPropertiesVector(null,
+            new ArrayList<ILocalStructuralProperty>());
+
+    public StructuralPropertiesVector(IPartitioningProperty propPartitioning, List<ILocalStructuralProperty> propsLocal) {
+        this.propPartitioning = propPartitioning;
+        this.propsLocal = propsLocal;
+    }
+
+    @Override
+    public String toString() {
+        return "propsLocal=" + propsLocal + "\tpropPartioning=" + propPartitioning;
+    }
+
+    @Override
+    public IPartitioningProperty getPartitioningProperty() {
+        return propPartitioning;
+    }
+
+    @Override
+    public List<ILocalStructuralProperty> getLocalProperties() {
+        return propsLocal;
+    }
+
+    @Override
+    public IPhysicalPropertiesVector clone() {
+        List<ILocalStructuralProperty> propsCopy = new LinkedList<ILocalStructuralProperty>();
+        if (propsLocal != null) {
+            propsCopy.addAll(propsLocal);
+        }
+        return new StructuralPropertiesVector(propPartitioning, propsCopy);
+    }
+
+    /**
+     * 
+     * @param reqd
+     *            vector of required properties
+     * @return a vector of properties from pvector that are not delivered by the
+     *         current vector or null if none
+     */
+    @Override
+    public IPhysicalPropertiesVector getUnsatisfiedPropertiesFrom(IPhysicalPropertiesVector reqd,
+            boolean mayExpandProperties, Map<LogicalVariable, EquivalenceClass> equivalenceClasses,
+            List<FunctionalDependency> fds) {
+        List<ILocalStructuralProperty> plist = reqd.getLocalProperties();
+        List<ILocalStructuralProperty> diffLocals = null;
+        if (plist != null && !plist.isEmpty()) {
+            if (!PropertiesUtil.matchLocalProperties(plist, propsLocal, equivalenceClasses, fds)) {
+                diffLocals = plist;
+            }
+        }
+
+        IPartitioningProperty diffPart = null;
+        IPartitioningProperty reqdPart = reqd.getPartitioningProperty();
+        if (reqdPart != null) {
+            if (mayExpandProperties) {
+                reqdPart.normalize(equivalenceClasses, fds);
+            } else {
+                reqdPart.normalize(equivalenceClasses, null);
+            }
+            propPartitioning.normalize(equivalenceClasses, fds);
+            if (!PropertiesUtil.matchPartitioningProps(reqdPart, propPartitioning, mayExpandProperties)) {
+                diffPart = reqdPart;
+            }
+        }
+
+        if (diffLocals == null && diffPart == null) {
+            return null;
+        } else {
+            return new StructuralPropertiesVector(diffPart, diffLocals);
+        }
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/TypePropagationPolicy.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/TypePropagationPolicy.java
new file mode 100644
index 0000000..01c2de4
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/TypePropagationPolicy.java
@@ -0,0 +1,68 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypeEnvPointer;
+
+public abstract class TypePropagationPolicy {
+    public static final TypePropagationPolicy ALL = new TypePropagationPolicy() {
+
+        @Override
+        public Object getVarType(LogicalVariable var, INullableTypeComputer ntc,
+                List<LogicalVariable> nonNullVariableList, ITypeEnvPointer... typeEnvs) throws AlgebricksException {
+            for (ITypeEnvPointer p : typeEnvs) {
+                IVariableTypeEnvironment env = p.getTypeEnv();
+                if (env == null) {
+                    throw new AlgebricksException("Null environment for pointer " + p + " in getVarType for var=" + var);
+                }
+                Object t = env.getVarType(var, nonNullVariableList);
+                if (t != null) {
+                    return t;
+                }
+            }
+            return null;
+        }
+    };
+
+    public static final TypePropagationPolicy LEFT_OUTER = new TypePropagationPolicy() {
+
+        @Override
+        public Object getVarType(LogicalVariable var, INullableTypeComputer ntc,
+                List<LogicalVariable> nonNullVariableList, ITypeEnvPointer... typeEnvs) throws AlgebricksException {
+            int n = typeEnvs.length;
+            for (int i = 0; i < n; i++) {
+                Object t = typeEnvs[i].getTypeEnv().getVarType(var, nonNullVariableList);
+                if (t != null) {
+                    if (i == 0) { // inner branch
+                        return t;
+                    } else { // outer branch
+                        boolean nonNullVarIsProduced = false;
+                        for (LogicalVariable v : nonNullVariableList) {
+                            if (v == var) {
+                                nonNullVarIsProduced = true;
+                                break;
+                            }
+                            if (typeEnvs[i].getTypeEnv().getVarType(v) != null) {
+                                nonNullVarIsProduced = true;
+                                break;
+                            }
+                        }
+                        if (nonNullVarIsProduced) {
+                            return t;
+                        } else {
+                            return ntc.makeNullableType(t);
+                        }
+                    }
+                }
+            }
+            return null;
+        }
+    };
+
+    public abstract Object getVarType(LogicalVariable var, INullableTypeComputer ntc,
+            List<LogicalVariable> nonNullVariableList, ITypeEnvPointer... typeEnvs) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnorderedPartitionedProperty.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnorderedPartitionedProperty.java
new file mode 100644
index 0000000..520e7db
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnorderedPartitionedProperty.java
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public final class UnorderedPartitionedProperty extends AbstractGroupingProperty implements IPartitioningProperty {
+
+    private INodeDomain domain;
+
+    public UnorderedPartitionedProperty(Set<LogicalVariable> partitioningVariables, INodeDomain domain) {
+        super(partitioningVariables);
+        this.domain = domain;
+    }
+
+    @Override
+    public PartitioningType getPartitioningType() {
+        return PartitioningType.UNORDERED_PARTITIONED;
+    }
+
+    @Override
+    public void normalize(Map<LogicalVariable, EquivalenceClass> equivalenceClasses, List<FunctionalDependency> fds) {
+        normalizeGroupingColumns(equivalenceClasses, fds);
+    }
+
+    @Override
+    public String toString() {
+        return getPartitioningType().toString() + columnSet;
+    }
+
+    @Override
+    public void getColumns(Collection<LogicalVariable> columns) {
+        columns.addAll(columnSet);
+    }
+
+    @Override
+    public INodeDomain getNodeDomain() {
+        return domain;
+    }
+
+    @Override
+    public void setNodeDomain(INodeDomain domain) {
+        this.domain = domain;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnpartitionedPropertyComputer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnpartitionedPropertyComputer.java
new file mode 100644
index 0000000..acdecba
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/UnpartitionedPropertyComputer.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+
+public class UnpartitionedPropertyComputer implements IPropertiesComputer {
+
+    public static final UnpartitionedPropertyComputer INSTANCE = new UnpartitionedPropertyComputer();
+
+    private UnpartitionedPropertyComputer() {
+    }
+
+    @Override
+    public IPartitioningProperty computePartitioningProperty(ILogicalExpression expr) {
+        return IPartitioningProperty.UNPARTITIONED;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/VariablePropagationPolicy.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/VariablePropagationPolicy.java
new file mode 100644
index 0000000..f9c4ac3
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/properties/VariablePropagationPolicy.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.properties;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+
+public abstract class VariablePropagationPolicy {
+    public static final VariablePropagationPolicy ALL = new VariablePropagationPolicy() {
+        @Override
+        public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources) {
+            int n = sources.length;
+            for (int i = 0; i < n; i++) {
+                target.addAllNewVariables(sources[i]);
+            }
+        }
+    };
+
+    public static final VariablePropagationPolicy NONE = new VariablePropagationPolicy() {
+        @Override
+        public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources) {
+            // do nothing
+        }
+    };
+
+    /**
+     * Adds, from each source, only variables that do not already appear in the
+     * target.
+     * 
+     * 
+     */
+    public static final VariablePropagationPolicy ADDNEWVARIABLES = new VariablePropagationPolicy() {
+        @Override
+        public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources) {
+            for (IOperatorSchema s : sources) {
+                for (LogicalVariable v : s) {
+                    if (target.findVariable(v) < 0) {
+                        target.addVariable(v);
+                    }
+                }
+            }
+        }
+    };
+
+    public abstract void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+            throws AlgebricksException;
+
+    public static VariablePropagationPolicy concat(final VariablePropagationPolicy... policies) {
+        return new VariablePropagationPolicy() {
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                if (policies.length != sources.length) {
+                    throw new IllegalArgumentException();
+                }
+                for (int i = 0; i < policies.length; ++i) {
+                    VariablePropagationPolicy p = policies[i];
+                    IOperatorSchema s = sources[i];
+                    p.propagateVariables(target, s);
+                }
+            }
+        };
+    }
+
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/IScriptDescription.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/IScriptDescription.java
new file mode 100644
index 0000000..89f40d6
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/IScriptDescription.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.scripting;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+
+public interface IScriptDescription {
+    public enum ScriptKind {
+        STRING_STREAMING
+    }
+
+    public ScriptKind getKind();
+
+    public List<Pair<LogicalVariable, Object>> getVarTypePairs();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/StringStreamingScriptDescription.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/StringStreamingScriptDescription.java
new file mode 100644
index 0000000..f41535f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/scripting/StringStreamingScriptDescription.java
@@ -0,0 +1,66 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.scripting;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
+import edu.uci.ics.hyracks.dataflow.std.file.ITupleParserFactory;
+
+public class StringStreamingScriptDescription implements IScriptDescription {
+
+    private final String command;
+    private final IPrinterFactory[] printerFactories;
+    private final char fieldDelimiter;
+    private final ITupleParserFactory parserFactory;
+    private final List<Pair<LogicalVariable, Object>> varTypePairs;
+
+    public StringStreamingScriptDescription(String command, IPrinterFactory[] printerFactories, char fieldDelimiter,
+            ITupleParserFactory parserFactory, List<Pair<LogicalVariable, Object>> varTypePairs) {
+        this.command = command;
+        this.printerFactories = printerFactories;
+        this.fieldDelimiter = fieldDelimiter;
+        this.parserFactory = parserFactory;
+        this.varTypePairs = varTypePairs;
+    }
+
+    @Override
+    public ScriptKind getKind() {
+        return ScriptKind.STRING_STREAMING;
+    }
+
+    public String getCommand() {
+        return command;
+    }
+
+    public IPrinterFactory[] getPrinterFactories() {
+        return printerFactories;
+    }
+
+    public char getFieldDelimiter() {
+        return fieldDelimiter;
+    }
+
+    public ITupleParserFactory getParserFactory() {
+        return parserFactory;
+    }
+
+    @Override
+    public List<Pair<LogicalVariable, Object>> getVarTypePairs() {
+        return varTypePairs;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/AbstractTypeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/AbstractTypeEnvironment.java
new file mode 100644
index 0000000..e0217a9
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/AbstractTypeEnvironment.java
@@ -0,0 +1,45 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public abstract class AbstractTypeEnvironment implements IVariableTypeEnvironment {
+
+    protected final Map<LogicalVariable, Object> varTypeMap = new HashMap<LogicalVariable, Object>();
+    protected final IExpressionTypeComputer expressionTypeComputer;
+    protected final IMetadataProvider<?, ?> metadataProvider;
+
+    public AbstractTypeEnvironment(IExpressionTypeComputer expressionTypeComputer,
+            IMetadataProvider<?, ?> metadataProvider) {
+        this.expressionTypeComputer = expressionTypeComputer;
+        this.metadataProvider = metadataProvider;
+    }
+
+    @Override
+    public Object getType(ILogicalExpression expr) throws AlgebricksException {
+        return expressionTypeComputer.getType(expr, metadataProvider, this);
+    }
+
+    @Override
+    public void setVarType(LogicalVariable var, Object type) {
+        varTypeMap.put(var, type);
+    }
+
+    @Override
+    public boolean substituteProducedVariable(LogicalVariable v1, LogicalVariable v2) throws AlgebricksException {
+        Object t = varTypeMap.get(v1);
+        if (t == null) {
+            return false;
+        }
+        varTypeMap.put(v1, null);
+        varTypeMap.put(v2, t);
+        return true;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypeEnvPointer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypeEnvPointer.java
new file mode 100644
index 0000000..3c8d674
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypeEnvPointer.java
@@ -0,0 +1,7 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+
+public interface ITypeEnvPointer {
+    public IVariableTypeEnvironment getTypeEnv();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypingContext.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypingContext.java
new file mode 100644
index 0000000..4996b48
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/ITypingContext.java
@@ -0,0 +1,19 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public interface ITypingContext {
+    public abstract IVariableTypeEnvironment getOutputTypeEnvironment(ILogicalOperator op);
+
+    public abstract void setOutputTypeEnvironment(ILogicalOperator op, IVariableTypeEnvironment env);
+
+    public abstract IExpressionTypeComputer getExpressionTypeComputer();
+
+    public abstract INullableTypeComputer getNullableTypeComputer();
+
+    public abstract IMetadataProvider<?, ?> getMetadataProvider();
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/NonPropagatingTypeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/NonPropagatingTypeEnvironment.java
new file mode 100644
index 0000000..00cbac8
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/NonPropagatingTypeEnvironment.java
@@ -0,0 +1,27 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public class NonPropagatingTypeEnvironment extends AbstractTypeEnvironment {
+
+    public NonPropagatingTypeEnvironment(IExpressionTypeComputer expressionTypeComputer,
+            IMetadataProvider<?, ?> metadataProvider) {
+        super(expressionTypeComputer, metadataProvider);
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var) throws AlgebricksException {
+        return varTypeMap.get(var);
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariables) throws AlgebricksException {
+        return getVarType(var);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/OpRefTypeEnvPointer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/OpRefTypeEnvPointer.java
new file mode 100644
index 0000000..417b900
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/OpRefTypeEnvPointer.java
@@ -0,0 +1,28 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+
+public class OpRefTypeEnvPointer implements ITypeEnvPointer {
+
+    private final Mutable<ILogicalOperator> op;
+    private final ITypingContext ctx;
+
+    public OpRefTypeEnvPointer(Mutable<ILogicalOperator> op, ITypingContext ctx) {
+        this.op = op;
+        this.ctx = ctx;
+    }
+
+    @Override
+    public IVariableTypeEnvironment getTypeEnv() {
+        return ctx.getOutputTypeEnvironment(op.getValue());
+    }
+
+    @Override
+    public String toString() {
+        return this.getClass().getName() + ":" + op;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagateOperatorInputsTypeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagateOperatorInputsTypeEnvironment.java
new file mode 100644
index 0000000..5a42caf
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagateOperatorInputsTypeEnvironment.java
@@ -0,0 +1,60 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+public class PropagateOperatorInputsTypeEnvironment extends AbstractTypeEnvironment {
+
+    private final List<LogicalVariable> nonNullVariables = new ArrayList<LogicalVariable>();
+    private final ILogicalOperator op;
+    private final ITypingContext ctx;
+
+    public PropagateOperatorInputsTypeEnvironment(ILogicalOperator op, ITypingContext ctx,
+            IExpressionTypeComputer expressionTypeComputer, IMetadataProvider<?, ?> metadataProvider) {
+        super(expressionTypeComputer, metadataProvider);
+        this.op = op;
+        this.ctx = ctx;
+    }
+
+    public List<LogicalVariable> getNonNullVariables() {
+        return nonNullVariables;
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariableList) throws AlgebricksException {
+        nonNullVariableList.addAll(nonNullVariables);
+        return getVarTypeFullList(var, nonNullVariableList);
+    }
+
+    private Object getVarTypeFullList(LogicalVariable var, List<LogicalVariable> nonNullVariableList)
+            throws AlgebricksException {
+        Object t = varTypeMap.get(var);
+        if (t != null) {
+            return t;
+        }
+        for (Mutable<ILogicalOperator> r : op.getInputs()) {
+            ILogicalOperator c = r.getValue();
+            IVariableTypeEnvironment env = ctx.getOutputTypeEnvironment(c);
+            Object t2 = env.getVarType(var, nonNullVariableList);
+            if (t2 != null) {
+                return t2;
+            }
+        }
+        return null;
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var) throws AlgebricksException {
+        return getVarTypeFullList(var, nonNullVariables);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagatingTypeEnvironment.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagatingTypeEnvironment.java
new file mode 100644
index 0000000..d73e89f
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/typing/PropagatingTypeEnvironment.java
@@ -0,0 +1,55 @@
+package edu.uci.ics.hyracks.algebricks.core.algebra.typing;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.TypePropagationPolicy;
+
+public class PropagatingTypeEnvironment extends AbstractTypeEnvironment {
+
+    private final TypePropagationPolicy policy;
+
+    private final INullableTypeComputer nullableTypeComputer;
+
+    private final ITypeEnvPointer[] envPointers;
+
+    private final List<LogicalVariable> nonNullVariables = new ArrayList<LogicalVariable>();
+
+    public PropagatingTypeEnvironment(IExpressionTypeComputer expressionTypeComputer,
+            INullableTypeComputer nullableTypeComputer, IMetadataProvider<?, ?> metadataProvider,
+            TypePropagationPolicy policy, ITypeEnvPointer[] envPointers) {
+        super(expressionTypeComputer, metadataProvider);
+        this.nullableTypeComputer = nullableTypeComputer;
+        this.policy = policy;
+        this.envPointers = envPointers;
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var) throws AlgebricksException {
+        return getVarTypeFullList(var, nonNullVariables);
+    }
+
+    public List<LogicalVariable> getNonNullVariables() {
+        return nonNullVariables;
+    }
+
+    @Override
+    public Object getVarType(LogicalVariable var, List<LogicalVariable> nonNullVariableList) throws AlgebricksException {
+        nonNullVariableList.addAll(nonNullVariables);
+        return getVarTypeFullList(var, nonNullVariableList);
+    }
+
+    private Object getVarTypeFullList(LogicalVariable var, List<LogicalVariable> nonNullVariableList)
+            throws AlgebricksException {
+        Object t = varTypeMap.get(var);
+        if (t != null) {
+            return t;
+        }
+        return policy.getVarType(var, nullableTypeComputer, nonNullVariableList, envPointers);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java
new file mode 100644
index 0000000..47a979c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java
@@ -0,0 +1,161 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.util;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+
+public class OperatorManipulationUtil {
+
+    // Transforms all NestedTupleSource operators to EmptyTupleSource operators
+    public static void ntsToEts(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        if (op.getOperatorTag() == LogicalOperatorTag.NESTEDTUPLESOURCE) {
+            EmptyTupleSourceOperator ets = new EmptyTupleSourceOperator();
+            context.computeAndSetTypeEnvironmentForOperator(ets);
+            opRef.setValue(ets);
+        } else {
+            for (Mutable<ILogicalOperator> i : opRef.getValue().getInputs()) {
+                ntsToEts(i, context);
+            }
+        }
+    }
+
+    public static ILogicalOperator eliminateSingleSubplanOverEts(SubplanOperator subplan) {
+        if (subplan.getNestedPlans().size() > 1) {
+            // not a single subplan
+            List<Mutable<ILogicalOperator>> subInpList = subplan.getInputs();
+            subInpList.clear();
+            subInpList.add(new MutableObject<ILogicalOperator>(new EmptyTupleSourceOperator()));
+            return subplan;
+        }
+        ILogicalPlan plan = subplan.getNestedPlans().get(0);
+        if (plan.getRoots().size() > 1) {
+            // not a single subplan
+            List<Mutable<ILogicalOperator>> subInpList = subplan.getInputs();
+            subInpList.clear();
+            subInpList.add(new MutableObject<ILogicalOperator>(new EmptyTupleSourceOperator()));
+            return subplan;
+        }
+        return plan.getRoots().get(0).getValue();
+    }
+
+    public static boolean setOperatorMode(AbstractLogicalOperator op) {
+        boolean change = false;
+        switch (op.getOperatorTag()) {
+            case DATASOURCESCAN: {
+                // ILogicalExpression e = ((UnnestOperator) op).getExpression();
+                // if (AnalysisUtil.isDataSetCall(e)) {
+                op.setExecutionMode(AbstractLogicalOperator.ExecutionMode.PARTITIONED);
+                AbstractLogicalOperator child = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+                if (child.getOperatorTag() == LogicalOperatorTag.EMPTYTUPLESOURCE) {
+                    child.setExecutionMode(AbstractLogicalOperator.ExecutionMode.PARTITIONED);
+                }
+                change = true;
+                // }
+                break;
+            }
+            case NESTEDTUPLESOURCE: {
+                NestedTupleSourceOperator nts = (NestedTupleSourceOperator) op;
+                AbstractLogicalOperator prevOp = (AbstractLogicalOperator) nts.getDataSourceReference().getValue()
+                        .getInputs().get(0).getValue();
+                if (prevOp.getExecutionMode() != AbstractLogicalOperator.ExecutionMode.UNPARTITIONED) {
+                    nts.setExecutionMode(AbstractLogicalOperator.ExecutionMode.LOCAL);
+                    change = true;
+                }
+                break;
+            }
+            default: {
+                if (op.getOperatorTag() == LogicalOperatorTag.LIMIT) {
+                    LimitOperator opLim = (LimitOperator) op;
+                    if (opLim.isTopmostLimitOp()) {
+                        if (opLim.getExecutionMode() != AbstractLogicalOperator.ExecutionMode.UNPARTITIONED) {
+                            opLim.setExecutionMode(AbstractLogicalOperator.ExecutionMode.UNPARTITIONED);
+                            change = true;
+                        }
+                        break;
+                    }
+                }
+
+                for (Mutable<ILogicalOperator> i : op.getInputs()) {
+                    boolean exit = false;
+                    AbstractLogicalOperator inputOp = (AbstractLogicalOperator) i.getValue();
+                    switch (inputOp.getExecutionMode()) {
+                        case PARTITIONED: {
+                            op.setExecutionMode(AbstractLogicalOperator.ExecutionMode.PARTITIONED);
+                            change = true;
+                            exit = true;
+                            break;
+                        }
+                        case LOCAL: {
+                            op.setExecutionMode(AbstractLogicalOperator.ExecutionMode.LOCAL);
+                            change = true;
+                            break;
+                        }
+                    }
+                    if (exit) {
+                        break;
+                    }
+                }
+                break;
+            }
+        }
+        return change;
+    }
+
+    public static void substituteVarRec(AbstractLogicalOperator op, LogicalVariable v1, LogicalVariable v2,
+            boolean goThroughNts, ITypingContext ctx) throws AlgebricksException {
+        VariableUtilities.substituteVariables(op, v1, v2, goThroughNts, ctx);
+        for (Mutable<ILogicalOperator> opRef2 : op.getInputs()) {
+            substituteVarRec((AbstractLogicalOperator) opRef2.getValue(), v1, v2, goThroughNts, ctx);
+        }
+        if (op.getOperatorTag() == LogicalOperatorTag.NESTEDTUPLESOURCE && goThroughNts) {
+            NestedTupleSourceOperator nts = (NestedTupleSourceOperator) op;
+            if (nts.getDataSourceReference() != null) {
+                AbstractLogicalOperator op2 = (AbstractLogicalOperator) nts.getDataSourceReference().getValue()
+                        .getInputs().get(0).getValue();
+                substituteVarRec(op2, v1, v2, goThroughNts, ctx);
+            }
+        }
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans aonp = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan p : aonp.getNestedPlans()) {
+                for (Mutable<ILogicalOperator> ref : p.getRoots()) {
+                    AbstractLogicalOperator aop = (AbstractLogicalOperator) ref.getValue();
+                    substituteVarRec(aop, v1, v2, goThroughNts, ctx);
+                }
+            }
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorPropertiesUtil.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorPropertiesUtil.java
new file mode 100644
index 0000000..cd8f042
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/util/OperatorPropertiesUtil.java
@@ -0,0 +1,211 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.util;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalExpressionTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.AlgebricksBuiltinFunctions;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+
+public class OperatorPropertiesUtil {
+
+    public static <T> boolean disjoint(Collection<T> c1, Collection<T> c2) {
+        for (T m : c1) {
+            if (c2.contains(m)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    // Obs: doesn't return expected result for op. with nested plans.
+    private static void getFreeVariablesInOp(ILogicalOperator op, Set<LogicalVariable> freeVars)
+            throws AlgebricksException {
+        VariableUtilities.getUsedVariables(op, freeVars);
+        HashSet<LogicalVariable> produced = new HashSet<LogicalVariable>();
+        VariableUtilities.getProducedVariables(op, produced);
+        for (LogicalVariable v : produced) {
+            freeVars.remove(v);
+        }
+    }
+
+    /**
+     * Adds the free variables of the plan rooted at that operator to the
+     * collection provided.
+     * 
+     * @param op
+     * @param vars
+     *            - The collection to which the free variables will be added.
+     */
+    public static void getFreeVariablesInSelfOrDesc(AbstractLogicalOperator op, Set<LogicalVariable> freeVars)
+            throws AlgebricksException {
+        HashSet<LogicalVariable> produced = new HashSet<LogicalVariable>();
+        VariableUtilities.getProducedVariables(op, produced);
+        for (LogicalVariable v : produced) {
+            freeVars.remove(v);
+        }
+
+        HashSet<LogicalVariable> used = new HashSet<LogicalVariable>();
+        VariableUtilities.getUsedVariables(op, used);
+        for (LogicalVariable v : used) {
+            if (!freeVars.contains(v)) {
+                freeVars.add(v);
+            }
+        }
+
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans s = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan p : s.getNestedPlans()) {
+                for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                    getFreeVariablesInSelfOrDesc((AbstractLogicalOperator) r.getValue(), freeVars);
+                }
+            }
+            s.getUsedVariablesExceptNestedPlans(freeVars);
+            HashSet<LogicalVariable> produced2 = new HashSet<LogicalVariable>();
+            s.getProducedVariablesExceptNestedPlans(produced2);
+            freeVars.removeAll(produced);
+        }
+        for (Mutable<ILogicalOperator> i : op.getInputs()) {
+            getFreeVariablesInSelfOrDesc((AbstractLogicalOperator) i.getValue(), freeVars);
+        }
+    }
+
+    public static void getFreeVariablesInSubplans(AbstractOperatorWithNestedPlans op, Set<LogicalVariable> freeVars)
+            throws AlgebricksException {
+        for (ILogicalPlan p : op.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                getFreeVariablesInSelfOrDesc((AbstractLogicalOperator) r.getValue(), freeVars);
+            }
+        }
+    }
+
+    public static boolean hasFreeVariablesInSelfOrDesc(AbstractLogicalOperator op) throws AlgebricksException {
+        HashSet<LogicalVariable> free = new HashSet<LogicalVariable>();
+        getFreeVariablesInSelfOrDesc(op, free);
+        return !free.isEmpty();
+    }
+
+    public static boolean hasFreeVariables(ILogicalOperator op) throws AlgebricksException {
+        HashSet<LogicalVariable> free = new HashSet<LogicalVariable>();
+        getFreeVariablesInOp(op, free);
+        return !free.isEmpty();
+    }
+
+    public static void computeSchemaAndPropertiesRecIfNull(AbstractLogicalOperator op, IOptimizationContext context)
+            throws AlgebricksException {
+        if (op.getSchema() == null) {
+            for (Mutable<ILogicalOperator> i : op.getInputs()) {
+                computeSchemaAndPropertiesRecIfNull((AbstractLogicalOperator) i.getValue(), context);
+            }
+            if (op.hasNestedPlans()) {
+                AbstractOperatorWithNestedPlans a = (AbstractOperatorWithNestedPlans) op;
+                for (ILogicalPlan p : a.getNestedPlans()) {
+                    for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                        computeSchemaAndPropertiesRecIfNull((AbstractLogicalOperator) r.getValue(), context);
+                    }
+                }
+            }
+            op.recomputeSchema();
+            op.computeDeliveredPhysicalProperties(context);
+        }
+    }
+
+    public static void computeSchemaRecIfNull(AbstractLogicalOperator op) throws AlgebricksException {
+        if (op.getSchema() == null) {
+            for (Mutable<ILogicalOperator> i : op.getInputs()) {
+                computeSchemaRecIfNull((AbstractLogicalOperator) i.getValue());
+            }
+            if (op.hasNestedPlans()) {
+                AbstractOperatorWithNestedPlans a = (AbstractOperatorWithNestedPlans) op;
+                for (ILogicalPlan p : a.getNestedPlans()) {
+                    for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                        computeSchemaRecIfNull((AbstractLogicalOperator) r.getValue());
+                    }
+                }
+            }
+            op.recomputeSchema();
+        }
+    }
+
+    public static boolean isNullTest(AbstractLogicalOperator op) {
+        if (op.getOperatorTag() != LogicalOperatorTag.SELECT) {
+            return false;
+        }
+        AbstractLogicalOperator doubleUnder = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+        if (doubleUnder.getOperatorTag() != LogicalOperatorTag.NESTEDTUPLESOURCE) {
+            return false;
+        }
+        ILogicalExpression eu = ((SelectOperator) op).getCondition().getValue();
+        if (eu.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+            return false;
+        }
+        AbstractFunctionCallExpression f1 = (AbstractFunctionCallExpression) eu;
+        if (!f1.getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.NOT)) {
+            return false;
+        }
+        ILogicalExpression a1 = f1.getArguments().get(0).getValue();
+        if (!a1.getExpressionTag().equals(LogicalExpressionTag.FUNCTION_CALL)) {
+            return false;
+        }
+        AbstractFunctionCallExpression f2 = (AbstractFunctionCallExpression) a1;
+        if (!f2.getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.IS_NULL)) {
+            return false;
+        }
+        return true;
+    }
+
+    public static void typePlan(ILogicalPlan p, IOptimizationContext context) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> r : p.getRoots()) {
+            typeOpRec(r, context);
+        }
+    }
+
+    public static void typeOpRec(Mutable<ILogicalOperator> r, IOptimizationContext context) throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) r.getValue();
+        for (Mutable<ILogicalOperator> i : op.getInputs()) {
+            typeOpRec(i, context);
+        }
+        if (op.hasNestedPlans()) {
+            for (ILogicalPlan p : ((AbstractOperatorWithNestedPlans) op).getNestedPlans()) {
+                typePlan(p, context);
+            }
+        }
+        context.computeAndSetTypeEnvironmentForOperator(op);
+    }
+
+    public static boolean isAlwaysTrueCond(ILogicalExpression cond) {
+        if (cond.getExpressionTag() == LogicalExpressionTag.CONSTANT) {
+            return ((ConstantExpression) cond).getValue().isTrue();
+        }
+        return false;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/AbstractConstVarFunVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/AbstractConstVarFunVisitor.java
new file mode 100644
index 0000000..fac5052
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/AbstractConstVarFunVisitor.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.visitors;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AggregateFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.StatefulFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
+
+public abstract class AbstractConstVarFunVisitor<R, T> implements ILogicalExpressionVisitor<R, T> {
+
+    public abstract R visitFunctionCallExpression(AbstractFunctionCallExpression expr, T arg)
+            throws AlgebricksException;
+
+    public R visitAggregateFunctionCallExpression(AggregateFunctionCallExpression expr, T arg)
+            throws AlgebricksException {
+        return visitFunctionCallExpression(expr, arg);
+    }
+
+    public R visitScalarFunctionCallExpression(ScalarFunctionCallExpression expr, T arg) throws AlgebricksException {
+        return visitFunctionCallExpression(expr, arg);
+    }
+
+    public R visitStatefulFunctionCallExpression(StatefulFunctionCallExpression expr, T arg) throws AlgebricksException {
+        return visitFunctionCallExpression(expr, arg);
+    }
+
+    public R visitUnnestingFunctionCallExpression(UnnestingFunctionCallExpression expr, T arg)
+            throws AlgebricksException {
+        return visitFunctionCallExpression(expr, arg);
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionReferenceTransform.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionReferenceTransform.java
new file mode 100644
index 0000000..a5808b1
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionReferenceTransform.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.visitors;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+
+public interface ILogicalExpressionReferenceTransform {
+    // returns true if any change is made to the expression
+    public boolean transform(Mutable<ILogicalExpression> expression) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionVisitor.java
new file mode 100644
index 0000000..d64b6ae
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalExpressionVisitor.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.visitors;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.AggregateFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ScalarFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.StatefulFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+
+public interface ILogicalExpressionVisitor<R, T> {
+    public R visitConstantExpression(ConstantExpression expr, T arg) throws AlgebricksException;
+
+    public R visitVariableReferenceExpression(VariableReferenceExpression expr, T arg) throws AlgebricksException;
+
+    public R visitAggregateFunctionCallExpression(AggregateFunctionCallExpression expr, T arg)
+            throws AlgebricksException;
+
+    public R visitScalarFunctionCallExpression(ScalarFunctionCallExpression expr, T arg) throws AlgebricksException;
+
+    public R visitStatefulFunctionCallExpression(StatefulFunctionCallExpression expr, T arg) throws AlgebricksException;
+
+    public R visitUnnestingFunctionCallExpression(UnnestingFunctionCallExpression expr, T arg)
+            throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java
new file mode 100644
index 0000000..6b5949e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java
@@ -0,0 +1,107 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.algebra.visitors;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DataSourceScanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DieOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.DistinctOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.EmptyTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExchangeOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IndexInsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InnerJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.InsertDeleteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LeftOuterJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.LimitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.NestedTupleSourceOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.OrderOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.PartitioningSplitOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ReplicateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ScriptOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SinkOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ExtensionOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestMapOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.WriteResultOperator;
+
+public interface ILogicalOperatorVisitor<R, T> {
+
+    public R visitAggregateOperator(AggregateOperator op, T arg) throws AlgebricksException;
+
+    public R visitRunningAggregateOperator(RunningAggregateOperator op, T arg) throws AlgebricksException;
+
+    public R visitEmptyTupleSourceOperator(EmptyTupleSourceOperator op, T arg) throws AlgebricksException;
+
+    public R visitGroupByOperator(GroupByOperator op, T arg) throws AlgebricksException;
+
+    public R visitLimitOperator(LimitOperator op, T arg) throws AlgebricksException;
+
+    public R visitInnerJoinOperator(InnerJoinOperator op, T arg) throws AlgebricksException;
+
+    public R visitLeftOuterJoinOperator(LeftOuterJoinOperator op, T arg) throws AlgebricksException;
+
+    public R visitNestedTupleSourceOperator(NestedTupleSourceOperator op, T arg) throws AlgebricksException;
+
+    public R visitOrderOperator(OrderOperator op, T arg) throws AlgebricksException;
+
+    public R visitAssignOperator(AssignOperator op, T arg) throws AlgebricksException;
+
+    public R visitSelectOperator(SelectOperator op, T arg) throws AlgebricksException;
+
+    public R visitExtensionOperator(ExtensionOperator op, T arg) throws AlgebricksException;
+
+    public R visitProjectOperator(ProjectOperator op, T arg) throws AlgebricksException;
+
+    public R visitPartitioningSplitOperator(PartitioningSplitOperator op, T arg) throws AlgebricksException;
+
+    public R visitReplicateOperator(ReplicateOperator op, T arg) throws AlgebricksException;
+
+    public R visitScriptOperator(ScriptOperator op, T arg) throws AlgebricksException;
+
+    public R visitSubplanOperator(SubplanOperator op, T arg) throws AlgebricksException;
+
+    public R visitSinkOperator(SinkOperator op, T arg) throws AlgebricksException;
+
+    public R visitUnionOperator(UnionAllOperator op, T arg) throws AlgebricksException;
+
+    public R visitUnnestOperator(UnnestOperator op, T arg) throws AlgebricksException;
+
+    public R visitUnnestMapOperator(UnnestMapOperator op, T arg) throws AlgebricksException;
+
+    public R visitDataScanOperator(DataSourceScanOperator op, T arg) throws AlgebricksException;
+
+    public R visitDistinctOperator(DistinctOperator op, T arg) throws AlgebricksException;
+
+    public R visitExchangeOperator(ExchangeOperator op, T arg) throws AlgebricksException;
+
+    public R visitWriteOperator(WriteOperator op, T arg) throws AlgebricksException;
+
+    public R visitWriteResultOperator(WriteResultOperator op, T arg) throws AlgebricksException;
+
+    public R visitInsertDeleteOperator(InsertDeleteOperator op, T tag) throws AlgebricksException;
+
+    public R visitIndexInsertDeleteOperator(IndexInsertDeleteOperator op, T tag) throws AlgebricksException;
+
+    public R visitDieOperator(DieOperator op, T arg) throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/AlgebricksConfig.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/AlgebricksConfig.java
new file mode 100644
index 0000000..11ec043
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/AlgebricksConfig.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.config;
+
+import java.util.logging.Logger;
+
+public class AlgebricksConfig {
+    public static final boolean DEBUG = true;
+    public static final String ALGEBRICKS_LOGGER_NAME = "edu.uci.ics.hyracks.algebricks";
+    public static final Logger ALGEBRICKS_LOGGER = Logger.getLogger(ALGEBRICKS_LOGGER_NAME);
+    public static final String HYRACKS_APP_NAME = "algebricks";
+
+    // public static final Level ALGEBRICKS_LOG_LEVEL = Level.FINEST;
+    //
+    // static {
+    // Handler h;
+    // try {
+    // h = new ConsoleHandler();
+    // h.setFormatter(new SysoutFormatter());
+    // } catch (Exception e) {
+    // h = new ConsoleHandler();
+    // }
+    // h.setLevel(ALGEBRICKS_LOG_LEVEL);
+    // ALGEBRICKS_LOGGER.addHandler(h);
+    // ALGEBRICKS_LOGGER.setLevel(ALGEBRICKS_LOG_LEVEL);
+    // }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/SysoutFormatter.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/SysoutFormatter.java
new file mode 100644
index 0000000..872676b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/config/SysoutFormatter.java
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.config;
+
+import java.util.logging.Formatter;
+import java.util.logging.Handler;
+import java.util.logging.LogRecord;
+
+public class SysoutFormatter extends Formatter {
+    public String format(LogRecord rec) {
+        StringBuffer buf = new StringBuffer(5000);
+        buf.append(formatMessage(rec));
+        return buf.toString();
+    }
+
+    public String getHead(Handler h) {
+        return "";
+    }
+
+    public String getTail(Handler h) {
+        return "";
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/ConnectorPolicyAssignmentPolicy.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/ConnectorPolicyAssignmentPolicy.java
new file mode 100644
index 0000000..e786f8c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/ConnectorPolicyAssignmentPolicy.java
@@ -0,0 +1,24 @@
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.connectors.IConnectorPolicy;
+import edu.uci.ics.hyracks.api.dataflow.connectors.IConnectorPolicyAssignmentPolicy;
+import edu.uci.ics.hyracks.api.dataflow.connectors.PipeliningConnectorPolicy;
+import edu.uci.ics.hyracks.api.dataflow.connectors.SendSideMaterializedPipeliningConnectorPolicy;
+import edu.uci.ics.hyracks.dataflow.std.connectors.MToNPartitioningMergingConnectorDescriptor;
+
+public class ConnectorPolicyAssignmentPolicy implements IConnectorPolicyAssignmentPolicy {
+    private static final long serialVersionUID = 1L;
+    private IConnectorPolicy senderSideMaterializePolicy = new SendSideMaterializedPipeliningConnectorPolicy();
+    private IConnectorPolicy pipeliningPolicy = new PipeliningConnectorPolicy();
+
+    @Override
+    public IConnectorPolicy getConnectorPolicyAssignment(IConnectorDescriptor c, int nProducers, int nConsumers,
+            int[] fanouts) {
+        if (c instanceof MToNPartitioningMergingConnectorDescriptor) {
+            return senderSideMaterializePolicy;
+        } else {
+            return pipeliningPolicy;
+        }
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobBuilder.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobBuilder.java
new file mode 100644
index 0000000..61625d3
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobBuilder.java
@@ -0,0 +1,323 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksCountPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraintHelper;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.runtime.base.IPushRuntimeFactory;
+import edu.uci.ics.hyracks.algebricks.runtime.operators.meta.AlgebricksMetaOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.ConnectorDescriptorId;
+import edu.uci.ics.hyracks.api.dataflow.IConnectorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.OperatorDescriptorId;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public class JobBuilder implements IHyracksJobBuilder {
+
+    private JobSpecification jobSpec;
+    private AlgebricksPartitionConstraint clusterLocations;
+
+    private Map<ILogicalOperator, ArrayList<ILogicalOperator>> outEdges = new HashMap<ILogicalOperator, ArrayList<ILogicalOperator>>();
+    private Map<ILogicalOperator, ArrayList<ILogicalOperator>> inEdges = new HashMap<ILogicalOperator, ArrayList<ILogicalOperator>>();
+    private Map<ILogicalOperator, Pair<IConnectorDescriptor, TargetConstraint>> connectors = new HashMap<ILogicalOperator, Pair<IConnectorDescriptor, TargetConstraint>>();
+
+    private Map<ILogicalOperator, Pair<IPushRuntimeFactory, RecordDescriptor>> microOps = new HashMap<ILogicalOperator, Pair<IPushRuntimeFactory, RecordDescriptor>>();
+    private Map<IPushRuntimeFactory, ILogicalOperator> revMicroOpMap = new HashMap<IPushRuntimeFactory, ILogicalOperator>();
+    private Map<ILogicalOperator, IOperatorDescriptor> hyracksOps = new HashMap<ILogicalOperator, IOperatorDescriptor>();
+    private Map<ILogicalOperator, AlgebricksPartitionConstraint> pcForMicroOps = new HashMap<ILogicalOperator, AlgebricksPartitionConstraint>();
+
+    private int aodCounter = 0;
+    private Map<ILogicalOperator, Integer> algebraicOpBelongingToMetaAsterixOp = new HashMap<ILogicalOperator, Integer>();
+    private Map<Integer, List<Pair<IPushRuntimeFactory, RecordDescriptor>>> metaAsterixOpSkeletons = new HashMap<Integer, List<Pair<IPushRuntimeFactory, RecordDescriptor>>>();
+    private Map<Integer, AlgebricksMetaOperatorDescriptor> metaAsterixOps = new HashMap<Integer, AlgebricksMetaOperatorDescriptor>();
+    private final Map<IOperatorDescriptor, AlgebricksPartitionConstraint> partitionConstraintMap = new HashMap<IOperatorDescriptor, AlgebricksPartitionConstraint>();
+
+    public JobBuilder(JobSpecification jobSpec, AlgebricksPartitionConstraint clusterLocations) {
+        this.jobSpec = jobSpec;
+        this.clusterLocations = clusterLocations;
+    }
+
+    @Override
+    public void contributeMicroOperator(ILogicalOperator op, IPushRuntimeFactory runtime, RecordDescriptor recDesc) {
+        contributeMicroOperator(op, runtime, recDesc, null);
+    }
+
+    @Override
+    public void contributeMicroOperator(ILogicalOperator op, IPushRuntimeFactory runtime, RecordDescriptor recDesc,
+            AlgebricksPartitionConstraint pc) {
+        microOps.put(op, new Pair<IPushRuntimeFactory, RecordDescriptor>(runtime, recDesc));
+        revMicroOpMap.put(runtime, op);
+        if (pc != null) {
+            pcForMicroOps.put(op, pc);
+        }
+    }
+
+    @Override
+    public void contributeConnector(ILogicalOperator exchgOp, IConnectorDescriptor conn) {
+        connectors.put(exchgOp, new Pair<IConnectorDescriptor, TargetConstraint>(conn, null));
+    }
+
+    @Override
+    public void contributeConnectorWithTargetConstraint(ILogicalOperator exchgOp, IConnectorDescriptor conn,
+            TargetConstraint numberOfTargetPartitions) {
+        connectors.put(exchgOp, new Pair<IConnectorDescriptor, TargetConstraint>(conn, numberOfTargetPartitions));
+    }
+
+    @Override
+    public void contributeGraphEdge(ILogicalOperator src, int srcOutputIndex, ILogicalOperator dest, int destInputIndex) {
+        ArrayList<ILogicalOperator> outputs = outEdges.get(src);
+        if (outputs == null) {
+            outputs = new ArrayList<ILogicalOperator>();
+            outEdges.put(src, outputs);
+        }
+        addAtPos(outputs, dest, srcOutputIndex);
+
+        ArrayList<ILogicalOperator> inp = inEdges.get(dest);
+        if (inp == null) {
+            inp = new ArrayList<ILogicalOperator>();
+            inEdges.put(dest, inp);
+        }
+        addAtPos(inp, src, destInputIndex);
+    }
+
+    @Override
+    public void contributeHyracksOperator(ILogicalOperator op, IOperatorDescriptor opDesc) {
+        hyracksOps.put(op, opDesc);
+    }
+
+    @Override
+    public void contributeAlgebricksPartitionConstraint(IOperatorDescriptor opDesc, AlgebricksPartitionConstraint apc) {
+        partitionConstraintMap.put(opDesc, apc);
+    }
+
+    @Override
+    public JobSpecification getJobSpec() {
+        return jobSpec;
+    }
+
+    @Override
+    public void buildSpec(List<ILogicalOperator> roots) throws AlgebricksException {
+        buildAsterixComponents();
+        Map<IConnectorDescriptor, TargetConstraint> tgtConstraints = setupConnectors();
+        for (ILogicalOperator r : roots) {
+            IOperatorDescriptor opDesc = findOpDescForAlgebraicOp(r);
+            jobSpec.addRoot(opDesc);
+        }
+        setAllPartitionConstraints(tgtConstraints);
+    }
+
+    private void setAllPartitionConstraints(Map<IConnectorDescriptor, TargetConstraint> tgtConstraints) {
+        List<OperatorDescriptorId> roots = jobSpec.getRoots();
+        setSpecifiedPartitionConstraints();
+        for (OperatorDescriptorId rootId : roots) {
+            setPartitionConstraintsDFS(rootId, tgtConstraints, null);
+        }
+    }
+
+    private void setSpecifiedPartitionConstraints() {
+        for (ILogicalOperator op : pcForMicroOps.keySet()) {
+            AlgebricksPartitionConstraint pc = pcForMicroOps.get(op);
+            Integer k = algebraicOpBelongingToMetaAsterixOp.get(op);
+            AlgebricksMetaOperatorDescriptor amod = metaAsterixOps.get(k);
+            partitionConstraintMap.put(amod, pc);
+        }
+        for (IOperatorDescriptor opDesc : partitionConstraintMap.keySet()) {
+            AlgebricksPartitionConstraint pc = partitionConstraintMap.get(opDesc);
+            AlgebricksPartitionConstraintHelper.setPartitionConstraintInJobSpec(jobSpec, opDesc, pc);
+        }
+    }
+
+    private void setPartitionConstraintsDFS(OperatorDescriptorId opId,
+            Map<IConnectorDescriptor, TargetConstraint> tgtConstraints, IOperatorDescriptor parentOp) {
+        List<IConnectorDescriptor> opInputs = jobSpec.getOperatorInputMap().get(opId);
+        AlgebricksPartitionConstraint opConstraint = null;
+        IOperatorDescriptor opDesc = jobSpec.getOperatorMap().get(opId);
+        if (opInputs != null) {
+            for (IConnectorDescriptor conn : opInputs) {
+                ConnectorDescriptorId cid = conn.getConnectorId();
+                org.apache.commons.lang3.tuple.Pair<org.apache.commons.lang3.tuple.Pair<IOperatorDescriptor, Integer>, org.apache.commons.lang3.tuple.Pair<IOperatorDescriptor, Integer>> p = jobSpec
+                        .getConnectorOperatorMap().get(cid);
+                IOperatorDescriptor src = p.getLeft().getLeft();
+                // DFS
+                setPartitionConstraintsDFS(src.getOperatorId(), tgtConstraints, opDesc);
+
+                TargetConstraint constraint = tgtConstraints.get(conn);
+                if (constraint != null) {
+                    switch (constraint) {
+                        case ONE: {
+                            opConstraint = new AlgebricksCountPartitionConstraint(1);
+                            break;
+                        }
+                        case SAME_COUNT: {
+                            opConstraint = partitionConstraintMap.get(src);
+                            break;
+                        }
+                    }
+                }
+            }
+        }
+        if (partitionConstraintMap.get(opDesc) == null) {
+            if (opConstraint == null) {
+                if (parentOp != null) {
+                    AlgebricksPartitionConstraint pc = partitionConstraintMap.get(parentOp);
+                    if (pc != null) {
+                        opConstraint = pc;
+                    } else if (opInputs == null || opInputs.size() == 0) {
+                        opConstraint = new AlgebricksCountPartitionConstraint(1);
+                    }
+                }
+                if (opConstraint == null) {
+                    opConstraint = clusterLocations;
+                }
+            }
+            partitionConstraintMap.put(opDesc, opConstraint);
+            AlgebricksPartitionConstraintHelper.setPartitionConstraintInJobSpec(jobSpec, opDesc, opConstraint);
+        }
+    }
+
+    private Map<IConnectorDescriptor, TargetConstraint> setupConnectors() throws AlgebricksException {
+        Map<IConnectorDescriptor, TargetConstraint> tgtConstraints = new HashMap<IConnectorDescriptor, TargetConstraint>();
+        for (ILogicalOperator exchg : connectors.keySet()) {
+            ILogicalOperator inOp = inEdges.get(exchg).get(0);
+            ILogicalOperator outOp = outEdges.get(exchg).get(0);
+            IOperatorDescriptor inOpDesc = findOpDescForAlgebraicOp(inOp);
+            IOperatorDescriptor outOpDesc = findOpDescForAlgebraicOp(outOp);
+            Pair<IConnectorDescriptor, TargetConstraint> connPair = connectors.get(exchg);
+            IConnectorDescriptor conn = connPair.first;
+            int producerPort = outEdges.get(inOp).indexOf(exchg);
+            int consumerPort = inEdges.get(outOp).indexOf(exchg);
+            jobSpec.connect(conn, inOpDesc, producerPort, outOpDesc, consumerPort);
+            if (connPair.second != null) {
+                tgtConstraints.put(conn, connPair.second);
+            }
+        }
+        return tgtConstraints;
+    }
+
+    private IOperatorDescriptor findOpDescForAlgebraicOp(ILogicalOperator op) throws AlgebricksException {
+        IOperatorDescriptor hOpDesc = hyracksOps.get(op);
+        if (hOpDesc != null) {
+            return hOpDesc;
+        }
+        Integer metaOpKey = algebraicOpBelongingToMetaAsterixOp.get(op);
+        if (metaOpKey == null) {
+            throw new AlgebricksException("Could not generate operator descriptor for operator " + op);
+        }
+        return metaAsterixOps.get(metaOpKey);
+    }
+
+    private void buildAsterixComponents() {
+        for (ILogicalOperator aop : microOps.keySet()) {
+            addMicroOpToMetaRuntimeOp(aop);
+        }
+        for (Integer k : metaAsterixOpSkeletons.keySet()) {
+            List<Pair<IPushRuntimeFactory, RecordDescriptor>> opContents = metaAsterixOpSkeletons.get(k);
+            AlgebricksMetaOperatorDescriptor amod = buildMetaAsterixOpDesc(opContents);
+            metaAsterixOps.put(k, amod);
+        }
+    }
+
+    private AlgebricksMetaOperatorDescriptor buildMetaAsterixOpDesc(
+            List<Pair<IPushRuntimeFactory, RecordDescriptor>> opContents) {
+        // RecordDescriptor outputRecordDesc = null;
+        int n = opContents.size();
+        IPushRuntimeFactory[] runtimeFactories = new IPushRuntimeFactory[n];
+        RecordDescriptor[] internalRecordDescriptors = new RecordDescriptor[n];
+        int i = 0;
+        for (Pair<IPushRuntimeFactory, RecordDescriptor> p : opContents) {
+            runtimeFactories[i] = p.first;
+            internalRecordDescriptors[i] = p.second;
+            // if (i == n - 1) {
+            // outputRecordDesc = p.second;
+            // }
+            i++;
+        }
+        ILogicalOperator lastLogicalOp = revMicroOpMap.get(runtimeFactories[n - 1]);
+        ArrayList<ILogicalOperator> outOps = outEdges.get(lastLogicalOp);
+        int outArity = (outOps == null) ? 0 : outOps.size();
+        ILogicalOperator firstLogicalOp = revMicroOpMap.get(runtimeFactories[0]);
+        ArrayList<ILogicalOperator> inOps = inEdges.get(firstLogicalOp);
+        int inArity = (inOps == null) ? 0 : inOps.size();
+        // boolean isLeafOp = inEdges.get(firstLogicalOp) == null;
+        return new AlgebricksMetaOperatorDescriptor(jobSpec, inArity, outArity, runtimeFactories,
+                internalRecordDescriptors);
+    }
+
+    private void addMicroOpToMetaRuntimeOp(ILogicalOperator aop) {
+        Integer k = algebraicOpBelongingToMetaAsterixOp.get(aop);
+        if (k == null) {
+            k = createNewMetaOpInfo(aop);
+        }
+        ArrayList<ILogicalOperator> destList = outEdges.get(aop);
+        if (destList == null || destList.size() != 1) {
+            // for now, we only support linear plans inside meta-ops.
+            return;
+        }
+        ILogicalOperator dest = destList.get(0);
+        Integer j = algebraicOpBelongingToMetaAsterixOp.get(dest);
+        if (j == null && microOps.get(dest) != null) {
+            algebraicOpBelongingToMetaAsterixOp.put(dest, k);
+            List<Pair<IPushRuntimeFactory, RecordDescriptor>> aodContent1 = metaAsterixOpSkeletons.get(k);
+            aodContent1.add(microOps.get(dest));
+        } else if (j != null && j.intValue() != k.intValue()) {
+            // merge the j component into the k component
+            List<Pair<IPushRuntimeFactory, RecordDescriptor>> aodContent1 = metaAsterixOpSkeletons.get(k);
+            List<Pair<IPushRuntimeFactory, RecordDescriptor>> aodContent2 = metaAsterixOpSkeletons.get(j);
+            aodContent1.addAll(aodContent2);
+            metaAsterixOpSkeletons.remove(j);
+            for (ILogicalOperator m : algebraicOpBelongingToMetaAsterixOp.keySet()) {
+                Integer g = algebraicOpBelongingToMetaAsterixOp.get(m);
+                if (g.intValue() == j.intValue()) {
+                    algebraicOpBelongingToMetaAsterixOp.put(m, k);
+                }
+            }
+        }
+
+    }
+
+    private int createNewMetaOpInfo(ILogicalOperator aop) {
+        int n = aodCounter;
+        aodCounter++;
+        List<Pair<IPushRuntimeFactory, RecordDescriptor>> metaOpContents = new ArrayList<Pair<IPushRuntimeFactory, RecordDescriptor>>();
+        metaOpContents.add(microOps.get(aop));
+        metaAsterixOpSkeletons.put(n, metaOpContents);
+        algebraicOpBelongingToMetaAsterixOp.put(aop, n);
+        return n;
+    }
+
+    private <E> void addAtPos(ArrayList<E> a, E elem, int pos) {
+        int n = a.size();
+        if (n > pos) {
+            a.set(pos, elem);
+        } else {
+            for (int k = n; k < pos; k++) {
+                a.add(null);
+            }
+            a.add(elem);
+        }
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
new file mode 100644
index 0000000..22a1a81
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
@@ -0,0 +1,192 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.constraints.AlgebricksPartitionConstraint;
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionEvalSizeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionRuntimeProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IPartialAggregationTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.core.algebra.typing.ITypingContext;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryBooleanInspectorFactory;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryIntegerInspectorFactory;
+import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.ISerializerDeserializerProvider;
+import edu.uci.ics.hyracks.algebricks.data.ITypeTraitProvider;
+import edu.uci.ics.hyracks.api.dataflow.value.INullWriterFactory;
+
+public class JobGenContext {
+    private final IOperatorSchema outerFlowSchema;
+    private final Map<ILogicalOperator, IOperatorSchema> schemaMap = new HashMap<ILogicalOperator, IOperatorSchema>();
+    private final ISerializerDeserializerProvider serializerDeserializerProvider;
+    private final IBinaryHashFunctionFactoryProvider hashFunctionFactoryProvider;
+    private final IBinaryComparatorFactoryProvider comparatorFactoryProvider;
+    private final IPrinterFactoryProvider printerFactoryProvider;
+    private final ITypeTraitProvider typeTraitProvider;
+    private final IMetadataProvider<?, ?> metadataProvider;
+    private final INullWriterFactory nullWriterFactory;
+    private final INormalizedKeyComputerFactoryProvider normalizedKeyComputerFactoryProvider;
+    private final Object appContext;
+    private final IBinaryBooleanInspectorFactory booleanInspectorFactory;
+    private final IBinaryIntegerInspectorFactory integerInspectorFactory;
+    private final IExpressionRuntimeProvider expressionRuntimeProvider;
+    private final IExpressionTypeComputer expressionTypeComputer;
+    private final IExpressionEvalSizeComputer expressionEvalSizeComputer;
+    private final IPartialAggregationTypeComputer partialAggregationTypeComputer;
+    private final int frameSize;
+    private AlgebricksPartitionConstraint clusterLocations;
+    private int varCounter;
+    private final ITypingContext typingContext;
+
+    public JobGenContext(IOperatorSchema outerFlowSchema, IMetadataProvider<?, ?> metadataProvider, Object appContext,
+            ISerializerDeserializerProvider serializerDeserializerProvider,
+            IBinaryHashFunctionFactoryProvider hashFunctionFactoryProvider,
+            IBinaryComparatorFactoryProvider comparatorFactoryProvider, ITypeTraitProvider typeTraitProvider,
+            IBinaryBooleanInspectorFactory booleanInspectorFactory,
+            IBinaryIntegerInspectorFactory integerInspectorFactory, IPrinterFactoryProvider printerFactoryProvider,
+            INullWriterFactory nullWriterFactory,
+            INormalizedKeyComputerFactoryProvider normalizedKeyComputerFactoryProvider,
+            IExpressionRuntimeProvider expressionRuntimeProvider, IExpressionTypeComputer expressionTypeComputer,
+            INullableTypeComputer nullableTypeComputer, ITypingContext typingContext,
+            IExpressionEvalSizeComputer expressionEvalSizeComputer,
+            IPartialAggregationTypeComputer partialAggregationTypeComputer, int frameSize,
+            AlgebricksPartitionConstraint clusterLocations) {
+        this.outerFlowSchema = outerFlowSchema;
+        this.metadataProvider = metadataProvider;
+        this.appContext = appContext;
+        this.serializerDeserializerProvider = serializerDeserializerProvider;
+        this.hashFunctionFactoryProvider = hashFunctionFactoryProvider;
+        this.comparatorFactoryProvider = comparatorFactoryProvider;
+        this.typeTraitProvider = typeTraitProvider;
+        this.booleanInspectorFactory = booleanInspectorFactory;
+        this.integerInspectorFactory = integerInspectorFactory;
+        this.printerFactoryProvider = printerFactoryProvider;
+        this.clusterLocations = clusterLocations;
+        this.normalizedKeyComputerFactoryProvider = normalizedKeyComputerFactoryProvider;
+        this.nullWriterFactory = nullWriterFactory;
+        this.expressionRuntimeProvider = expressionRuntimeProvider;
+        this.expressionTypeComputer = expressionTypeComputer;
+        this.typingContext = typingContext;
+        this.expressionEvalSizeComputer = expressionEvalSizeComputer;
+        this.partialAggregationTypeComputer = partialAggregationTypeComputer;
+        this.frameSize = frameSize;
+        this.varCounter = 0;
+    }
+
+    public IOperatorSchema getOuterFlowSchema() {
+        return outerFlowSchema;
+    }
+
+    public AlgebricksPartitionConstraint getClusterLocations() {
+        return clusterLocations;
+    }
+
+    public IMetadataProvider<?, ?> getMetadataProvider() {
+        return metadataProvider;
+    }
+
+    public Object getAppContext() {
+        return appContext;
+    }
+
+    public ISerializerDeserializerProvider getSerializerDeserializerProvider() {
+        return serializerDeserializerProvider;
+    }
+
+    public IBinaryHashFunctionFactoryProvider getBinaryHashFunctionFactoryProvider() {
+        return hashFunctionFactoryProvider;
+    }
+
+    public IBinaryComparatorFactoryProvider getBinaryComparatorFactoryProvider() {
+        return comparatorFactoryProvider;
+    }
+
+    public ITypeTraitProvider getTypeTraitProvider() {
+        return typeTraitProvider;
+    }
+
+    public IBinaryBooleanInspectorFactory getBinaryBooleanInspectorFactory() {
+        return booleanInspectorFactory;
+    }
+
+    public IBinaryIntegerInspectorFactory getBinaryIntegerInspectorFactory() {
+        return integerInspectorFactory;
+    }
+
+    public IPrinterFactoryProvider getPrinterFactoryProvider() {
+        return printerFactoryProvider;
+    }
+
+    public IExpressionRuntimeProvider getExpressionRuntimeProvider() {
+        return expressionRuntimeProvider;
+    }
+
+    public IOperatorSchema getSchema(ILogicalOperator op) {
+        return schemaMap.get(op);
+    }
+
+    public void putSchema(ILogicalOperator op, IOperatorSchema schema) {
+        schemaMap.put(op, schema);
+    }
+
+    public LogicalVariable createNewVar() {
+        varCounter++;
+        LogicalVariable var = new LogicalVariable(-varCounter);
+        return var;
+    }
+
+    public Object getType(ILogicalExpression expr, IVariableTypeEnvironment env) throws AlgebricksException {
+        return expressionTypeComputer.getType(expr, typingContext.getMetadataProvider(), env);
+    }
+
+    public INullWriterFactory getNullWriterFactory() {
+        return nullWriterFactory;
+    }
+
+    public INormalizedKeyComputerFactoryProvider getNormalizedKeyComputerFactoryProvider() {
+        return normalizedKeyComputerFactoryProvider;
+    }
+
+    public IExpressionEvalSizeComputer getExpressionEvalSizeComputer() {
+        return expressionEvalSizeComputer;
+    }
+
+    public int getFrameSize() {
+        return frameSize;
+    }
+
+    public IPartialAggregationTypeComputer getPartialAggregationTypeComputer() {
+        return partialAggregationTypeComputer;
+    }
+
+    public IVariableTypeEnvironment getTypeEnvironment(ILogicalOperator op) {
+        return typingContext.getOutputTypeEnvironment(op);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java
new file mode 100644
index 0000000..790fb93
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java
@@ -0,0 +1,169 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.logging.Logger;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryComparatorFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IBinaryHashFunctionFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactoryProvider;
+import edu.uci.ics.hyracks.algebricks.data.ISerializerDeserializerProvider;
+import edu.uci.ics.hyracks.algebricks.data.ITypeTraitProvider;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryComparatorFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.INormalizedKeyComputerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
+import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+
+public final class JobGenHelper {
+
+    private static final Logger LOGGER = Logger.getLogger(JobGenHelper.class.getName());
+
+    @SuppressWarnings("rawtypes")
+    public static RecordDescriptor mkRecordDescriptor(IVariableTypeEnvironment env, IOperatorSchema opSchema,
+            JobGenContext context) throws AlgebricksException {        
+		ISerializerDeserializer[] fields = new ISerializerDeserializer[opSchema.getSize()];
+        ITypeTraits[] typeTraits = new ITypeTraits[opSchema.getSize()];
+        ISerializerDeserializerProvider sdp = context.getSerializerDeserializerProvider();
+        ITypeTraitProvider ttp = context.getTypeTraitProvider();
+        int i = 0;
+        for (LogicalVariable var : opSchema) {
+            Object t = env.getVarType(var);
+            if (t == null) {
+                LOGGER.warning("No type for variable " + var);
+            }
+            fields[i] = sdp.getSerializerDeserializer(t);
+            typeTraits[i] = ttp.getTypeTrait(t);
+            i++;
+        }
+        return new RecordDescriptor(fields, typeTraits);
+    }
+    
+    public static IPrinterFactory[] mkPrinterFactories(IOperatorSchema opSchema, IVariableTypeEnvironment env,
+            JobGenContext context, int[] printColumns) throws AlgebricksException {
+        IPrinterFactory[] pf = new IPrinterFactory[printColumns.length];
+        IPrinterFactoryProvider pff = context.getPrinterFactoryProvider();
+        for (int i = 0; i < pf.length; i++) {
+            LogicalVariable v = opSchema.getVariable(printColumns[i]);
+            Object t = env.getVarType(v);
+            pf[i] = pff.getPrinterFactory(t);
+        }
+        return pf;
+    }
+
+    public static int[] variablesToFieldIndexes(Collection<LogicalVariable> varLogical, IOperatorSchema opSchema) {
+        int[] tuplePos = new int[varLogical.size()];
+        int i = 0;
+        for (LogicalVariable var : varLogical) {
+            tuplePos[i] = opSchema.findVariable(var);
+            i++;
+        }
+        return tuplePos;
+    }
+
+    public static IBinaryHashFunctionFactory[] variablesToBinaryHashFunctionFactories(
+            Collection<LogicalVariable> varLogical, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        IBinaryHashFunctionFactory[] funFactories = new IBinaryHashFunctionFactory[varLogical.size()];
+        int i = 0;
+        IBinaryHashFunctionFactoryProvider bhffProvider = context.getBinaryHashFunctionFactoryProvider();
+        for (LogicalVariable var : varLogical) {
+            Object type = env.getVarType(var);
+            funFactories[i++] = bhffProvider.getBinaryHashFunctionFactory(type);
+        }
+        return funFactories;
+    }
+    
+    public static IBinaryComparatorFactory[] variablesToAscBinaryComparatorFactories(
+            Collection<LogicalVariable> varLogical, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        IBinaryComparatorFactory[] compFactories = new IBinaryComparatorFactory[varLogical.size()];
+        IBinaryComparatorFactoryProvider bcfProvider = context.getBinaryComparatorFactoryProvider();
+        int i = 0;
+        for (LogicalVariable v : varLogical) {
+            Object type = env.getVarType(v);
+            compFactories[i++] = bcfProvider.getBinaryComparatorFactory(type, true);
+        }
+        return compFactories;
+    }
+    
+    public static IBinaryComparatorFactory[] variablesToAscBinaryComparatorFactories(
+            List<LogicalVariable> varLogical, int start, int size, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        IBinaryComparatorFactory[] compFactories = new IBinaryComparatorFactory[size];
+        IBinaryComparatorFactoryProvider bcfProvider = context.getBinaryComparatorFactoryProvider();
+        for (int i = 0; i < size; i++) {
+                Object type = env.getVarType(varLogical.get(start + i));
+                compFactories[i] = bcfProvider.getBinaryComparatorFactory(type, true);
+        }
+        return compFactories;
+    }
+
+    public static INormalizedKeyComputerFactory variablesToAscNormalizedKeyComputerFactory(
+            Collection<LogicalVariable> varLogical, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        INormalizedKeyComputerFactoryProvider nkcfProvider = context.getNormalizedKeyComputerFactoryProvider();
+        if (nkcfProvider == null)
+            return null;
+        for (LogicalVariable v : varLogical) {
+            Object type = env.getVarType(v);
+            return nkcfProvider.getNormalizedKeyComputerFactory(type, true);
+        }
+        return null;
+    }
+
+    public static ITypeTraits[] variablesToTypeTraits(Collection<LogicalVariable> varLogical,
+            IVariableTypeEnvironment env, JobGenContext context) throws AlgebricksException {
+        ITypeTraits[] typeTraits = new ITypeTraits[varLogical.size()];
+        ITypeTraitProvider typeTraitProvider = context.getTypeTraitProvider();
+        int i = 0;
+        for (LogicalVariable v : varLogical) {
+            Object type = env.getVarType(v);
+            typeTraits[i++] = typeTraitProvider.getTypeTrait(type);
+        }
+        return typeTraits;
+    }
+    
+    public static ITypeTraits[] variablesToTypeTraits(
+            List<LogicalVariable> varLogical, int start, int size, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        ITypeTraits[] typeTraits = new ITypeTraits[size];
+        ITypeTraitProvider typeTraitProvider = context.getTypeTraitProvider();
+        for (int i = 0; i < size; i++) {
+                Object type = env.getVarType(varLogical.get(start + i));
+                typeTraits[i] = typeTraitProvider.getTypeTrait(type);
+        }
+        return typeTraits;
+    }
+
+    public static int[] projectAllVariables(IOperatorSchema opSchema) {
+        int[] projectionList = new int[opSchema.getSize()];
+        int k = 0;
+        for (LogicalVariable v : opSchema) {
+            projectionList[k++] = opSchema.findVariable(v);
+        }
+        return projectionList;
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/OperatorSchemaImpl.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/OperatorSchemaImpl.java
new file mode 100644
index 0000000..d8fc436
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/OperatorSchemaImpl.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+
+public class OperatorSchemaImpl implements IOperatorSchema {
+    private final Map<LogicalVariable, Integer> varMap;
+
+    private final List<LogicalVariable> varList;
+
+    public OperatorSchemaImpl() {
+        varMap = new HashMap<LogicalVariable, Integer>();
+        varList = new ArrayList<LogicalVariable>();
+    }
+
+    @Override
+    public void addAllVariables(IOperatorSchema source) {
+        for (LogicalVariable v : source) {
+            varMap.put(v, varList.size());
+            varList.add(v);
+        }
+    }
+
+    @Override
+    public void addAllNewVariables(IOperatorSchema source) {
+        for (LogicalVariable v : source) {
+            if (varMap.get(v) == null) {
+                varMap.put(v, varList.size());
+                varList.add(v);
+            }
+        }
+    }
+
+    @Override
+    public int addVariable(LogicalVariable var) {
+        int idx = varList.size();
+        varMap.put(var, idx);
+        varList.add(var);
+        return idx;
+    }
+
+    @Override
+    public void clear() {
+        varMap.clear();
+        varList.clear();
+    }
+
+    @Override
+    public int findVariable(LogicalVariable var) {
+        Integer i = varMap.get(var);
+        if (i == null) {
+            return -1;
+        }
+        return i;
+    }
+
+    @Override
+    public int getSize() {
+        return varList.size();
+    }
+
+    @Override
+    public LogicalVariable getVariable(int index) {
+        return varList.get(index);
+    }
+
+    @Override
+    public Iterator<LogicalVariable> iterator() {
+        return varList.iterator();
+    }
+
+    @Override
+    public String toString() {
+        return varMap.toString();
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java
new file mode 100644
index 0000000..bbe8fb3
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.jobgen.impl;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IHyracksJobBuilder;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+import edu.uci.ics.hyracks.api.job.IOperatorDescriptorRegistry;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public class PlanCompiler {
+    private JobGenContext context;
+    private Map<Mutable<ILogicalOperator>, List<Mutable<ILogicalOperator>>> operatorVisitedToParents = new HashMap<Mutable<ILogicalOperator>, List<Mutable<ILogicalOperator>>>();
+
+    public PlanCompiler(JobGenContext context) {
+        this.context = context;
+    }
+
+    public JobGenContext getContext() {
+        return context;
+    }
+
+    public JobSpecification compilePlan(ILogicalPlan plan, IOperatorSchema outerPlanSchema) throws AlgebricksException {
+        JobSpecification spec = new JobSpecification();
+        List<ILogicalOperator> rootOps = new ArrayList<ILogicalOperator>();
+        IHyracksJobBuilder builder = new JobBuilder(spec, context.getClusterLocations());
+        for (Mutable<ILogicalOperator> opRef : plan.getRoots()) {
+            compileOpRef(opRef, spec, builder, outerPlanSchema);
+            rootOps.add(opRef.getValue());
+        }
+        reviseEdges(builder);
+        operatorVisitedToParents.clear();
+        builder.buildSpec(rootOps);
+        spec.setConnectorPolicyAssignmentPolicy(new ConnectorPolicyAssignmentPolicy());
+        return spec;
+    }
+
+    private void compileOpRef(Mutable<ILogicalOperator> opRef, IOperatorDescriptorRegistry spec, IHyracksJobBuilder builder,
+            IOperatorSchema outerPlanSchema) throws AlgebricksException {
+        ILogicalOperator op = opRef.getValue();
+        int n = op.getInputs().size();
+        IOperatorSchema[] schemas = new IOperatorSchema[n];
+        int i = 0;
+        for (Mutable<ILogicalOperator> opRef2 : op.getInputs()) {
+            List<Mutable<ILogicalOperator>> parents = operatorVisitedToParents.get(opRef2);
+            if (parents == null) {
+                parents = new ArrayList<Mutable<ILogicalOperator>>();
+                operatorVisitedToParents.put(opRef2, parents);
+                parents.add(opRef);
+                compileOpRef(opRef2, spec, builder, outerPlanSchema);
+                schemas[i++] = context.getSchema(opRef2.getValue());
+            } else {
+                if (!parents.contains(opRef))
+                    parents.add(opRef);
+                schemas[i++] = context.getSchema(opRef2.getValue());
+                continue;
+            }
+        }
+
+        IOperatorSchema opSchema = new OperatorSchemaImpl();
+        context.putSchema(op, opSchema);
+        op.getVariablePropagationPolicy().propagateVariables(opSchema, schemas);
+        op.contributeRuntimeOperator(builder, context, opSchema, schemas, outerPlanSchema);
+    }
+
+    private void reviseEdges(IHyracksJobBuilder builder) {
+        /**
+         * revise the edges for the case of replicate operator
+         */
+        for (Entry<Mutable<ILogicalOperator>, List<Mutable<ILogicalOperator>>> entry : operatorVisitedToParents
+                .entrySet()) {
+            Mutable<ILogicalOperator> child = entry.getKey();
+            List<Mutable<ILogicalOperator>> parents = entry.getValue();
+            if (parents.size() > 1) {
+                int i = 0;
+                for (Mutable<ILogicalOperator> parent : parents) {
+                    builder.contributeGraphEdge(child.getValue(), i, parent.getValue(), 0);
+                    i++;
+                }
+            }
+        }
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AbstractRuleController.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AbstractRuleController.java
new file mode 100644
index 0000000..3382c6e
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AbstractRuleController.java
@@ -0,0 +1,130 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import java.util.Collection;
+import java.util.logging.Level;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint.LogicalOperatorPrettyPrintVisitor;
+import edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint.PlanPrettyPrinter;
+import edu.uci.ics.hyracks.algebricks.core.config.AlgebricksConfig;
+
+public abstract class AbstractRuleController {
+
+    protected IOptimizationContext context;
+    private LogicalOperatorPrettyPrintVisitor pvisitor = new LogicalOperatorPrettyPrintVisitor();
+
+    public AbstractRuleController() {
+    }
+
+    public void setContext(IOptimizationContext context) {
+        this.context = context;
+    }
+
+    /**
+     * Each rewriting strategy may differ in the
+     * 
+     * @param root
+     * @param ruleClasses
+     * @return true iff one of the rules in the collection fired
+     */
+    public abstract boolean rewriteWithRuleCollection(Mutable<ILogicalOperator> root,
+            Collection<IAlgebraicRewriteRule> rules) throws AlgebricksException;
+
+    /**
+     * @param opRef
+     * @param rule
+     * @return true if any rewrite was fired, either on opRef or any operator
+     *         under it.
+     */
+    protected boolean rewriteOperatorRef(Mutable<ILogicalOperator> opRef, IAlgebraicRewriteRule rule)
+            throws AlgebricksException {
+        return rewriteOperatorRef(opRef, rule, true, false);
+    }
+
+    private String getPlanString(Mutable<ILogicalOperator> opRef) throws AlgebricksException {
+        if (AlgebricksConfig.ALGEBRICKS_LOGGER.isLoggable(Level.FINE)) {
+            StringBuilder sb = new StringBuilder();
+            PlanPrettyPrinter.printOperator((AbstractLogicalOperator) opRef.getValue(), sb, pvisitor, 0);
+            return sb.toString();
+        }
+        return null;
+    }
+
+    private void printRuleApplication(IAlgebraicRewriteRule rule, String beforePlan, String afterPlan)
+            throws AlgebricksException {
+        if (AlgebricksConfig.ALGEBRICKS_LOGGER.isLoggable(Level.FINE)) {
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine(">>>> Rule " + rule.getClass() + " fired.\n");
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine(">>>> Before plan\n" + beforePlan + "\n");
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine(">>>> After plan\n" + afterPlan + "\n");
+        }
+    }
+
+    protected boolean rewriteOperatorRef(Mutable<ILogicalOperator> opRef, IAlgebraicRewriteRule rule,
+            boolean enterNestedPlans, boolean fullDFS) throws AlgebricksException {
+
+        String preBeforePlan = getPlanString(opRef);
+        if (rule.rewritePre(opRef, context)) {
+            String preAfterPlan = getPlanString(opRef);
+            printRuleApplication(rule, preBeforePlan, preAfterPlan);
+            return true;
+        }
+        boolean rewritten = false;
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+
+        for (Mutable<ILogicalOperator> inp : op.getInputs()) {
+            if (rewriteOperatorRef(inp, rule, enterNestedPlans, fullDFS)) {
+                rewritten = true;
+                if (!fullDFS) {
+                    break;
+                }
+            }
+        }
+
+        if (op.hasNestedPlans() && enterNestedPlans) {
+            AbstractOperatorWithNestedPlans o2 = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan p : o2.getNestedPlans()) {
+                for (Mutable<ILogicalOperator> r : p.getRoots()) {
+                    if (rewriteOperatorRef(r, rule, enterNestedPlans, fullDFS)) {
+                        rewritten = true;
+                        if (!fullDFS) {
+                            break;
+                        }
+                    }
+                }
+                if (rewritten && !fullDFS) {
+                    break;
+                }
+            }
+        }
+
+        String postBeforePlan = getPlanString(opRef);
+        if (rule.rewritePost(opRef, context)) {
+            String postAfterPlan = getPlanString(opRef);
+            printRuleApplication(rule, postBeforePlan, postAfterPlan);
+            return true;
+        }
+
+        return rewritten;
+    }
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java
new file mode 100644
index 0000000..7c63e01
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java
@@ -0,0 +1,285 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.EquivalenceClass;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionEvalSizeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IMergeAggregationExpressionFactory;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableEvalSizeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.FunctionalDependency;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.ILogicalPropertiesVector;
+
+public class AlgebricksOptimizationContext implements IOptimizationContext {
+
+    private int varCounter;
+    private final IExpressionEvalSizeComputer expressionEvalSizeComputer;
+    private final IMergeAggregationExpressionFactory mergeAggregationExpressionFactory;
+    private final PhysicalOptimizationConfig physicalOptimizationConfig;
+    private final IVariableEvalSizeEnvironment varEvalSizeEnv = new IVariableEvalSizeEnvironment() {
+
+        Map<LogicalVariable, Integer> varSizeMap = new HashMap<LogicalVariable, Integer>();
+
+        @Override
+        public void setVariableEvalSize(LogicalVariable var, int size) {
+            varSizeMap.put(var, size);
+        }
+
+        @Override
+        public int getVariableEvalSize(LogicalVariable var) {
+            return varSizeMap.get(var);
+        }
+    };
+
+    private Map<ILogicalOperator, IVariableTypeEnvironment> typeEnvMap = new HashMap<ILogicalOperator, IVariableTypeEnvironment>();
+
+    private Map<ILogicalOperator, HashSet<ILogicalOperator>> alreadyCompared = new HashMap<ILogicalOperator, HashSet<ILogicalOperator>>();
+    private Map<IAlgebraicRewriteRule, HashSet<ILogicalOperator>> dontApply = new HashMap<IAlgebraicRewriteRule, HashSet<ILogicalOperator>>();
+    private Map<LogicalVariable, FunctionalDependency> recordToPrimaryKey = new HashMap<LogicalVariable, FunctionalDependency>();
+
+    @SuppressWarnings("unchecked")
+    private IMetadataProvider metadataProvider;
+    private HashSet<LogicalVariable> notToBeInlinedVars = new HashSet<LogicalVariable>();
+
+    protected final Map<ILogicalOperator, List<FunctionalDependency>> fdGlobalMap = new HashMap<ILogicalOperator, List<FunctionalDependency>>();
+    protected final Map<ILogicalOperator, Map<LogicalVariable, EquivalenceClass>> eqClassGlobalMap = new HashMap<ILogicalOperator, Map<LogicalVariable, EquivalenceClass>>();
+
+    protected final Map<ILogicalOperator, ILogicalPropertiesVector> logicalProps = new HashMap<ILogicalOperator, ILogicalPropertiesVector>();
+    private final int frameSize;
+    private final IExpressionTypeComputer expressionTypeComputer;
+    private final INullableTypeComputer nullableTypeComputer;
+
+    public AlgebricksOptimizationContext(int varCounter, int frameSize,
+            IExpressionEvalSizeComputer expressionEvalSizeComputer,
+            IMergeAggregationExpressionFactory mergeAggregationExpressionFactory,
+            IExpressionTypeComputer expressionTypeComputer, INullableTypeComputer nullableTypeComputer,
+            PhysicalOptimizationConfig physicalOptimizationConfig) {
+        this.varCounter = varCounter;
+        this.frameSize = frameSize;
+        this.expressionEvalSizeComputer = expressionEvalSizeComputer;
+        this.mergeAggregationExpressionFactory = mergeAggregationExpressionFactory;
+        this.expressionTypeComputer = expressionTypeComputer;
+        this.nullableTypeComputer = nullableTypeComputer;
+        this.physicalOptimizationConfig = physicalOptimizationConfig;
+    }
+
+    public int getVarCounter() {
+        return varCounter;
+    }
+
+    public void setVarCounter(int varCounter) {
+        this.varCounter = varCounter;
+    }
+
+    public LogicalVariable newVar() {
+        varCounter++;
+        LogicalVariable var = new LogicalVariable(varCounter);
+        return var;
+    }
+
+    @SuppressWarnings("unchecked")
+    public IMetadataProvider getMetadataProvider() {
+        return metadataProvider;
+    }
+
+    public void setMetadataDeclarations(IMetadataProvider<?, ?> metadataProvider) {
+        this.metadataProvider = metadataProvider;
+    }
+
+    public boolean checkIfInDontApplySet(IAlgebraicRewriteRule rule, ILogicalOperator op) {
+        HashSet<ILogicalOperator> operators = dontApply.get(rule);
+        if (operators == null) {
+            return false;
+        } else {
+            return operators.contains(op);
+        }
+    }
+
+    public void addToDontApplySet(IAlgebraicRewriteRule rule, ILogicalOperator op) {
+        HashSet<ILogicalOperator> operators = dontApply.get(rule);
+        if (operators == null) {
+            HashSet<ILogicalOperator> os = new HashSet<ILogicalOperator>();
+            os.add(op);
+            dontApply.put(rule, os);
+        } else {
+            operators.add(op);
+        }
+
+    }
+
+    /*
+     * returns true if op1 and op2 have already been compared
+     */
+    public boolean checkAndAddToAlreadyCompared(ILogicalOperator op1, ILogicalOperator op2) {
+        HashSet<ILogicalOperator> ops = alreadyCompared.get(op1);
+        if (ops == null) {
+            HashSet<ILogicalOperator> newEntry = new HashSet<ILogicalOperator>();
+            newEntry.add(op2);
+            alreadyCompared.put(op1, newEntry);
+            return false;
+        } else {
+            if (ops.contains(op2)) {
+                return true;
+            } else {
+                ops.add(op2);
+                return false;
+            }
+        }
+    }
+
+    public void addNotToBeInlinedVar(LogicalVariable var) {
+        notToBeInlinedVars.add(var);
+    }
+
+    public boolean shouldNotBeInlined(LogicalVariable var) {
+        return notToBeInlinedVars.contains(var);
+    }
+
+    public void addPrimaryKey(FunctionalDependency pk) {
+        assert (pk.getTail().size() == 1);
+        LogicalVariable recordVar = pk.getTail().get(0);
+        recordToPrimaryKey.put(recordVar, pk);
+    }
+
+    public List<LogicalVariable> findPrimaryKey(LogicalVariable recordVar) {
+        FunctionalDependency fd = recordToPrimaryKey.get(recordVar);
+        if (fd == null) {
+            return null;
+        }
+        return fd.getHead();
+    }
+
+    @Override
+    public Map<LogicalVariable, EquivalenceClass> getEquivalenceClassMap(ILogicalOperator op) {
+        return eqClassGlobalMap.get(op);
+    }
+
+    @Override
+    public List<FunctionalDependency> getFDList(ILogicalOperator op) {
+        return fdGlobalMap.get(op);
+    }
+
+    @Override
+    public void putEquivalenceClassMap(ILogicalOperator op, Map<LogicalVariable, EquivalenceClass> eqClassMap) {
+        this.eqClassGlobalMap.put(op, eqClassMap);
+    }
+
+    @Override
+    public void putFDList(ILogicalOperator op, List<FunctionalDependency> fdList) {
+        this.fdGlobalMap.put(op, fdList);
+    }
+
+    @Override
+    public ILogicalPropertiesVector getLogicalPropertiesVector(ILogicalOperator op) {
+        return logicalProps.get(op);
+    }
+
+    @Override
+    public void putLogicalPropertiesVector(ILogicalOperator op, ILogicalPropertiesVector v) {
+        logicalProps.put(op, v);
+    }
+
+    @Override
+    public IExpressionEvalSizeComputer getExpressionEvalSizeComputer() {
+        return expressionEvalSizeComputer;
+    }
+
+    @Override
+    public IVariableEvalSizeEnvironment getVariableEvalSizeEnvironment() {
+        return varEvalSizeEnv;
+    }
+
+    @Override
+    public int getFrameSize() {
+        return frameSize;
+    }
+
+    public IMergeAggregationExpressionFactory getMergeAggregationExpressionFactory() {
+        return mergeAggregationExpressionFactory;
+    }
+
+    public PhysicalOptimizationConfig getPhysicalOptimizationConfig() {
+        return physicalOptimizationConfig;
+    }
+
+    @Override
+    public IVariableTypeEnvironment getOutputTypeEnvironment(ILogicalOperator op) {
+        return typeEnvMap.get(op);
+    }
+
+    @Override
+    public void setOutputTypeEnvironment(ILogicalOperator op, IVariableTypeEnvironment env) {
+        typeEnvMap.put(op, env);
+    }
+
+    @Override
+    public IExpressionTypeComputer getExpressionTypeComputer() {
+        return expressionTypeComputer;
+    }
+
+    @Override
+    public INullableTypeComputer getNullableTypeComputer() {
+        return nullableTypeComputer;
+    }
+
+    @Override
+    public void invalidateTypeEnvironmentForOperator(ILogicalOperator op) {
+        typeEnvMap.put(op, null);
+    }
+
+    @Override
+    public void computeAndSetTypeEnvironmentForOperator(ILogicalOperator op) throws AlgebricksException {
+        setOutputTypeEnvironment(op, op.computeOutputTypeEnvironment(this));
+    }
+
+    @Override
+    public void updatePrimaryKeys(Map<LogicalVariable, LogicalVariable> mappedVars) {
+        for (Map.Entry<LogicalVariable, FunctionalDependency> me : recordToPrimaryKey.entrySet()) {
+            FunctionalDependency fd = me.getValue();
+            List<LogicalVariable> hd = new ArrayList<LogicalVariable>();
+            for (LogicalVariable v : fd.getHead()) {
+                LogicalVariable v2 = mappedVars.get(v);
+                if (v2 == null) {
+                    hd.add(v);
+                } else {
+                    hd.add(v2);
+                }
+            }
+            List<LogicalVariable> tl = new ArrayList<LogicalVariable>();
+            for (LogicalVariable v : fd.getTail()) {
+                LogicalVariable v2 = mappedVars.get(v);
+                if (v2 == null) {
+                    tl.add(v);
+                } else {
+                    tl.add(v2);
+                }
+            }
+            me.setValue(new FunctionalDependency(hd, tl));
+        }
+    }
+}
\ No newline at end of file
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/HeuristicOptimizer.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/HeuristicOptimizer.java
new file mode 100644
index 0000000..471b71c
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/HeuristicOptimizer.java
@@ -0,0 +1,113 @@
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.common.utils.Pair;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.PhysicalOperatorTag;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint.LogicalOperatorPrettyPrintVisitor;
+import edu.uci.ics.hyracks.algebricks.core.algebra.prettyprint.PlanPrettyPrinter;
+import edu.uci.ics.hyracks.algebricks.core.config.AlgebricksConfig;
+
+public class HeuristicOptimizer {
+
+    public static PhysicalOperatorTag[] hyraxOperators = new PhysicalOperatorTag[] {
+            PhysicalOperatorTag.DATASOURCE_SCAN, PhysicalOperatorTag.BTREE_SEARCH,
+            PhysicalOperatorTag.EXTERNAL_GROUP_BY, PhysicalOperatorTag.HASH_GROUP_BY, PhysicalOperatorTag.HDFS_READER,
+            PhysicalOperatorTag.HYBRID_HASH_JOIN, PhysicalOperatorTag.IN_MEMORY_HASH_JOIN,
+            PhysicalOperatorTag.NESTED_LOOP, PhysicalOperatorTag.PRE_SORTED_DISTINCT_BY,
+            PhysicalOperatorTag.PRE_CLUSTERED_GROUP_BY, PhysicalOperatorTag.SPLIT, PhysicalOperatorTag.STABLE_SORT,
+            PhysicalOperatorTag.UNION_ALL };
+    public static PhysicalOperatorTag[] hyraxOperatorsBelowWhichJobGenIsDisabled = new PhysicalOperatorTag[] {};
+
+    public static boolean isHyraxOp(PhysicalOperatorTag opTag) {
+        for (PhysicalOperatorTag t : hyraxOperators) {
+            if (t == opTag) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private IOptimizationContext context;
+    private List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> logicalRewrites;
+    private List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> physicalRewrites;
+    private ILogicalPlan plan;
+    private LogicalOperatorPrettyPrintVisitor ppvisitor = new LogicalOperatorPrettyPrintVisitor();
+
+    public HeuristicOptimizer(ILogicalPlan plan,
+            List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> logicalRewrites,
+            List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> physicalRewrites,
+            IOptimizationContext context) {
+        this.plan = plan;
+        this.context = context;
+        this.logicalRewrites = logicalRewrites;
+        this.physicalRewrites = physicalRewrites;
+    }
+
+    public void optimize() throws AlgebricksException {
+        if (plan == null) {
+            return;
+        }
+        if (AlgebricksConfig.DEBUG) {
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine("Starting logical optimizations.\n");
+        }
+
+        StringBuilder sb = new StringBuilder();
+        PlanPrettyPrinter.printPlan(plan, sb, ppvisitor, 0);
+        AlgebricksConfig.ALGEBRICKS_LOGGER.fine("Logical Plan:\n" + sb.toString());
+        runOptimizationSets(plan, logicalRewrites);
+        computeSchemaBottomUpForPlan(plan);
+        runPhysicalOptimizations(plan, physicalRewrites);
+        StringBuilder sb2 = new StringBuilder();
+        PlanPrettyPrinter.printPlan(plan, sb2, ppvisitor, 0);
+        AlgebricksConfig.ALGEBRICKS_LOGGER.info("Optimized Plan:\n" + sb2.toString());
+    }
+
+    private void runOptimizationSets(ILogicalPlan plan,
+            List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> optimSet) throws AlgebricksException {
+        for (Pair<AbstractRuleController, List<IAlgebraicRewriteRule>> ruleList : optimSet) {
+            for (Mutable<ILogicalOperator> r : plan.getRoots()) {
+                ruleList.first.setContext(context);
+                ruleList.first.rewriteWithRuleCollection(r, ruleList.second);
+            }
+        }
+    }
+
+    private static void computeSchemaBottomUpForPlan(ILogicalPlan p) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> r : p.getRoots()) {
+            computeSchemaBottomUpForOp((AbstractLogicalOperator) r.getValue());
+        }
+    }
+
+    private static void computeSchemaBottomUpForOp(AbstractLogicalOperator op) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> i : op.getInputs()) {
+            computeSchemaBottomUpForOp((AbstractLogicalOperator) i.getValue());
+        }
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans a = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan p : a.getNestedPlans()) {
+                computeSchemaBottomUpForPlan(p);
+            }
+        }
+        op.recomputeSchema();
+    }
+
+    private void runPhysicalOptimizations(ILogicalPlan plan,
+            List<Pair<AbstractRuleController, List<IAlgebraicRewriteRule>>> physicalRewrites)
+            throws AlgebricksException {
+        if (AlgebricksConfig.DEBUG) {
+            AlgebricksConfig.ALGEBRICKS_LOGGER.fine("Starting physical optimizations.\n");
+        }
+        // PhysicalOptimizationsUtil.computeFDsAndEquivalenceClasses(plan);
+        runOptimizationSets(plan, physicalRewrites);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IAlgebraicRewriteRule.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IAlgebraicRewriteRule.java
new file mode 100644
index 0000000..fc39d0b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IAlgebraicRewriteRule.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import org.apache.commons.lang3.mutable.Mutable;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+
+public interface IAlgebraicRewriteRule {
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException;
+
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException;
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IOptimizationContextFactory.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IOptimizationContextFactory.java
new file mode 100644
index 0000000..1373fa7
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/IOptimizationContextFactory.java
@@ -0,0 +1,29 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import edu.uci.ics.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionEvalSizeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IExpressionTypeComputer;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IMergeAggregationExpressionFactory;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.INullableTypeComputer;
+
+public interface IOptimizationContextFactory {
+    public IOptimizationContext createOptimizationContext(int varCounter, int frameSize,
+            IExpressionEvalSizeComputer expressionEvalSizeComputer,
+            IMergeAggregationExpressionFactory mergeAggregationExpressionFactory,
+            IExpressionTypeComputer expressionTypeComputer, INullableTypeComputer nullableTypeComputer,
+            PhysicalOptimizationConfig physicalOptimizationConfig);
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
new file mode 100644
index 0000000..9ce910b
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
@@ -0,0 +1,91 @@
+package edu.uci.ics.hyracks.algebricks.core.rewriter.base;
+
+import java.util.Properties;
+
+public class PhysicalOptimizationConfig {
+    private static final int MB = 1048576;
+    private static final String FRAMESIZE = "FRAMESIZE";
+    private static final String MAX_FRAMES_EXTERNAL_SORT = "MAX_FRAMES_EXTERNAL_SORT";
+    private static final String MAX_FRAMES_EXTERNAL_GROUP_BY = "MAX_FRAMES_EXTERNAL_GROUP_BY";
+
+    private static final String DEFAULT_HASH_GROUP_TABLE_SIZE = "DEFAULT_HASH_GROUP_TABLE_SIZE";
+    private static final String DEFAULT_EXTERNAL_GROUP_TABLE_SIZE = "DEFAULT_EXTERNAL_GROUP_TABLE_SIZE";
+    private static final String DEFAULT_IN_MEM_HASH_JOIN_TABLE_SIZE = "DEFAULT_IN_MEM_HASH_JOIN_TABLE_SIZE";
+
+    private Properties properties = new Properties();
+
+    public PhysicalOptimizationConfig() {
+        int frameSize = 32768;
+        setInt(FRAMESIZE, frameSize);
+        setInt(MAX_FRAMES_EXTERNAL_SORT, (int) (((long) 512 * MB) / frameSize));
+        setInt(MAX_FRAMES_EXTERNAL_GROUP_BY, (int) (((long) 256 * MB) / frameSize));
+
+        // use http://www.rsok.com/~jrm/printprimes.html to find prime numbers
+        setInt(DEFAULT_HASH_GROUP_TABLE_SIZE, 10485767);
+        setInt(DEFAULT_EXTERNAL_GROUP_TABLE_SIZE, 10485767);
+        setInt(DEFAULT_IN_MEM_HASH_JOIN_TABLE_SIZE, 10485767);
+    }
+
+    public int getFrameSize() {
+        return getInt(FRAMESIZE, 32768);
+    }
+
+    public void setFrameSize(int frameSize) {
+        setInt(FRAMESIZE, frameSize);
+    }
+
+    public int getMaxFramesExternalSort() {
+        int frameSize = getFrameSize();
+        return getInt(MAX_FRAMES_EXTERNAL_SORT, (int) (((long) 512 * MB) / frameSize));
+    }
+
+    public void setMaxFramesExternalSort(int frameLimit) {
+        setInt(MAX_FRAMES_EXTERNAL_SORT, frameLimit);
+    }
+
+    public int getMaxFramesExternalGroupBy() {
+        int frameSize = getFrameSize();
+        return getInt(MAX_FRAMES_EXTERNAL_GROUP_BY, (int) (((long) 256 * MB) / frameSize));
+    }
+
+    public void setMaxFramesExternalGroupBy(int frameLimit) {
+        setInt(MAX_FRAMES_EXTERNAL_GROUP_BY, frameLimit);
+    }
+
+    public int getHashGroupByTableSize() {
+        return getInt(DEFAULT_HASH_GROUP_TABLE_SIZE, 10485767);
+    }
+
+    public void setHashGroupByTableSize(int tableSize) {
+        setInt(DEFAULT_HASH_GROUP_TABLE_SIZE, tableSize);
+    }
+
+    public int getExternalGroupByTableSize() {
+        return getInt(DEFAULT_EXTERNAL_GROUP_TABLE_SIZE, 10485767);
+    }
+
+    public void setExternalGroupByTableSize(int tableSize) {
+        setInt(DEFAULT_EXTERNAL_GROUP_TABLE_SIZE, tableSize);
+    }
+
+    public int getInMemHashJoinTableSize() {
+        return getInt(DEFAULT_IN_MEM_HASH_JOIN_TABLE_SIZE, 10485767);
+    }
+
+    public void setInMemHashJoinTableSize(int tableSize) {
+        setInt(DEFAULT_IN_MEM_HASH_JOIN_TABLE_SIZE, tableSize);
+    }
+
+    private void setInt(String property, int value) {
+        properties.setProperty(property, Integer.toString(value));
+    }
+
+    private int getInt(String property, int defaultValue) {
+        String value = properties.getProperty(property);
+        if (value == null)
+            return defaultValue;
+        else
+            return Integer.parseInt(value);
+    }
+
+}
diff --git a/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/utils/Substitution.java b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/utils/Substitution.java
new file mode 100644
index 0000000..c52cdff
--- /dev/null
+++ b/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/utils/Substitution.java
@@ -0,0 +1,25 @@
+/*
+ * Copyright 2009-2010 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package edu.uci.ics.hyracks.algebricks.core.utils;
+
+public class Substitution<T> {
+    public T substituted;
+    public T substitutedWith;
+
+    public Substitution(T substituted, T substitutedWith) {
+        this.substituted = substituted;
+        this.substitutedWith = substitutedWith;
+    }
+}