diff --git a/fullstack/algebricks/algebricks-common/pom.xml b/fullstack/algebricks/algebricks-common/pom.xml
index a5677a5..521ef12 100644
--- a/fullstack/algebricks/algebricks-common/pom.xml
+++ b/fullstack/algebricks/algebricks-common/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-compiler/pom.xml b/fullstack/algebricks/algebricks-compiler/pom.xml
index 8dc083d..bd35835 100644
--- a/fullstack/algebricks/algebricks-compiler/pom.xml
+++ b/fullstack/algebricks/algebricks-compiler/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/AbstractCompilerFactoryBuilder.java b/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/AbstractCompilerFactoryBuilder.java
index f1e7acb..dde4443 100644
--- a/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/AbstractCompilerFactoryBuilder.java
+++ b/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/AbstractCompilerFactoryBuilder.java
@@ -30,6 +30,7 @@
 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.IBinaryHashFunctionFamilyProvider;
 import edu.uci.ics.hyracks.algebricks.data.IBinaryIntegerInspectorFactory;
 import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
 import edu.uci.ics.hyracks.algebricks.data.IPrinterFactoryProvider;
@@ -44,6 +45,7 @@
     protected ITypeTraitProvider typeTraitProvider;
     protected ISerializerDeserializerProvider serializerDeserializerProvider;
     protected IBinaryHashFunctionFactoryProvider hashFunctionFactoryProvider;
+    protected IBinaryHashFunctionFamilyProvider hashFunctionFamilyProvider;
     protected IBinaryComparatorFactoryProvider comparatorFactoryProvider;
     protected IBinaryBooleanInspectorFactory binaryBooleanInspectorFactory;
     protected IBinaryIntegerInspectorFactory binaryIntegerInspectorFactory;
@@ -94,6 +96,14 @@
         return hashFunctionFactoryProvider;
     }
 
+    public void setHashFunctionFamilyProvider(IBinaryHashFunctionFamilyProvider hashFunctionFamilyProvider) {
+        this.hashFunctionFamilyProvider = hashFunctionFamilyProvider;
+    }
+
+    public IBinaryHashFunctionFamilyProvider getHashFunctionFamilyProvider() {
+        return hashFunctionFamilyProvider;
+    }
+
     public void setComparatorFactoryProvider(IBinaryComparatorFactoryProvider comparatorFactoryProvider) {
         this.comparatorFactoryProvider = comparatorFactoryProvider;
     }
diff --git a/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java b/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
index 1d21463..edc1b66 100644
--- a/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
+++ b/fullstack/algebricks/algebricks-compiler/src/main/java/edu/uci/ics/hyracks/algebricks/compiler/api/HeuristicCompilerFactoryBuilder.java
@@ -84,11 +84,12 @@
                     public JobSpecification createJob(Object appContext) throws AlgebricksException {
                         AlgebricksConfig.ALGEBRICKS_LOGGER.fine("Starting Job Generation.\n");
                         JobGenContext context = new JobGenContext(null, metadata, appContext,
-                                serializerDeserializerProvider, hashFunctionFactoryProvider, comparatorFactoryProvider,
-                                typeTraitProvider, binaryBooleanInspectorFactory, binaryIntegerInspectorFactory,
-                                printerProvider, nullWriterFactory, normalizedKeyComputerFactoryProvider,
-                                expressionRuntimeProvider, expressionTypeComputer, nullableTypeComputer, oc,
-                                expressionEvalSizeComputer, partialAggregationTypeComputer, frameSize, clusterLocations);
+                                serializerDeserializerProvider, hashFunctionFactoryProvider,
+                                hashFunctionFamilyProvider, comparatorFactoryProvider, typeTraitProvider,
+                                binaryBooleanInspectorFactory, binaryIntegerInspectorFactory, printerProvider,
+                                nullWriterFactory, normalizedKeyComputerFactoryProvider, expressionRuntimeProvider,
+                                expressionTypeComputer, nullableTypeComputer, oc, expressionEvalSizeComputer,
+                                partialAggregationTypeComputer, frameSize, clusterLocations);
                         PlanCompiler pc = new PlanCompiler(context);
                         return pc.compilePlan(plan, null);
                     }
diff --git a/fullstack/algebricks/algebricks-core/pom.xml b/fullstack/algebricks/algebricks-core/pom.xml
index a74a540..def5b35 100644
--- a/fullstack/algebricks/algebricks-core/pom.xml
+++ b/fullstack/algebricks/algebricks-core/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java
index 165fccd..6701385 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/ILogicalOperator.java
@@ -89,4 +89,9 @@
     public IPhysicalPropertiesVector getDeliveredPhysicalProperties();
 
     public void computeDeliveredPhysicalProperties(IOptimizationContext context) throws AlgebricksException;
+    
+    /**
+     * Indicates whether the expressions used by this operator must be variable reference expressions.
+     */
+    public boolean requiresVariableReferenceExpressions();
 }
\ No newline at end of file
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java
index 468d25c..0aa1ff6 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/IOptimizationContext.java
@@ -51,6 +51,8 @@
      * returns true if op1 and op2 have already been compared
      */
     public abstract boolean checkAndAddToAlreadyCompared(ILogicalOperator op1, ILogicalOperator op2);
+    
+    public abstract void removeFromAlreadyCompared(ILogicalOperator op1);
 
     public abstract void addNotToBeInlinedVar(LogicalVariable var);
 
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java
index 5234d2c..b8bdf3e 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/LogicalOperatorTag.java
@@ -20,6 +20,7 @@
     CLUSTER,
     DATASOURCESCAN,
     DISTINCT,
+    DISTRIBUTE_RESULT,
     GROUP,
     EMPTYTUPLESOURCE,
     EXCHANGE,
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java
index a969372..32cfb9a 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/base/PhysicalOperatorTag.java
@@ -7,6 +7,7 @@
     BTREE_SEARCH,
     STATS,
     DATASOURCE_SCAN,
+    DISTRIBUTE_RESULT,
     EMPTY_TUPLE_SOURCE,
     EXTERNAL_GROUP_BY,
     IN_MEMORY_HASH_JOIN,
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java
index bf3f82b..b284b22 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/ScalarFunctionCallExpression.java
@@ -39,9 +39,11 @@
 
     @Override
     public ScalarFunctionCallExpression cloneExpression() {
-        cloneAnnotations();
         List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
-        return new ScalarFunctionCallExpression(finfo, clonedArgs);
+        ScalarFunctionCallExpression funcExpr = new ScalarFunctionCallExpression(finfo, clonedArgs);
+        funcExpr.getAnnotations().putAll(cloneAnnotations());
+        funcExpr.setOpaqueParameters(this.getOpaqueParameters());
+        return funcExpr;
     }
 
     @Override
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java
index 71932d8..652f9b0 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/expressions/UnnestingFunctionCallExpression.java
@@ -45,6 +45,7 @@
         List<Mutable<ILogicalExpression>> clonedArgs = cloneArguments();
         UnnestingFunctionCallExpression ufce = new UnnestingFunctionCallExpression(finfo, clonedArgs);
         ufce.setReturnsUniqueValues(returnsUniqueValues);
+        ufce.setOpaqueParameters(this.getOpaqueParameters());
         return ufce;
     }
 
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java
index 899b633..82187e3 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/metadata/IMetadataProvider.java
@@ -51,6 +51,10 @@
             int[] printColumns, IPrinterFactory[] printerFactories, RecordDescriptor inputDesc)
             throws AlgebricksException;
 
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getResultHandleRuntime(IDataSink sink,
+            int[] printColumns, IPrinterFactory[] printerFactories, RecordDescriptor inputDesc, boolean ordered,
+            JobSpecification spec) throws AlgebricksException;
+
     public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getWriteResultRuntime(IDataSource<S> dataSource,
             IOperatorSchema propagatedSchema, List<LogicalVariable> keys, LogicalVariable payLoadVar,
             JobGenContext context, JobSpecification jobSpec) throws AlgebricksException;
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java
index dc0edfe..64dbdef 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AbstractLogicalOperator.java
@@ -182,4 +182,9 @@
         return new PropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getNullableTypeComputer(),
                 ctx.getMetadataProvider(), TypePropagationPolicy.ALL, envPointers);
     }
+    
+    @Override
+    public boolean requiresVariableReferenceExpressions() {
+        return true;
+    }
 }
\ No newline at end of file
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java
index a4dc2e0..4543997 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/AssignOperator.java
@@ -89,4 +89,8 @@
         return env;
     }
 
+    @Override
+    public boolean requiresVariableReferenceExpressions() {
+        return false;
+    }
 }
\ No newline at end of file
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java
index 3227f3d..3c21c8f 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DataSourceScanOperator.java
@@ -106,5 +106,4 @@
         }
         return env;
     }
-
 }
\ No newline at end of file
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java
index 20aa574..03bfcba 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DieOperator.java
@@ -81,4 +81,8 @@
         return createPropagatingAllInputsTypeEnvironment(ctx);
     }
 
+    @Override
+    public boolean requiresVariableReferenceExpressions() {
+        return false;
+    }
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java
index ee0dcf6..b1da831 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistinctOperator.java
@@ -28,6 +28,7 @@
 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.typing.NonPropagatingTypeEnvironment;
 import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
 import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
 
@@ -49,12 +50,34 @@
 
     @Override
     public void recomputeSchema() {
-        schema = new ArrayList<LogicalVariable>(inputs.get(0).getValue().getSchema());
+        if (schema == null) {
+            schema = new ArrayList<LogicalVariable>();
+        }
+        schema.clear();
+        for (Mutable<ILogicalExpression> eRef : expressions) {
+            ILogicalExpression e = eRef.getValue();
+            if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression v = (VariableReferenceExpression) e;
+                schema.add(v.getVariableReference());
+            }
+        }
     }
 
     @Override
     public VariablePropagationPolicy getVariablePropagationPolicy() {
-        return VariablePropagationPolicy.ALL;
+        return new VariablePropagationPolicy() {
+            @Override
+            public void propagateVariables(IOperatorSchema target, IOperatorSchema... sources)
+                    throws AlgebricksException {
+                for (Mutable<ILogicalExpression> eRef : expressions) {
+                    ILogicalExpression e = eRef.getValue();
+                    if (e.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                        VariableReferenceExpression v = (VariableReferenceExpression) e;
+                        target.addVariable(v.getVariableReference());
+                    }
+                }
+            }
+        };
     }
 
     @Override
@@ -105,7 +128,16 @@
 
     @Override
     public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
-        return createPropagatingAllInputsTypeEnvironment(ctx);
+        IVariableTypeEnvironment env = new NonPropagatingTypeEnvironment(ctx.getExpressionTypeComputer(), ctx.getMetadataProvider());
+        IVariableTypeEnvironment childEnv = ctx.getOutputTypeEnvironment(inputs.get(0).getValue());
+        for (Mutable<ILogicalExpression> exprRef : expressions) {
+            ILogicalExpression expr = exprRef.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression varRefExpr = (VariableReferenceExpression) expr;
+                env.setVarType(varRefExpr.getVariableReference(), childEnv.getType(expr));
+            }
+        }
+        return env;
     }
 
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistributeResultOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistributeResultOperator.java
new file mode 100644
index 0000000..6ca6d87
--- /dev/null
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/DistributeResultOperator.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 DistributeResultOperator extends AbstractLogicalOperator {
+    private List<Mutable<ILogicalExpression>> expressions;
+    private IDataSink dataSink;
+
+    public DistributeResultOperator(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.DISTRIBUTE_RESULT;
+    }
+
+    @Override
+    public <R, T> R accept(ILogicalOperatorVisitor<R, T> visitor, T arg) throws AlgebricksException {
+        return visitor.visitDistributeResultOperator(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/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java
index 101b6f5..5aa858f 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/ExtensionOperator.java
@@ -51,7 +51,7 @@
 
     @Override
     public boolean acceptExpressionTransform(ILogicalExpressionReferenceTransform transform) throws AlgebricksException {
-        return false;
+        return delegate.acceptExpressionTransform(transform);
     }
 
     @Override
@@ -108,4 +108,13 @@
         return this.createPropagatingAllInputsTypeEnvironment(ctx);
     }
 
+    @Override
+    public String toString() {
+        return delegate.toString();
+    }
+    
+    public IOperatorExtension getDelegate() {
+        return delegate;
+    }
+
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java
index 98c3301..0a80337 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/IOperatorExtension.java
@@ -14,6 +14,7 @@
  */
 package edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical;
 
+import java.util.Collection;
 import java.util.List;
 
 import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
@@ -42,5 +43,8 @@
     void setPhysicalOperator(IPhysicalOperator physicalOperator);
 
     ExecutionMode getExecutionMode();
-
+    
+    public void getUsedVariables(Collection<LogicalVariable> usedVars);
+    
+    public void getProducedVariables(Collection<LogicalVariable> producedVars);
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java
index 3c6a699..8e67ed9 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/LimitOperator.java
@@ -109,5 +109,4 @@
     public IVariableTypeEnvironment computeOutputTypeEnvironment(ITypingContext ctx) throws AlgebricksException {
         return createPropagatingAllInputsTypeEnvironment(ctx);
     }
-
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java
index 8c611b0..fda920a 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/SelectOperator.java
@@ -102,4 +102,8 @@
         return env;
     }
 
+    @Override
+    public boolean requiresVariableReferenceExpressions() {
+        return false;
+    }
 }
\ No newline at end of file
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java
index 0539cbe..1b4be1e 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/FDsAndEquivClassesVisitor.java
@@ -47,8 +47,10 @@
 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.DistributeResultOperator;
 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;
@@ -64,7 +66,6 @@
 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;
@@ -476,6 +477,14 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator 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);
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
index 31061db..ac6d887 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
@@ -38,6 +38,7 @@
 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.DistributeResultOperator;
 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;
@@ -345,7 +346,7 @@
         AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
         if (aop.getOperatorTag() != LogicalOperatorTag.UNNEST_MAP)
             return Boolean.FALSE;
-        UnnestOperator unnestOpArg = (UnnestOperator) copyAndSubstituteVar(op, arg);
+        UnnestMapOperator unnestOpArg = (UnnestMapOperator) copyAndSubstituteVar(op, arg);
         boolean isomorphic = VariableUtilities.varListEqualUnordered(op.getVariables(), unnestOpArg.getVariables());
         if (!isomorphic)
             return Boolean.FALSE;
@@ -425,6 +426,17 @@
     }
 
     @Override
+    public Boolean visitDistributeResultOperator(DistributeResultOperator op, ILogicalOperator arg)
+            throws AlgebricksException {
+        AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
+        if (aop.getOperatorTag() != LogicalOperatorTag.DISTRIBUTE_RESULT)
+            return Boolean.FALSE;
+        DistributeResultOperator writeOpArg = (DistributeResultOperator) 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)
@@ -762,6 +774,14 @@
         }
 
         @Override
+        public ILogicalOperator visitDistributeResultOperator(DistributeResultOperator op, Void arg)
+                throws AlgebricksException {
+            ArrayList<Mutable<ILogicalExpression>> newExpressions = new ArrayList<Mutable<ILogicalExpression>>();
+            deepCopyExpressionRefs(newExpressions, op.getExpressions());
+            return new DistributeResultOperator(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());
@@ -784,8 +804,8 @@
             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());
+            Mutable<ILogicalExpression> newFilterExpression = new MutableObject<ILogicalExpression>(
+                    ((AbstractLogicalExpression) op.getFilterExpression()).cloneExpression());
             return new IndexInsertDeleteOperator(op.getDataSourceIndex(), newPrimaryKeyExpressions,
                     newSecondaryKeyExpressions, newFilterExpression, op.getOperation());
         }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
index 562bb4c..b9544c7 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
@@ -37,8 +37,10 @@
 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.DistributeResultOperator;
 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;
@@ -54,7 +56,6 @@
 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;
@@ -230,6 +231,13 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator 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;
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java
index 9b2f5a0..8f1d686 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/LogicalPropertiesVisitor.java
@@ -29,8 +29,10 @@
 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.DistributeResultOperator;
 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;
@@ -46,7 +48,6 @@
 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;
@@ -240,6 +241,12 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator op, IOptimizationContext arg)
+            throws AlgebricksException {
+        return null;
+    }
+
+    @Override
     public Void visitWriteResultOperator(WriteResultOperator op, IOptimizationContext arg) throws AlgebricksException {
         // TODO Auto-generated method stub
         return null;
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java
index 994c6cb..31adcba 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/ProducedVariableVisitor.java
@@ -32,8 +32,10 @@
 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.DistributeResultOperator;
 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;
@@ -49,7 +51,6 @@
 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;
@@ -223,6 +224,11 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator op, Void arg) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
     public Void visitWriteResultOperator(WriteResultOperator op, Void arg) throws AlgebricksException {
         return null;
     }
@@ -249,6 +255,7 @@
 
     @Override
     public Void visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+        op.getDelegate().getProducedVariables(producedVariables);
         return null;
     }
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java
index 9295179..cd0cee3 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SchemaVariableVisitor.java
@@ -31,8 +31,10 @@
 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.DistributeResultOperator;
 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;
@@ -48,7 +50,6 @@
 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;
@@ -85,7 +86,13 @@
 
     @Override
     public Void visitDistinctOperator(DistinctOperator op, Void arg) throws AlgebricksException {
-        standardLayout(op);
+        for (Mutable<ILogicalExpression> exprRef : op.getExpressions()) {
+            ILogicalExpression expr = exprRef.getValue();
+            if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                VariableReferenceExpression varRefExpr = (VariableReferenceExpression) expr;
+                schemaVariables.add(varRefExpr.getVariableReference());
+            }
+        }
         return null;
     }
 
@@ -232,6 +239,12 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator op, Void arg) throws AlgebricksException {
+        standardLayout(op);
+        return null;
+    }
+
+    @Override
     public Void visitWriteResultOperator(WriteResultOperator op, Void arg) throws AlgebricksException {
         standardLayout(op);
         return null;
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java
index 11e56ca..69fb3f8 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/SubstituteVariableVisitor.java
@@ -33,8 +33,10 @@
 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.DistributeResultOperator;
 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;
@@ -51,7 +53,6 @@
 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;
@@ -335,6 +336,16 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator 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);
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java
index 3a82ccd..5361a19 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/UsedVariableVisitor.java
@@ -25,14 +25,17 @@
 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.IPhysicalOperator;
 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.DistributeResultOperator;
 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;
@@ -49,13 +52,17 @@
 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.operators.physical.HashPartitionExchangePOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.HashPartitionMergeExchangePOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.RangePartitionPOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.SortMergeExchangePOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.properties.OrderColumn;
 import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalOperatorVisitor;
 
 public class UsedVariableVisitor implements ILogicalOperatorVisitor<Void, Void> {
@@ -106,8 +113,49 @@
     }
 
     @Override
-    public Void visitExchangeOperator(ExchangeOperator op, Void arg) {
-        // does not use any variable
+    public Void visitExchangeOperator(ExchangeOperator op, Void arg) throws AlgebricksException {
+        // Used variables depend on the physical operator.
+        if (op.getPhysicalOperator() != null) {
+            IPhysicalOperator physOp = op.getPhysicalOperator();
+            switch (physOp.getOperatorTag()) {
+                case BROADCAST_EXCHANGE:
+                case ONE_TO_ONE_EXCHANGE:
+                case RANDOM_MERGE_EXCHANGE: {
+                    // No variables used.
+                    break;
+                }
+                case HASH_PARTITION_EXCHANGE: {
+                    HashPartitionExchangePOperator concreteOp = (HashPartitionExchangePOperator) physOp;
+                    usedVariables.addAll(concreteOp.getHashFields());
+                    break;
+                }
+                case HASH_PARTITION_MERGE_EXCHANGE: {
+                    HashPartitionMergeExchangePOperator concreteOp = (HashPartitionMergeExchangePOperator) physOp;
+                    usedVariables.addAll(concreteOp.getPartitionFields());
+                    for (OrderColumn orderCol : concreteOp.getOrderColumns()) {
+                        usedVariables.add(orderCol.getColumn());
+                    }
+                    break;
+                }
+                case SORT_MERGE_EXCHANGE: {
+                    SortMergeExchangePOperator concreteOp = (SortMergeExchangePOperator) physOp;
+                    for (OrderColumn orderCol : concreteOp.getSortColumns()) {
+                        usedVariables.add(orderCol.getColumn());
+                    }
+                    break;
+                }
+                case RANGE_PARTITION_EXCHANGE: {
+                    RangePartitionPOperator concreteOp = (RangePartitionPOperator) physOp;
+                    for (OrderColumn partCol : concreteOp.getPartitioningFields()) {
+                        usedVariables.add(partCol.getColumn());
+                    }
+                    break;
+                }
+                default: {
+                    throw new AlgebricksException("Unhandled physical operator tag '" + physOp.getOperatorTag() + "'.");
+                }
+            }
+        }
         return null;
     }
 
@@ -257,6 +305,14 @@
     }
 
     @Override
+    public Void visitDistributeResultOperator(DistributeResultOperator 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()) {
@@ -297,6 +353,7 @@
 
     @Override
     public Void visitExtensionOperator(ExtensionOperator op, Void arg) throws AlgebricksException {
+        op.getDelegate().getUsedVariables(usedVariables);
         return null;
     }
 
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java
index 25f22e7..f66f99b 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/logical/visitors/VariableUtilities.java
@@ -61,14 +61,22 @@
             ITypingContext ctx) throws AlgebricksException {
         substituteVariables(op, v1, v2, true, ctx);
     }
-
+    
+    public static void substituteVariablesInDescendantsAndSelf(ILogicalOperator op, LogicalVariable v1,
+            LogicalVariable v2, ITypingContext ctx) throws AlgebricksException {
+        for (Mutable<ILogicalOperator> childOp : op.getInputs()) {
+            substituteVariablesInDescendantsAndSelf(childOp.getValue(), v1, v2, ctx);
+        }
+        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>();
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DistributeResultPOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DistributeResultPOperator.java
new file mode 100644
index 0000000..302d4d2
--- /dev/null
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/DistributeResultPOperator.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.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.DistributeResultOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.IOperatorSchema;
+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.api.dataflow.IOperatorDescriptor;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.job.JobSpecification;
+
+public class DistributeResultPOperator extends AbstractPhysicalOperator {
+
+    @Override
+    public PhysicalOperatorTag getOperatorTag() {
+        return PhysicalOperatorTag.DISTRIBUTE_RESULT;
+    }
+
+    @Override
+    public boolean isMicroOperator() {
+        return false;
+    }
+
+    @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) {
+        DistributeResultOperator write = (DistributeResultOperator) op;
+        IDataSink sink = write.getDataSink();
+        IPartitioningProperty pp = sink.getPartitioningProperty();
+        StructuralPropertiesVector[] r = new StructuralPropertiesVector[] { new StructuralPropertiesVector(pp, null) };
+        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 {
+        DistributeResultOperator resultOp = (DistributeResultOperator) op;
+        IMetadataProvider mp = context.getMetadataProvider();
+
+        JobSpecification spec = builder.getJobSpec();
+
+        int[] columns = new int[resultOp.getExpressions().size()];
+        int i = 0;
+        for (Mutable<ILogicalExpression> exprRef : resultOp.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 inputDesc = JobGenHelper.mkRecordDescriptor(
+                context.getTypeEnvironment(op.getInputs().get(0).getValue()), inputSchemas[0], context);
+
+        IPrinterFactory[] pf = JobGenHelper.mkPrinterFactories(inputSchemas[0], context.getTypeEnvironment(op),
+                context, columns);
+
+        Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> runtimeAndConstraints = mp.getResultHandleRuntime(
+                resultOp.getDataSink(), columns, pf, inputDesc, false, spec);
+
+        builder.contributeHyracksOperator(resultOp, runtimeAndConstraints.first);
+        builder.contributeAlgebricksPartitionConstraint(runtimeAndConstraints.first, runtimeAndConstraints.second);
+        ILogicalOperator src = resultOp.getInputs().get(0).getValue();
+        builder.contributeGraphEdge(src, 0, resultOp, 0);
+    }
+}
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java
index f3c9e5a..61d4880 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HashPartitionMergeExchangePOperator.java
@@ -158,5 +158,13 @@
                 comparatorFactories);
         return new Pair<IConnectorDescriptor, TargetConstraint>(conn, null);
     }
+    
+    public List<LogicalVariable> getPartitionFields() {
+        return partitionFields;
+    }
+    
+    public List<OrderColumn> getOrderColumns() {
+        return orderColumns;
+    }
 
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
index c737cc4..6da42b4 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/HybridHashJoinPOperator.java
@@ -32,14 +32,21 @@
 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.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.IBinaryComparator;
 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.IBinaryHashFunctionFamily;
 import edu.uci.ics.hyracks.api.dataflow.value.INullWriterFactory;
+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.dataflow.std.join.HybridHashJoinOperatorDescriptor;
+import edu.uci.ics.hyracks.dataflow.std.join.OptimizedHybridHashJoinOperatorDescriptor;
 
 public class HybridHashJoinPOperator extends AbstractHashJoinPOperator {
 
@@ -90,6 +97,8 @@
         IVariableTypeEnvironment env = context.getTypeEnvironment(op);
         IBinaryHashFunctionFactory[] hashFunFactories = JobGenHelper.variablesToBinaryHashFunctionFactories(
                 keysLeftBranch, env, context);
+        IBinaryHashFunctionFamily[] hashFunFamilies = JobGenHelper.variablesToBinaryHashFunctionFamilies(
+                keysLeftBranch, env, context);
         IBinaryComparatorFactory[] comparatorFactories = new IBinaryComparatorFactory[keysLeft.length];
         int i = 0;
         IBinaryComparatorFactoryProvider bcfp = context.getBinaryComparatorFactoryProvider();
@@ -97,33 +106,75 @@
             Object t = env.getVarType(v);
             comparatorFactories[i++] = bcfp.getBinaryComparatorFactory(t, true);
         }
-        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        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();
-                }
+
+        boolean optimizedHashJoin = true;
+        for (IBinaryHashFunctionFamily family : hashFunFamilies) {
+            if (family == null) {
+                optimizedHashJoin = false;
+                break;
             }
-        } catch (HyracksDataException e) {
-            throw new AlgebricksException(e);
+        }
+
+        if (!optimizedHashJoin) {
+            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);
+            }
+        } else {
+            try {
+                switch (kind) {
+                    case INNER: {
+                        opDesc = new OptimizedHybridHashJoinOperatorDescriptor(spec, getMemSizeInFrames(),
+                                maxInputBuildSizeInFrames, getFudgeFactor(), keysLeft, keysRight, hashFunFamilies,
+                                comparatorFactories, recDescriptor, new JoinMultiComparatorFactory(comparatorFactories,
+                                        keysLeft, keysRight), new JoinMultiComparatorFactory(comparatorFactories,
+                                        keysRight, keysLeft));
+                        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 OptimizedHybridHashJoinOperatorDescriptor(spec, getMemSizeInFrames(),
+                                maxInputBuildSizeInFrames, getFudgeFactor(), keysLeft, keysRight, hashFunFamilies,
+                                comparatorFactories, recDescriptor, new JoinMultiComparatorFactory(comparatorFactories,
+                                        keysLeft, keysRight), new JoinMultiComparatorFactory(comparatorFactories,
+                                        keysRight, keysLeft), true, nullWriterFactories);
+                        break;
+                    }
+                    default: {
+                        throw new NotImplementedException();
+                    }
+                }
+            } catch (HyracksDataException e) {
+                throw new AlgebricksException(e);
+            }
         }
         contributeOpDesc(builder, (AbstractLogicalOperator) op, opDesc);
 
@@ -140,3 +191,72 @@
     }
 
 }
+
+/**
+ * {@ ITuplePairComparatorFactory} implementation for optimized hybrid hash join.
+ */
+class JoinMultiComparatorFactory implements ITuplePairComparatorFactory {
+    private static final long serialVersionUID = 1L;
+
+    private final IBinaryComparatorFactory[] binaryComparatorFactories;
+    private final int[] keysLeft;
+    private final int[] keysRight;
+
+    public JoinMultiComparatorFactory(IBinaryComparatorFactory[] binaryComparatorFactory, int[] keysLeft,
+            int[] keysRight) {
+        this.binaryComparatorFactories = binaryComparatorFactory;
+        this.keysLeft = keysLeft;
+        this.keysRight = keysRight;
+    }
+
+    @Override
+    public ITuplePairComparator createTuplePairComparator(IHyracksTaskContext ctx) {
+        IBinaryComparator[] binaryComparators = new IBinaryComparator[binaryComparatorFactories.length];
+        for (int i = 0; i < binaryComparators.length; i++) {
+            binaryComparators[i] = binaryComparatorFactories[i].createBinaryComparator();
+        }
+        return new JoinMultiComparator(binaryComparators, keysLeft, keysRight);
+    }
+}
+
+/**
+ * {@ ITuplePairComparator} implementation for optimized hybrid hash join.
+ * The comparator applies multiple binary comparators, one for each key pairs
+ */
+class JoinMultiComparator implements ITuplePairComparator {
+    private final IBinaryComparator[] binaryComparators;
+    private final int[] keysLeft;
+    private final int[] keysRight;
+
+    public JoinMultiComparator(IBinaryComparator[] bComparator, int[] keysLeft, int[] keysRight) {
+        this.binaryComparators = bComparator;
+        this.keysLeft = keysLeft;
+        this.keysRight = keysRight;
+    }
+
+    @Override
+    public int compare(IFrameTupleAccessor accessor0, int tIndex0, IFrameTupleAccessor accessor1, int tIndex1) {
+        int tStart0 = accessor0.getTupleStartOffset(tIndex0);
+        int fStartOffset0 = accessor0.getFieldSlotsLength() + tStart0;
+
+        int tStart1 = accessor1.getTupleStartOffset(tIndex1);
+        int fStartOffset1 = accessor1.getFieldSlotsLength() + tStart1;
+
+        for (int i = 0; i < binaryComparators.length; i++) {
+            int fStart0 = accessor0.getFieldStartOffset(tIndex0, keysLeft[i]);
+            int fEnd0 = accessor0.getFieldEndOffset(tIndex0, keysLeft[i]);
+            int fLen0 = fEnd0 - fStart0;
+
+            int fStart1 = accessor1.getFieldStartOffset(tIndex1, keysRight[i]);
+            int fEnd1 = accessor1.getFieldEndOffset(tIndex1, keysRight[i]);
+            int fLen1 = fEnd1 - fStart1;
+
+            int c = binaryComparators[i].compare(accessor0.getBuffer().array(), fStart0 + fStartOffset0, fLen0,
+                    accessor1.getBuffer().array(), fStart1 + fStartOffset1, fLen1);
+            if (c != 0) {
+                return c;
+            }
+        }
+        return 0;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java
index 8cbd2d8..d153f90 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/NLJoinPOperator.java
@@ -44,6 +44,7 @@
 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.INullWriterFactory;
 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;
@@ -56,8 +57,8 @@
 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.
+ * Left input is broadcast and preserves its local properties. Right input can
+ * be partitioned in any way.
  */
 public class NLJoinPOperator extends AbstractJoinPOperator {
 
@@ -97,7 +98,7 @@
                 pp = pv1.getPartitioningProperty();
             }
         } else {
-        	pp = IPartitioningProperty.UNPARTITIONED;
+            pp = IPartitioningProperty.UNPARTITIONED;
         }
 
         List<ILocalStructuralProperty> localProps = new LinkedList<ILocalStructuralProperty>();
@@ -122,7 +123,8 @@
             IOperatorSchema propagatedSchema, IOperatorSchema[] inputSchemas, IOperatorSchema outerPlanSchema)
             throws AlgebricksException {
         AbstractBinaryJoinOperator join = (AbstractBinaryJoinOperator) op;
-        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op), propagatedSchema, context);
+        RecordDescriptor recDescriptor = JobGenHelper.mkRecordDescriptor(context.getTypeEnvironment(op),
+                propagatedSchema, context);
         IOperatorSchema[] conditionInputSchemas = new IOperatorSchema[1];
         conditionInputSchemas[0] = propagatedSchema;
         IExpressionRuntimeProvider expressionRuntimeProvider = context.getExpressionRuntimeProvider();
@@ -135,10 +137,19 @@
 
         switch (kind) {
             case INNER: {
-                opDesc = new NestedLoopJoinOperatorDescriptor(spec, comparatorFactory, recDescriptor, memSize);
+                opDesc = new NestedLoopJoinOperatorDescriptor(spec, comparatorFactory, recDescriptor, memSize, false,
+                        null);
                 break;
             }
-            case LEFT_OUTER:
+            case LEFT_OUTER: {
+                INullWriterFactory[] nullWriterFactories = new INullWriterFactory[inputSchemas[1].getSize()];
+                for (int j = 0; j < nullWriterFactories.length; j++) {
+                    nullWriterFactories[j] = context.getNullWriterFactory();
+                }
+                opDesc = new NestedLoopJoinOperatorDescriptor(spec, comparatorFactory, recDescriptor, memSize, true,
+                        nullWriterFactories);
+                break;
+            }
             default: {
                 throw new NotImplementedException();
             }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java
index 7e3c935..8875f6c 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/operators/physical/RangePartitionPOperator.java
@@ -16,6 +16,7 @@
 
 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.exceptions.NotImplementedException;
@@ -69,5 +70,9 @@
             ILogicalOperator op, IOperatorSchema opSchema, JobGenContext context) throws AlgebricksException {
         throw new NotImplementedException();
     }
+    
+    public List<OrderColumn> getPartitioningFields() {
+        return partitioningFields;
+    }
 
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java
index a94c78e..fc0c433 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/prettyprint/LogicalOperatorPrettyPrintVisitor.java
@@ -30,8 +30,10 @@
 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.DistributeResultOperator;
 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;
@@ -48,7 +50,6 @@
 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;
@@ -164,6 +165,13 @@
     }
 
     @Override
+    public String visitDistributeResultOperator(DistributeResultOperator op, Integer indent) {
+        StringBuilder buffer = new StringBuilder();
+        addIndent(buffer, indent).append("distribute result ").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 ")
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java
index 6b5949e..23dac2a 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/algebra/visitors/ILogicalOperatorVisitor.java
@@ -20,8 +20,10 @@
 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.DistributeResultOperator;
 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;
@@ -37,7 +39,6 @@
 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;
@@ -97,6 +98,8 @@
 
     public R visitWriteOperator(WriteOperator op, T arg) throws AlgebricksException;
 
+    public R visitDistributeResultOperator(DistributeResultOperator op, T arg) throws AlgebricksException;
+
     public R visitWriteResultOperator(WriteResultOperator op, T arg) throws AlgebricksException;
 
     public R visitInsertDeleteOperator(InsertDeleteOperator op, T tag) throws AlgebricksException;
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
index 22a1a81..365d1a5 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenContext.java
@@ -34,6 +34,7 @@
 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.IBinaryHashFunctionFamilyProvider;
 import edu.uci.ics.hyracks.algebricks.data.IBinaryIntegerInspectorFactory;
 import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
 import edu.uci.ics.hyracks.algebricks.data.IPrinterFactoryProvider;
@@ -42,151 +43,167 @@
 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;
+	private final IOperatorSchema outerFlowSchema;
+	private final Map<ILogicalOperator, IOperatorSchema> schemaMap = new HashMap<ILogicalOperator, IOperatorSchema>();
+	private final ISerializerDeserializerProvider serializerDeserializerProvider;
+	private final IBinaryHashFunctionFactoryProvider hashFunctionFactoryProvider;
+	private final IBinaryHashFunctionFamilyProvider hashFunctionFamilyProvider;
+	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 JobGenContext(
+			IOperatorSchema outerFlowSchema,
+			IMetadataProvider<?, ?> metadataProvider,
+			Object appContext,
+			ISerializerDeserializerProvider serializerDeserializerProvider,
+			IBinaryHashFunctionFactoryProvider hashFunctionFactoryProvider,
+			IBinaryHashFunctionFamilyProvider hashFunctionFamilyProvider,
+			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.hashFunctionFamilyProvider = hashFunctionFamilyProvider;
+		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 IOperatorSchema getOuterFlowSchema() {
+		return outerFlowSchema;
+	}
 
-    public AlgebricksPartitionConstraint getClusterLocations() {
-        return clusterLocations;
-    }
+	public AlgebricksPartitionConstraint getClusterLocations() {
+		return clusterLocations;
+	}
 
-    public IMetadataProvider<?, ?> getMetadataProvider() {
-        return metadataProvider;
-    }
+	public IMetadataProvider<?, ?> getMetadataProvider() {
+		return metadataProvider;
+	}
 
-    public Object getAppContext() {
-        return appContext;
-    }
+	public Object getAppContext() {
+		return appContext;
+	}
 
-    public ISerializerDeserializerProvider getSerializerDeserializerProvider() {
-        return serializerDeserializerProvider;
-    }
+	public ISerializerDeserializerProvider getSerializerDeserializerProvider() {
+		return serializerDeserializerProvider;
+	}
 
-    public IBinaryHashFunctionFactoryProvider getBinaryHashFunctionFactoryProvider() {
-        return hashFunctionFactoryProvider;
-    }
+	public IBinaryHashFunctionFactoryProvider getBinaryHashFunctionFactoryProvider() {
+		return hashFunctionFactoryProvider;
+	}
 
-    public IBinaryComparatorFactoryProvider getBinaryComparatorFactoryProvider() {
-        return comparatorFactoryProvider;
-    }
+	public IBinaryHashFunctionFamilyProvider getBinaryHashFunctionFamilyProvider() {
+		return hashFunctionFamilyProvider;
+	}
 
-    public ITypeTraitProvider getTypeTraitProvider() {
-        return typeTraitProvider;
-    }
+	public IBinaryComparatorFactoryProvider getBinaryComparatorFactoryProvider() {
+		return comparatorFactoryProvider;
+	}
 
-    public IBinaryBooleanInspectorFactory getBinaryBooleanInspectorFactory() {
-        return booleanInspectorFactory;
-    }
+	public ITypeTraitProvider getTypeTraitProvider() {
+		return typeTraitProvider;
+	}
 
-    public IBinaryIntegerInspectorFactory getBinaryIntegerInspectorFactory() {
-        return integerInspectorFactory;
-    }
+	public IBinaryBooleanInspectorFactory getBinaryBooleanInspectorFactory() {
+		return booleanInspectorFactory;
+	}
 
-    public IPrinterFactoryProvider getPrinterFactoryProvider() {
-        return printerFactoryProvider;
-    }
+	public IBinaryIntegerInspectorFactory getBinaryIntegerInspectorFactory() {
+		return integerInspectorFactory;
+	}
 
-    public IExpressionRuntimeProvider getExpressionRuntimeProvider() {
-        return expressionRuntimeProvider;
-    }
+	public IPrinterFactoryProvider getPrinterFactoryProvider() {
+		return printerFactoryProvider;
+	}
 
-    public IOperatorSchema getSchema(ILogicalOperator op) {
-        return schemaMap.get(op);
-    }
+	public IExpressionRuntimeProvider getExpressionRuntimeProvider() {
+		return expressionRuntimeProvider;
+	}
 
-    public void putSchema(ILogicalOperator op, IOperatorSchema schema) {
-        schemaMap.put(op, schema);
-    }
+	public IOperatorSchema getSchema(ILogicalOperator op) {
+		return schemaMap.get(op);
+	}
 
-    public LogicalVariable createNewVar() {
-        varCounter++;
-        LogicalVariable var = new LogicalVariable(-varCounter);
-        return var;
-    }
+	public void putSchema(ILogicalOperator op, IOperatorSchema schema) {
+		schemaMap.put(op, schema);
+	}
 
-    public Object getType(ILogicalExpression expr, IVariableTypeEnvironment env) throws AlgebricksException {
-        return expressionTypeComputer.getType(expr, typingContext.getMetadataProvider(), env);
-    }
+	public LogicalVariable createNewVar() {
+		varCounter++;
+		LogicalVariable var = new LogicalVariable(-varCounter);
+		return var;
+	}
 
-    public INullWriterFactory getNullWriterFactory() {
-        return nullWriterFactory;
-    }
+	public Object getType(ILogicalExpression expr, IVariableTypeEnvironment env)
+			throws AlgebricksException {
+		return expressionTypeComputer.getType(expr,
+				typingContext.getMetadataProvider(), env);
+	}
 
-    public INormalizedKeyComputerFactoryProvider getNormalizedKeyComputerFactoryProvider() {
-        return normalizedKeyComputerFactoryProvider;
-    }
+	public INullWriterFactory getNullWriterFactory() {
+		return nullWriterFactory;
+	}
 
-    public IExpressionEvalSizeComputer getExpressionEvalSizeComputer() {
-        return expressionEvalSizeComputer;
-    }
+	public INormalizedKeyComputerFactoryProvider getNormalizedKeyComputerFactoryProvider() {
+		return normalizedKeyComputerFactoryProvider;
+	}
 
-    public int getFrameSize() {
-        return frameSize;
-    }
+	public IExpressionEvalSizeComputer getExpressionEvalSizeComputer() {
+		return expressionEvalSizeComputer;
+	}
 
-    public IPartialAggregationTypeComputer getPartialAggregationTypeComputer() {
-        return partialAggregationTypeComputer;
-    }
+	public int getFrameSize() {
+		return frameSize;
+	}
 
-    public IVariableTypeEnvironment getTypeEnvironment(ILogicalOperator op) {
-        return typingContext.getOutputTypeEnvironment(op);
-    }
+	public IPartialAggregationTypeComputer getPartialAggregationTypeComputer() {
+		return partialAggregationTypeComputer;
+	}
+
+	public IVariableTypeEnvironment getTypeEnvironment(ILogicalOperator op) {
+		return typingContext.getOutputTypeEnvironment(op);
+	}
 
 }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java
index 790fb93..530d19c 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/JobGenHelper.java
@@ -24,6 +24,7 @@
 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.IBinaryHashFunctionFamilyProvider;
 import edu.uci.ics.hyracks.algebricks.data.INormalizedKeyComputerFactoryProvider;
 import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
 import edu.uci.ics.hyracks.algebricks.data.IPrinterFactoryProvider;
@@ -31,6 +32,7 @@
 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.IBinaryHashFunctionFamily;
 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;
@@ -42,8 +44,8 @@
 
     @SuppressWarnings("rawtypes")
     public static RecordDescriptor mkRecordDescriptor(IVariableTypeEnvironment env, IOperatorSchema opSchema,
-            JobGenContext context) throws AlgebricksException {        
-		ISerializerDeserializer[] fields = new ISerializerDeserializer[opSchema.getSize()];
+            JobGenContext context) throws AlgebricksException {
+        ISerializerDeserializer[] fields = new ISerializerDeserializer[opSchema.getSize()];
         ITypeTraits[] typeTraits = new ITypeTraits[opSchema.getSize()];
         ISerializerDeserializerProvider sdp = context.getSerializerDeserializerProvider();
         ITypeTraitProvider ttp = context.getTypeTraitProvider();
@@ -59,7 +61,7 @@
         }
         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];
@@ -94,7 +96,20 @@
         }
         return funFactories;
     }
-    
+
+    public static IBinaryHashFunctionFamily[] variablesToBinaryHashFunctionFamilies(
+            Collection<LogicalVariable> varLogical, IVariableTypeEnvironment env, JobGenContext context)
+            throws AlgebricksException {
+        IBinaryHashFunctionFamily[] funFamilies = new IBinaryHashFunctionFamily[varLogical.size()];
+        int i = 0;
+        IBinaryHashFunctionFamilyProvider bhffProvider = context.getBinaryHashFunctionFamilyProvider();
+        for (LogicalVariable var : varLogical) {
+            Object type = env.getVarType(var);
+            funFamilies[i++] = bhffProvider.getBinaryHashFunctionFamily(type);
+        }
+        return funFamilies;
+    }
+
     public static IBinaryComparatorFactory[] variablesToAscBinaryComparatorFactories(
             Collection<LogicalVariable> varLogical, IVariableTypeEnvironment env, JobGenContext context)
             throws AlgebricksException {
@@ -107,15 +122,14 @@
         }
         return compFactories;
     }
-    
-    public static IBinaryComparatorFactory[] variablesToAscBinaryComparatorFactories(
-            List<LogicalVariable> varLogical, int start, int size, IVariableTypeEnvironment env, JobGenContext context)
-            throws AlgebricksException {
+
+    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);
+            Object type = env.getVarType(varLogical.get(start + i));
+            compFactories[i] = bcfProvider.getBinaryComparatorFactory(type, true);
         }
         return compFactories;
     }
@@ -144,15 +158,14 @@
         }
         return typeTraits;
     }
-    
-    public static ITypeTraits[] variablesToTypeTraits(
-            List<LogicalVariable> varLogical, int start, int size, IVariableTypeEnvironment env, JobGenContext context)
-            throws AlgebricksException {
+
+    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);
+            Object type = env.getVarType(varLogical.get(start + i));
+            typeTraits[i] = typeTraitProvider.getTypeTrait(type);
         }
         return typeTraits;
     }
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java
index bbe8fb3..63a6852 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/jobgen/impl/PlanCompiler.java
@@ -54,6 +54,8 @@
         operatorVisitedToParents.clear();
         builder.buildSpec(rootOps);
         spec.setConnectorPolicyAssignmentPolicy(new ConnectorPolicyAssignmentPolicy());
+        // Do not do activity cluster planning because it is slow on large clusters
+        spec.setUseConnectorPolicyForScheduling(false);
         return spec;
     }
 
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java
index 7c63e01..738fc7f 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/AlgebricksOptimizationContext.java
@@ -135,6 +135,7 @@
     /*
      * returns true if op1 and op2 have already been compared
      */
+    @Override
     public boolean checkAndAddToAlreadyCompared(ILogicalOperator op1, ILogicalOperator op2) {
         HashSet<ILogicalOperator> ops = alreadyCompared.get(op1);
         if (ops == null) {
@@ -151,6 +152,11 @@
             }
         }
     }
+    
+    @Override
+    public void removeFromAlreadyCompared(ILogicalOperator op1) {
+        alreadyCompared.remove(op1);
+    }
 
     public void addNotToBeInlinedVar(LogicalVariable var) {
         notToBeInlinedVars.add(var);
diff --git a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
index 9ce910b..fc6c198 100644
--- a/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
+++ b/fullstack/algebricks/algebricks-core/src/main/java/edu/uci/ics/hyracks/algebricks/core/rewriter/base/PhysicalOptimizationConfig.java
@@ -17,8 +17,8 @@
     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));
+        setInt(MAX_FRAMES_EXTERNAL_SORT, (int) (((long) 32 * MB) / frameSize));
+        setInt(MAX_FRAMES_EXTERNAL_GROUP_BY, (int) (((long) 32 * MB) / frameSize));
 
         // use http://www.rsok.com/~jrm/printprimes.html to find prime numbers
         setInt(DEFAULT_HASH_GROUP_TABLE_SIZE, 10485767);
diff --git a/fullstack/algebricks/algebricks-data/pom.xml b/fullstack/algebricks/algebricks-data/pom.xml
index 3d927d9..9536416 100644
--- a/fullstack/algebricks/algebricks-data/pom.xml
+++ b/fullstack/algebricks/algebricks-data/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IBinaryHashFunctionFamilyProvider.java b/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IBinaryHashFunctionFamilyProvider.java
new file mode 100644
index 0000000..8a992b3
--- /dev/null
+++ b/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IBinaryHashFunctionFamilyProvider.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.data;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFamily;
+
+public interface IBinaryHashFunctionFamilyProvider {
+
+	public IBinaryHashFunctionFamily getBinaryHashFunctionFamily(Object type)
+			throws AlgebricksException;
+}
diff --git a/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IResultSerializerFactoryProvider.java b/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IResultSerializerFactoryProvider.java
new file mode 100644
index 0000000..5e62612
--- /dev/null
+++ b/fullstack/algebricks/algebricks-data/src/main/java/edu/uci/ics/hyracks/algebricks/data/IResultSerializerFactoryProvider.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.data;
+
+import java.io.Serializable;
+
+import edu.uci.ics.hyracks.api.dataflow.value.IResultSerializerFactory;
+
+public interface IResultSerializerFactoryProvider extends Serializable {
+    /**
+     * Returns a result serializer factory
+     * 
+     * @param fields
+     *            - A position of the fields in the order it should be written in the output.
+     * @param printerFactories
+     *            - A printer factory array to print the tuple containing different fields.
+     * @param writerFactory
+     *            - A writer factory to write the serialized data to the print stream.
+     * @param inputRecordDesc
+     *            - The record descriptor describing the input frame to be serialized.
+     * @return A new instance of result serialized appender.
+     */
+    public IResultSerializerFactory getAqlResultSerializerFactoryProvider(int[] fields,
+            IPrinterFactory[] printerFactories, IAWriterFactory writerFactory);
+}
diff --git a/fullstack/algebricks/algebricks-examples/piglet-example/pom.xml b/fullstack/algebricks/algebricks-examples/piglet-example/pom.xml
index 954938a..ca7467b 100644
--- a/fullstack/algebricks/algebricks-examples/piglet-example/pom.xml
+++ b/fullstack/algebricks/algebricks-examples/piglet-example/pom.xml
@@ -16,8 +16,9 @@
 				<artifactId>maven-compiler-plugin</artifactId>
 				<version>2.0.2</version>
 				<configuration>
-					<source>1.6</source>
-					<target>1.6</target>
+					<source>1.7</source>
+					<target>1.7</target>
+					<fork>true</fork>
 				</configuration>
 			</plugin>
 			<plugin>
diff --git a/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/compiler/PigletCompiler.java b/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/compiler/PigletCompiler.java
index d105759..2981157 100644
--- a/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/compiler/PigletCompiler.java
+++ b/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/compiler/PigletCompiler.java
@@ -127,9 +127,9 @@
             }
         });
         builder.setTypeTraitProvider(new ITypeTraitProvider() {
-			public ITypeTraits getTypeTrait(Object type) {
-				return null;
-			}
+            public ITypeTraits getTypeTrait(Object type) {
+                return null;
+            }
         });
         builder.setPrinterProvider(PigletPrinterFactoryProvider.INSTANCE);
         builder.setExpressionRuntimeProvider(new LogicalExpressionJobGenToExpressionRuntimeProviderAdapter(
diff --git a/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/metadata/PigletMetadataProvider.java b/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/metadata/PigletMetadataProvider.java
index d678803..15b290e 100644
--- a/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/metadata/PigletMetadataProvider.java
+++ b/fullstack/algebricks/algebricks-examples/piglet-example/src/main/java/edu/uci/ics/hyracks/algebricks/examples/piglet/metadata/PigletMetadataProvider.java
@@ -145,6 +145,13 @@
     }
 
     @Override
+    public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getResultHandleRuntime(IDataSink sink,
+            int[] printColumns, IPrinterFactory[] printerFactories, RecordDescriptor inputDesc, boolean ordered,
+            JobSpecification spec) throws AlgebricksException {
+        return null;
+    }
+
+    @Override
     public Pair<IOperatorDescriptor, AlgebricksPartitionConstraint> getWriteResultRuntime(
             IDataSource<String> dataSource, IOperatorSchema propagatedSchema, List<LogicalVariable> keys,
             LogicalVariable payLoadVar, JobGenContext context, JobSpecification jobSpec) throws AlgebricksException {
diff --git a/fullstack/algebricks/algebricks-rewriter/pom.xml b/fullstack/algebricks/algebricks-rewriter/pom.xml
index 41979d3..7968773 100644
--- a/fullstack/algebricks/algebricks-rewriter/pom.xml
+++ b/fullstack/algebricks/algebricks-rewriter/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexJoinInferenceRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexJoinInferenceRule.java
index 4f6699a..3daf85d 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexJoinInferenceRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexJoinInferenceRule.java
@@ -69,7 +69,7 @@
         VariableUtilities.getUsedVariables(op, varsUsedInUnnest);
 
         HashSet<LogicalVariable> producedInSubplan = new HashSet<LogicalVariable>();
-        VariableUtilities.getLiveVariables(subplan, producedInSubplan);
+        VariableUtilities.getProducedVariables(subplan, producedInSubplan);
 
         if (!producedInSubplan.containsAll(varsUsedInUnnest)) {
             return false;
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexUnnestToProductRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexUnnestToProductRule.java
index 4521d1a..fa5000e 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexUnnestToProductRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ComplexUnnestToProductRule.java
@@ -149,9 +149,15 @@
             // Trivially joinable.
             return true;
         }
-        if (!belowSecondUnnest && op.getOperatorTag() == LogicalOperatorTag.SUBPLAN) {
-            // Bail on subplan.
-            return false;
+        if (!belowSecondUnnest) {
+            // Bail on the following operators.
+            switch (op.getOperatorTag()) {
+                case AGGREGATE:
+                case SUBPLAN:
+                case GROUP:
+                case UNNEST_MAP:
+                    return false;
+            }
         }
         switch (op.getOperatorTag()) {
             case UNNEST:
@@ -211,7 +217,8 @@
                 for (LogicalVariable producedVar : producedVars) {
                     if (outerUsedVars.contains(producedVar)) {
                         outerMatches++;
-                    } else if (innerUsedVars.contains(producedVar)) {
+                    }
+                    if (innerUsedVars.contains(producedVar)) {
                         innerMatches++;
                     }
                 }
@@ -221,24 +228,30 @@
                     // All produced vars used by outer partition.
                     outerOps.add(op);
                     targetUsedVars = outerUsedVars;
-                } else if (innerMatches == producedVars.size() && !producedVars.isEmpty()) {
+                }
+                if (innerMatches == producedVars.size() && !producedVars.isEmpty()) {
                     // All produced vars used by inner partition.
                     innerOps.add(op);
                     targetUsedVars = innerUsedVars;
-                } else if (innerMatches == 0 && outerMatches == 0) {
+                }
+                if (innerMatches == 0 && outerMatches == 0) {
                     // Op produces variables that are not used in the part of the plan we've seen (or it doesn't produce any vars).
                     // Try to figure out where it belongs by analyzing the used variables.
                     List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>();
                     VariableUtilities.getUsedVariables(op, usedVars);
                     for (LogicalVariable usedVar : usedVars) {
+                        boolean canBreak = false;
                         if (outerUsedVars.contains(usedVar)) {
                             outerOps.add(op);
                             targetUsedVars = outerUsedVars;
-                            break;
+                            canBreak = true;
                         }
                         if (innerUsedVars.contains(usedVar)) {
                             innerOps.add(op);
                             targetUsedVars = innerUsedVars;
+                            canBreak = true;
+                        }
+                        if (canBreak) {
                             break;
                         }
                     }
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ExtractCommonExpressionsRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ExtractCommonExpressionsRule.java
new file mode 100644
index 0000000..f017e0f
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/ExtractCommonExpressionsRule.java
@@ -0,0 +1,439 @@
+/*
+ * 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.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+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.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.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.AbstractLogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
+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.functions.FunctionIdentifier;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.SelectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Factors out common sub-expressions by assigning them to a variables, and replacing the common sub-expressions with references to those variables.
+ *
+ * Preconditions/Assumptions:
+ * Assumes no projects are in the plan. This rule ignores variable reference expressions and constants (other rules deal with those separately).
+ * 
+ * Postconditions/Examples:
+ * Plan with extracted sub-expressions. Generates one assign operator per extracted expression.
+ * 
+ * Example 1 - Simple Arithmetic Example (simplified)
+ * 
+ * Before plan:
+ * assign [$$1] <- [5 + 6 - 10]
+ *   assign [$$0] <- [5 + 6 + 30]
+ * 
+ * After plan:
+ * assign [$$1] <- [$$5 - 10]
+ *   assign [$$0] <- [$$5 + 30]
+ *     assign [$$5] <- [5 + 6]
+ * 
+ * Example 2 - Cleaning up 'Distinct By' (simplified)
+ * 
+ * Before plan: (notice how $$0 is not live after the distinct)
+ * assign [$$3] <- [field-access($$0, 1)]
+ *   distinct ([%0->$$5])
+ *     assign [$$5] <- [field-access($$0, 1)]
+ *       unnest $$0 <- [scan-dataset]
+ * 
+ * After plan: (notice how the issue of $$0 is fixed)
+ * assign [$$3] <- [$$5]
+ *   distinct ([$$5])
+ *     assign [$$5] <- [field-access($$0, 1)]
+ *       unnest $$0 <- [scan-dataset]
+ * 
+ * Example 3 - Pulling Common Expressions Above Joins (simplified)
+ * 
+ * Before plan:
+ * assign [$$9] <- funcZ(funcY($$8))
+ *   join (funcX(funcY($$8)))
+ * 
+ * After plan:
+ * assign [$$9] <- funcZ($$10))
+ *   select (funcX($$10))
+ *     assign [$$10] <- [funcY($$8)]
+ *       join (TRUE)
+ */
+public class ExtractCommonExpressionsRule implements IAlgebraicRewriteRule {
+
+    private final List<ILogicalExpression> originalAssignExprs = new ArrayList<ILogicalExpression>();
+    
+    private final CommonExpressionSubstitutionVisitor substVisitor = new CommonExpressionSubstitutionVisitor();
+    private final Map<ILogicalExpression, ExprEquivalenceClass> exprEqClassMap = new HashMap<ILogicalExpression, ExprEquivalenceClass>();
+    
+    // Set of operators for which common subexpression elimination should not be performed.
+    private static final Set<LogicalOperatorTag> ignoreOps = new HashSet<LogicalOperatorTag>();
+    static {
+        ignoreOps.add(LogicalOperatorTag.UNNEST);
+        ignoreOps.add(LogicalOperatorTag.UNNEST_MAP);
+        ignoreOps.add(LogicalOperatorTag.ORDER);
+        ignoreOps.add(LogicalOperatorTag.PROJECT);
+        ignoreOps.add(LogicalOperatorTag.AGGREGATE);
+        ignoreOps.add(LogicalOperatorTag.RUNNINGAGGREGATE);
+    }
+    
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        exprEqClassMap.clear();
+        substVisitor.setContext(context);
+        boolean modified = removeCommonExpressions(opRef, context);
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(opRef.getValue());
+        }
+        return modified;
+    }
+
+    private void updateEquivalenceClassMap(LogicalVariable lhs, Mutable<ILogicalExpression> rhsExprRef, ILogicalExpression rhsExpr, ILogicalOperator op) {
+        ExprEquivalenceClass exprEqClass = exprEqClassMap.get(rhsExpr);
+        if (exprEqClass == null) {
+            exprEqClass = new ExprEquivalenceClass(op, rhsExprRef);
+            exprEqClassMap.put(rhsExpr, exprEqClass);
+        }
+        exprEqClass.setVariable(lhs);
+    }
+
+    private boolean removeCommonExpressions(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        if (context.checkIfInDontApplySet(this, opRef.getValue())) {
+            return false;
+        }
+        
+        boolean modified = false;
+        // Recurse into children.
+        for (Mutable<ILogicalOperator> inputOpRef : op.getInputs()) {
+            if (removeCommonExpressions(inputOpRef, context)) {
+                modified = true;
+            }
+        }
+        
+        // TODO: Deal with replicate properly. Currently, we just clear the expr equivalence map, since we want to avoid incorrect expression replacement
+        // (the resulting new variables should be assigned live below a replicate).
+        if (op.getOperatorTag() == LogicalOperatorTag.REPLICATE) {
+            exprEqClassMap.clear();
+            return modified;
+        }
+        // Exclude these operators.
+        if (ignoreOps.contains(op.getOperatorTag())) {
+            return modified;
+        }
+        
+        // Remember a copy of the original assign expressions, so we can add them to the equivalence class map
+        // after replacing expressions within the assign operator itself.
+        if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
+            AssignOperator assignOp = (AssignOperator) op;
+            originalAssignExprs.clear();
+            int numVars = assignOp.getVariables().size();
+            for (int i = 0; i < numVars; i++) {
+                Mutable<ILogicalExpression> exprRef = assignOp.getExpressions().get(i);
+                ILogicalExpression expr = exprRef.getValue();
+                originalAssignExprs.add(expr.cloneExpression());
+            }
+        }
+        
+        // Perform common subexpression elimination.
+        substVisitor.setOperator(op);
+        if (op.acceptExpressionTransform(substVisitor)) {
+            modified = true;
+        }
+        
+        // Update equivalence class map.
+        if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
+            AssignOperator assignOp = (AssignOperator) op;
+            int numVars = assignOp.getVariables().size();
+            for (int i = 0; i < numVars; i++) {
+                Mutable<ILogicalExpression> exprRef = assignOp.getExpressions().get(i);
+                ILogicalExpression expr = exprRef.getValue();
+                if (expr.getExpressionTag() == LogicalExpressionTag.VARIABLE
+                        || expr.getExpressionTag() == LogicalExpressionTag.CONSTANT) {
+                    continue;
+                }
+                // Update equivalence class map.
+                LogicalVariable lhs = assignOp.getVariables().get(i);
+                updateEquivalenceClassMap(lhs, exprRef, exprRef.getValue(), op);
+                
+                // Update equivalence class map with original assign expression.
+                updateEquivalenceClassMap(lhs, exprRef, originalAssignExprs.get(i), op);
+            }
+        }
+
+        // TODO: For now do not perform replacement in nested plans
+        // due to the complication of figuring out whether the firstOp in an equivalence class is within a subplan, 
+        // and the resulting variable will not be visible to the outside.
+        // Since subplans should be eliminated in most cases, this behavior is acceptable for now.
+        /*
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans opWithNestedPlan = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan nestedPlan : opWithNestedPlan.getNestedPlans()) {
+                for (Mutable<ILogicalOperator> rootRef : nestedPlan.getRoots()) {
+                    if (removeCommonExpressions(rootRef, context)) {
+                        modified = true;
+                    }
+                }
+            }
+        }
+        */
+
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(op);
+            context.addToDontApplySet(this, op);
+        }
+        return modified;
+    }
+
+    private class CommonExpressionSubstitutionVisitor implements ILogicalExpressionReferenceTransform {
+                
+        private final Set<LogicalVariable> liveVars = new HashSet<LogicalVariable>();
+        private final List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>();
+        private IOptimizationContext context;
+        private ILogicalOperator op;        
+        
+        public void setContext(IOptimizationContext context) {
+            this.context = context;
+        }
+        
+        public void setOperator(ILogicalOperator op) throws AlgebricksException {
+            this.op = op;
+            liveVars.clear();
+            usedVars.clear();
+        }
+        
+        @Override
+        public boolean transform(Mutable<ILogicalExpression> exprRef) throws AlgebricksException {
+            if (liveVars.isEmpty() && usedVars.isEmpty()) {
+                VariableUtilities.getLiveVariables(op, liveVars);
+                VariableUtilities.getUsedVariables(op, usedVars);
+            }
+            
+            AbstractLogicalExpression expr = (AbstractLogicalExpression) exprRef.getValue();
+            boolean modified = false;
+            ExprEquivalenceClass exprEqClass = exprEqClassMap.get(expr);
+            if (exprEqClass != null) {
+                // Replace common subexpression with existing variable. 
+                if (exprEqClass.variableIsSet()) {
+                    // Check if the replacing variable is live at this op.
+                    // However, if the op is already using variables that are not live, then a replacement may enable fixing the plan.
+                    // This behavior is necessary to, e.g., properly deal with distinct by.
+                    // Also just replace the expr if we are replacing common exprs from within the same operator.
+                    if (liveVars.contains(exprEqClass.getVariable()) || !liveVars.containsAll(usedVars)
+                            || op == exprEqClass.getFirstOperator()) {
+                        exprRef.setValue(new VariableReferenceExpression(exprEqClass.getVariable()));
+                        // Do not descend into children since this expr has been completely replaced.
+                        return true;
+                    }
+                } else {
+                    if (assignCommonExpression(exprEqClass, expr)) {
+                        exprRef.setValue(new VariableReferenceExpression(exprEqClass.getVariable()));
+                        // Do not descend into children since this expr has been completely replaced.
+                        return true;
+                    }
+                }
+            } else {
+                if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE
+                        && expr.getExpressionTag() != LogicalExpressionTag.CONSTANT) {
+                    exprEqClass = new ExprEquivalenceClass(op, exprRef);
+                    exprEqClassMap.put(expr, exprEqClass);
+                }
+            }
+            
+            // Descend into function arguments.
+            if (expr.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
+                AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
+                for (Mutable<ILogicalExpression> arg : funcExpr.getArguments()) {
+                    if (transform(arg)) {
+                        modified = true;
+                    }
+                }
+            }
+            return modified;
+        }
+        
+        private boolean assignCommonExpression(ExprEquivalenceClass exprEqClass, ILogicalExpression expr) throws AlgebricksException {
+            AbstractLogicalOperator firstOp = (AbstractLogicalOperator) exprEqClass.getFirstOperator();
+            Mutable<ILogicalExpression> firstExprRef = exprEqClass.getFirstExpression();
+            if (firstOp.getOperatorTag() == LogicalOperatorTag.INNERJOIN || firstOp.getOperatorTag() == LogicalOperatorTag.LEFTOUTERJOIN) {
+                // Do not extract common expressions from within the same join operator.
+                if (firstOp == op) {
+                    return false;
+                }
+                AbstractBinaryJoinOperator joinOp = (AbstractBinaryJoinOperator) firstOp;
+                Mutable<ILogicalExpression> joinCond = joinOp.getCondition();                
+                ILogicalExpression enclosingExpr = getEnclosingExpression(joinCond, firstExprRef.getValue());
+                if (enclosingExpr == null) {
+                    // No viable enclosing expression that we can pull out from the join.
+                    return false;
+                }
+                // Place a Select operator beneath op that contains the enclosing expression.
+                SelectOperator selectOp = new SelectOperator(new MutableObject<ILogicalExpression>(enclosingExpr));
+                selectOp.getInputs().add(new MutableObject<ILogicalOperator>(op.getInputs().get(0).getValue()));
+                op.getInputs().get(0).setValue(selectOp);
+                // Set firstOp to be the select below op, since we want to assign the common subexpr there.
+                firstOp = (AbstractLogicalOperator) selectOp;
+            } else if (firstOp.getInputs().size() > 1) { 
+                // Bail for any non-join operator with multiple inputs.
+                return false;
+            }                        
+            LogicalVariable newVar = context.newVar();
+            AssignOperator newAssign = new AssignOperator(newVar, new MutableObject<ILogicalExpression>(firstExprRef.getValue().cloneExpression()));            
+            // Place assign below firstOp.
+            newAssign.getInputs().add(new MutableObject<ILogicalOperator>(firstOp.getInputs().get(0).getValue()));
+            newAssign.setExecutionMode(firstOp.getExecutionMode());
+            firstOp.getInputs().get(0).setValue(newAssign);
+            // Replace original expr with variable reference, and set var in expression equivalence class.
+            firstExprRef.setValue(new VariableReferenceExpression(newVar));
+            exprEqClass.setVariable(newVar);
+            context.computeAndSetTypeEnvironmentForOperator(newAssign);
+            context.computeAndSetTypeEnvironmentForOperator(firstOp);
+            return true;
+        }
+
+        private ILogicalExpression getEnclosingExpression(Mutable<ILogicalExpression> conditionExprRef, ILogicalExpression commonSubExpr) {
+            ILogicalExpression conditionExpr = conditionExprRef.getValue();
+            if (conditionExpr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+                return null;
+            }
+            if (isEqJoinCondition(commonSubExpr)) {
+                // Do not eliminate the common expression if we could use it for an equi-join.
+                return null;
+            }
+            AbstractFunctionCallExpression conditionFuncExpr = (AbstractFunctionCallExpression) conditionExpr;
+            // Boolean expression that encloses the common subexpression.
+            ILogicalExpression enclosingBoolExpr = null;
+            // We are not dealing with arbitrarily nested and/or expressions here.
+            FunctionIdentifier funcIdent = conditionFuncExpr.getFunctionIdentifier();
+            if (funcIdent.equals(AlgebricksBuiltinFunctions.AND) || funcIdent.equals(AlgebricksBuiltinFunctions.OR)) {
+                Iterator<Mutable<ILogicalExpression>> argIter = conditionFuncExpr.getArguments().iterator();
+                while (argIter.hasNext()) {
+                    Mutable<ILogicalExpression> argRef = argIter.next();
+                    if (containsExpr(argRef.getValue(), commonSubExpr)) {
+                        enclosingBoolExpr = argRef.getValue();
+                        // Remove the enclosing expression from the argument list.
+                        // We are going to pull it out into a new select operator.
+                        argIter.remove();
+                        break;
+                    }
+                }
+                // If and/or only has a single argument left, pull it out and remove the and/or function.
+                if (conditionFuncExpr.getArguments().size() == 1) {
+                    conditionExprRef.setValue(conditionFuncExpr.getArguments().get(0).getValue());
+                }
+            } else {
+                if (!containsExpr(conditionExprRef.getValue(), commonSubExpr)) {
+                    return null;
+                }
+                enclosingBoolExpr = conditionFuncExpr;
+                // Replace the enclosing expression with TRUE.
+                conditionExprRef.setValue(ConstantExpression.TRUE);
+            }
+            return enclosingBoolExpr;
+        }
+    }
+    
+    private boolean containsExpr(ILogicalExpression expr, ILogicalExpression searchExpr) {
+        if (expr == searchExpr) {
+            return true;
+        }
+        if (expr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+            return false;
+        }
+        AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
+        for (Mutable<ILogicalExpression> argRef : funcExpr.getArguments()) {
+            if (containsExpr(argRef.getValue(), searchExpr)) {
+                return true;
+            }
+        }
+        return false;
+    }
+    
+    private boolean isEqJoinCondition(ILogicalExpression expr) {
+        AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
+        if (funcExpr.getFunctionIdentifier().equals(AlgebricksBuiltinFunctions.EQ)) {
+            ILogicalExpression arg1 = funcExpr.getArguments().get(0).getValue();
+            ILogicalExpression arg2 = funcExpr.getArguments().get(1).getValue();
+            if (arg1.getExpressionTag() == LogicalExpressionTag.VARIABLE
+                    && arg2.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
+                return true;
+            }
+        }
+        return false;
+    }
+    
+    private final class ExprEquivalenceClass {
+        // First operator in which expression is used.
+        private final ILogicalOperator firstOp;
+        
+        // Reference to expression in first op.
+        private final Mutable<ILogicalExpression> firstExprRef;
+        
+        // Variable that this expression has been assigned to.
+        private LogicalVariable var;
+        
+        public ExprEquivalenceClass(ILogicalOperator firstOp, Mutable<ILogicalExpression> firstExprRef) {
+            this.firstOp = firstOp;
+            this.firstExprRef = firstExprRef;
+        }
+        
+        public ILogicalOperator getFirstOperator() {
+            return firstOp;
+        }
+        
+        public Mutable<ILogicalExpression> getFirstExpression() {
+            return firstExprRef;
+        }
+        
+        public void setVariable(LogicalVariable var) {
+            this.var = var;
+        }
+        
+        public LogicalVariable getVariable() {
+            return var;
+        }
+        
+        public boolean variableIsSet() {
+            return var != null;
+        }
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineSingleReferenceVariablesRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineSingleReferenceVariablesRule.java
new file mode 100644
index 0000000..df8ddda
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineSingleReferenceVariablesRule.java
@@ -0,0 +1,94 @@
+/*
+ * 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.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+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.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.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+
+/**
+ * Inlines variables that are referenced exactly once.
+ * 
+ * Preconditions/Assumptions:
+ * Assumes no projects are in the plan.
+ * 
+ * Example assuming variable $$3 is referenced exactly once.
+ * 
+ * Before plan:
+ * select (funcA($$3))
+ *   ...
+ *     assign [$$3] <- [field-access($$0, 1)]
+ * 
+ * After plan:
+ * select (funcA(field-access($$0, 1))
+ *   ...
+ *     assign [] <- []
+ */
+public class InlineSingleReferenceVariablesRule extends InlineVariablesRule {
+
+    // Maps from variable to a list of operators using that variable.
+    protected Map<LogicalVariable, List<ILogicalOperator>> usedVarsMap = new HashMap<LogicalVariable, List<ILogicalOperator>>();
+    protected List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>();
+    
+    @Override
+    protected void prepare(IOptimizationContext context) {
+        super.prepare(context);
+        usedVarsMap.clear();
+        usedVars.clear();
+    }
+    
+    @Override
+    protected boolean performFinalAction() throws AlgebricksException {
+        boolean modified = false;
+        for (Map.Entry<LogicalVariable, List<ILogicalOperator>> entry : usedVarsMap.entrySet()) {
+            // Perform replacement only if variable is referenced a single time.
+            if (entry.getValue().size() == 1) {
+                ILogicalOperator op = entry.getValue().get(0);
+                if (!op.requiresVariableReferenceExpressions()) {
+                    inlineVisitor.setOperator(op);
+                    inlineVisitor.setTargetVariable(entry.getKey());
+                    if (op.acceptExpressionTransform(inlineVisitor)) {
+                        modified = true;
+                    }
+                    inlineVisitor.setTargetVariable(null);
+                }         
+            }
+        }
+        return modified;
+    }
+
+    @Override
+    protected boolean performBottomUpAction(AbstractLogicalOperator op) throws AlgebricksException {
+        usedVars.clear();
+        VariableUtilities.getUsedVariables(op, usedVars);
+        for (LogicalVariable var : usedVars) {
+            List<ILogicalOperator> opsUsingVar = usedVarsMap.get(var);
+            if (opsUsingVar == null) {
+                opsUsingVar = new ArrayList<ILogicalOperator>();
+                usedVarsMap.put(var, opsUsingVar);
+            }
+            opsUsingVar.add(op);
+        }
+        return false;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
index 8a79d81..7fed577 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
@@ -15,330 +15,231 @@
 package edu.uci.ics.hyracks.algebricks.rewriter.rules;
 
 import java.util.ArrayList;
-import java.util.Iterator;
-import java.util.LinkedList;
+import java.util.HashMap;
+import java.util.HashSet;
 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.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.AbstractLogicalExpression;
-import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
 import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
 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.AssignOperator;
-import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
-import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
 import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
-import edu.uci.ics.hyracks.algebricks.core.config.AlgebricksConfig;
 import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
 
+/**
+ * Replaces variable reference expressions with their assigned function-call expression where applicable
+ * (some variables are generated by datasources).
+ * Inlining variables may enable other optimizations by allowing selects and assigns to be moved
+ * (e.g., a select may be pushed into a join to enable an efficient physical join operator).
+ * 
+ * Preconditions/Assumptions:
+ * Assumes no projects are in the plan. Only inlines variables whose assigned expression is a function call 
+ * (i.e., this rule ignores right-hand side constants and other variable references expressions  
+ * 
+ * Postconditions/Examples:
+ * All qualifying variables have been inlined.
+ * 
+ * Example (simplified):
+ * 
+ * Before plan:
+ * select <- [$$1 < $$2 + $$0]
+ *   assign [$$2] <- [funcZ() + $$0]
+ *     assign [$$0, $$1] <- [funcX(), funcY()]
+ * 
+ * After plan:
+ * select <- [funcY() < funcZ() + funcX() + funcX()]
+ *   assign [$$2] <- [funcZ() + funcX()]
+ *     assign [$$0, $$1] <- [funcX(), funcY()]
+ */
 public class InlineVariablesRule implements IAlgebraicRewriteRule {
 
+    // Map of variables that could be replaced by their producing expression.
+    // Populated during the top-down sweep of the plan.
+    protected Map<LogicalVariable, ILogicalExpression> varAssignRhs = new HashMap<LogicalVariable, ILogicalExpression>();
+
+    // Visitor for replacing variable reference expressions with their originating expression.
+    protected InlineVariablesVisitor inlineVisitor = new InlineVariablesVisitor(varAssignRhs);
+    
+    // Set of FunctionIdentifiers that we should not inline.
+    protected Set<FunctionIdentifier> doNotInlineFuncs = new HashSet<FunctionIdentifier>();
+    
+    protected boolean hasRun = false;
+    
     @Override
     public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
         return false;
     }
 
     @Override
-    /**
-     * 
-     * Does one big DFS sweep over the plan.
-     * 
-     */
     public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        if (hasRun) {
+            return false;
+        }
         if (context.checkIfInDontApplySet(this, opRef.getValue())) {
             return false;
         }
-        VariableSubstitutionVisitor substVisitor = new VariableSubstitutionVisitor(false);
-        VariableSubstitutionVisitor substVisitorForWrites = new VariableSubstitutionVisitor(true);
-        substVisitor.setContext(context);
-        substVisitorForWrites.setContext(context);
-        Pair<Boolean, Boolean> bb = collectEqClassesAndRemoveRedundantOps(opRef, context, true,
-                new LinkedList<EquivalenceClass>(), substVisitor, substVisitorForWrites);
-        return bb.first;
+        prepare(context);
+        boolean modified = inlineVariables(opRef, context);
+        if (performFinalAction()) {
+            modified = true;
+        }
+        hasRun = true;
+        return modified;
+    }
+    
+    protected void prepare(IOptimizationContext context) {
+        varAssignRhs.clear();
+        inlineVisitor.setContext(context);
+    }
+    
+    protected boolean performBottomUpAction(AbstractLogicalOperator op) throws AlgebricksException {
+        // Only inline variables in operators that can deal with arbitrary expressions.
+        if (!op.requiresVariableReferenceExpressions()) {
+            inlineVisitor.setOperator(op);
+            return op.acceptExpressionTransform(inlineVisitor);
+        }
+        return false;
     }
 
-    private Pair<Boolean, Boolean> collectEqClassesAndRemoveRedundantOps(Mutable<ILogicalOperator> opRef,
-            IOptimizationContext context, boolean first, List<EquivalenceClass> equivClasses,
-            VariableSubstitutionVisitor substVisitor, VariableSubstitutionVisitor substVisitorForWrites)
+    protected boolean performFinalAction() throws AlgebricksException {
+        return false;
+    }
+    
+    protected boolean inlineVariables(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
             throws AlgebricksException {
         AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
-        // if (context.checkIfInDontApplySet(this, opRef.getValue())) {
-        // return false;
-        // }
-        if (op.getOperatorTag() == LogicalOperatorTag.UNNEST_MAP) {
-            return new Pair<Boolean, Boolean>(false, false);
-        }
-        boolean modified = false;
-        boolean ecChange = false;
-        int cnt = 0;
-        for (Mutable<ILogicalOperator> i : op.getInputs()) {
-            boolean isOuterInputBranch = op.getOperatorTag() == LogicalOperatorTag.LEFTOUTERJOIN && cnt == 1;
-            List<EquivalenceClass> eqc = isOuterInputBranch ? new LinkedList<EquivalenceClass>() : equivClasses;
-
-            Pair<Boolean, Boolean> bb = (collectEqClassesAndRemoveRedundantOps(i, context, false, eqc, substVisitor,
-                    substVisitorForWrites));
-
-            if (bb.first) {
-                modified = true;
-            }
-            if (bb.second) {
-                ecChange = true;
-            }
-
-            if (isOuterInputBranch) {
-                if (AlgebricksConfig.DEBUG) {
-                    AlgebricksConfig.ALGEBRICKS_LOGGER.finest("--- Equivalence classes for inner branch of outer op.: "
-                            + eqc + "\n");
-                }
-                for (EquivalenceClass ec : eqc) {
-                    if (!ec.representativeIsConst()) {
-                        equivClasses.add(ec);
-                    }
-                }
-            }
-
-            ++cnt;
-        }
-        if (op.hasNestedPlans()) {
-            AbstractOperatorWithNestedPlans n = (AbstractOperatorWithNestedPlans) op;
-            List<EquivalenceClass> eqc = equivClasses;
-            if (n.getOperatorTag() == LogicalOperatorTag.SUBPLAN) {
-                eqc = new LinkedList<EquivalenceClass>();
-            } else {
-                eqc = equivClasses;
-            }
-            for (ILogicalPlan p : n.getNestedPlans()) {
-                for (Mutable<ILogicalOperator> r : p.getRoots()) {
-                    Pair<Boolean, Boolean> bb = collectEqClassesAndRemoveRedundantOps(r, context, false, eqc,
-                            substVisitor, substVisitorForWrites);
-                    if (bb.first) {
-                        modified = true;
-                    }
-                    if (bb.second) {
-                        ecChange = true;
-                    }
-                }
-            }
-        }
-        // we assume a variable is assigned a value only once
+        
+        // Update mapping from variables to expressions during top-down traversal.
         if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
-            AssignOperator a = (AssignOperator) op;
-            ILogicalExpression rhs = a.getExpressions().get(0).getValue();
-            if (rhs.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
-                LogicalVariable varLeft = a.getVariables().get(0);
-                VariableReferenceExpression varRef = (VariableReferenceExpression) rhs;
-                LogicalVariable varRight = varRef.getVariableReference();
-
-                EquivalenceClass ecRight = findEquivClass(varRight, equivClasses);
-                if (ecRight != null) {
-                    ecRight.addMember(varLeft);
-                } else {
-                    List<LogicalVariable> m = new LinkedList<LogicalVariable>();
-                    m.add(varRight);
-                    m.add(varLeft);
-                    EquivalenceClass ec = new EquivalenceClass(m, varRight);
-                    equivClasses.add(ec);
-                    if (AlgebricksConfig.DEBUG) {
-                        AlgebricksConfig.ALGEBRICKS_LOGGER.finest("--- New equivalence class: " + ec + "\n");
+            AssignOperator assignOp = (AssignOperator) op;
+            List<LogicalVariable> vars = assignOp.getVariables();
+            List<Mutable<ILogicalExpression>> exprs = assignOp.getExpressions();            
+            for (int i = 0; i < vars.size(); i++) {
+                ILogicalExpression expr = exprs.get(i).getValue();
+                // Ignore functions that are in the doNotInline set.                
+                if (expr.getExpressionTag() == LogicalExpressionTag.FUNCTION_CALL) {
+                    AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
+                    if (doNotInlineFuncs.contains(funcExpr.getFunctionIdentifier())) {
+                        continue;
                     }
                 }
-                ecChange = true;
-            } else if (((AbstractLogicalExpression) rhs).getExpressionTag() == LogicalExpressionTag.CONSTANT) {
-                LogicalVariable varLeft = a.getVariables().get(0);
-                List<LogicalVariable> m = new LinkedList<LogicalVariable>();
-                m.add(varLeft);
-                EquivalenceClass ec = new EquivalenceClass(m, (ConstantExpression) rhs);
-                // equivClassesForParent.add(ec);
-                equivClasses.add(ec);
-                ecChange = true;
-            }
-        } else if (op.getOperatorTag() == LogicalOperatorTag.GROUP && !(context.checkIfInDontApplySet(this, op))) {
-            GroupByOperator group = (GroupByOperator) op;
-            Pair<Boolean, Boolean> r1 = processVarExprPairs(group.getGroupByList(), equivClasses);
-            Pair<Boolean, Boolean> r2 = processVarExprPairs(group.getDecorList(), equivClasses);
-            modified = modified || r1.first || r2.first;
-            ecChange = r1.second || r2.second;
-        }
-        if (op.getOperatorTag() == LogicalOperatorTag.PROJECT) {
-            assignVarsNeededByProject((ProjectOperator) op, equivClasses, context);
-        } else {
-            if (op.getOperatorTag() == LogicalOperatorTag.WRITE) {
-                substVisitorForWrites.setEquivalenceClasses(equivClasses);
-                if (op.acceptExpressionTransform(substVisitorForWrites)) {
-                    modified = true;
-                }
-            } else {
-                substVisitor.setEquivalenceClasses(equivClasses);
-                if (op.acceptExpressionTransform(substVisitor)) {
-                    modified = true;
-                    if (op.getOperatorTag() == LogicalOperatorTag.GROUP) {
-                        GroupByOperator group = (GroupByOperator) op;
-                        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> gp : group.getGroupByList()) {
-                            if (gp.first != null
-                                    && gp.second.getValue().getExpressionTag() == LogicalExpressionTag.VARIABLE) {
-                                LogicalVariable gv = ((VariableReferenceExpression) gp.second.getValue())
-                                        .getVariableReference();
-                                Iterator<Pair<LogicalVariable, Mutable<ILogicalExpression>>> iter = group
-                                        .getDecorList().iterator();
-                                while (iter.hasNext()) {
-                                    Pair<LogicalVariable, Mutable<ILogicalExpression>> dp = iter.next();
-                                    if (dp.first == null
-                                            && dp.second.getValue().getExpressionTag() == LogicalExpressionTag.VARIABLE) {
-                                        LogicalVariable dv = ((VariableReferenceExpression) dp.second.getValue())
-                                                .getVariableReference();
-                                        if (dv == gv) {
-                                            // The decor variable is redundant,
-                                            // since it is
-                                            // propagated as a grouping
-                                            // variable.
-                                            EquivalenceClass ec1 = findEquivClass(gv, equivClasses);
-                                            if (ec1 != null) {
-                                                ec1.addMember(gp.first);
-                                                ec1.setVariableRepresentative(gp.first);
-                                            } else {
-                                                List<LogicalVariable> varList = new ArrayList<LogicalVariable>();
-                                                varList.add(gp.first);
-                                                varList.add(gv);
-                                                ec1 = new EquivalenceClass(varList, gp.first);
-                                            }
-                                            iter.remove();
-                                            break;
-                                        }
-                                    }
-                                }
-                            }
-                        }
-                    }
-                }
+                varAssignRhs.put(vars.get(i), exprs.get(i).getValue());
             }
         }
-        return new Pair<Boolean, Boolean>(modified, ecChange);
-    }
 
-    private Pair<Boolean, Boolean> processVarExprPairs(
-            List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> vePairs, List<EquivalenceClass> equivClasses) {
-        boolean ecFromGroup = false;
+        // Descend into children removing projects on the way.
         boolean modified = false;
-        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> p : vePairs) {
-            ILogicalExpression expr = p.second.getValue();
-            if (p.first != null && expr.getExpressionTag() == LogicalExpressionTag.VARIABLE) {
-                VariableReferenceExpression varRef = (VariableReferenceExpression) expr;
-                LogicalVariable rhsVar = varRef.getVariableReference();
-                ecFromGroup = true;
-                EquivalenceClass ecRight = findEquivClass(rhsVar, equivClasses);
-                if (ecRight != null) {
-                    LogicalVariable replacingVar = ecRight.getVariableRepresentative();
-                    if (replacingVar != null && replacingVar != rhsVar) {
-                        varRef.setVariable(replacingVar);
-                        modified = true;
-                    }
-                }
-            }
+        for (Mutable<ILogicalOperator> inputOpRef : op.getInputs()) {
+            if (inlineVariables(inputOpRef, context)) {
+                modified = true;
+            }            
         }
-        return new Pair<Boolean, Boolean>(modified, ecFromGroup);
+
+        if (performBottomUpAction(op)) {
+            modified = true;
+        }
+        
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(op);
+            context.addToDontApplySet(this, op);
+            // Re-enable rules that we may have already tried. They could be applicable now after inlining.
+            context.removeFromAlreadyCompared(opRef.getValue());
+        }
+
+        return modified;
     }
 
-    // Instead of doing this, we could make Projection to be more expressive and
-    // also take constants (or even expression), at the expense of a more
-    // complex project push down.
-    private void assignVarsNeededByProject(ProjectOperator op, List<EquivalenceClass> equivClasses,
-            IOptimizationContext context) throws AlgebricksException {
-        List<LogicalVariable> prVars = op.getVariables();
-        int sz = prVars.size();
-        for (int i = 0; i < sz; i++) {
-            EquivalenceClass ec = findEquivClass(prVars.get(i), equivClasses);
-            if (ec != null) {
-                if (!ec.representativeIsConst()) {
-                    prVars.set(i, ec.getVariableRepresentative());
-                }
-            }
-        }
-    }
-
-    private final static EquivalenceClass findEquivClass(LogicalVariable var, List<EquivalenceClass> equivClasses) {
-        for (EquivalenceClass ec : equivClasses) {
-            if (ec.contains(var)) {
-                return ec;
-            }
-        }
-        return null;
-    }
-
-    private class VariableSubstitutionVisitor implements ILogicalExpressionReferenceTransform {
-        private List<EquivalenceClass> equivClasses;
+    protected class InlineVariablesVisitor implements ILogicalExpressionReferenceTransform {
+        
+        private final Map<LogicalVariable, ILogicalExpression> varAssignRhs;
+        private final Set<LogicalVariable> liveVars = new HashSet<LogicalVariable>();
+        private final List<LogicalVariable> rhsUsedVars = new ArrayList<LogicalVariable>();        
+        private ILogicalOperator op;
         private IOptimizationContext context;
-        private final boolean doNotSubstWithConst;
-
-        public VariableSubstitutionVisitor(boolean doNotSubstWithConst) {
-            this.doNotSubstWithConst = doNotSubstWithConst;
+        // If set, only replace this variable reference.
+        private LogicalVariable targetVar;
+        
+        public InlineVariablesVisitor(Map<LogicalVariable, ILogicalExpression> varAssignRhs) {
+            this.varAssignRhs = varAssignRhs;
         }
-
+        
+        public void setTargetVariable(LogicalVariable targetVar) {
+            this.targetVar = targetVar;
+        }
+        
         public void setContext(IOptimizationContext context) {
             this.context = context;
         }
 
-        public void setEquivalenceClasses(List<EquivalenceClass> equivClasses) {
-            this.equivClasses = equivClasses;
+        public void setOperator(ILogicalOperator op) throws AlgebricksException {
+            this.op = op;
+            liveVars.clear();
         }
-
+        
         @Override
-        public boolean transform(Mutable<ILogicalExpression> exprRef) {
+        public boolean transform(Mutable<ILogicalExpression> exprRef) throws AlgebricksException {            
             ILogicalExpression e = exprRef.getValue();
             switch (((AbstractLogicalExpression) e).getExpressionTag()) {
                 case VARIABLE: {
-                    // look for a required substitution
                     LogicalVariable var = ((VariableReferenceExpression) e).getVariableReference();
+                    // Restrict replacement to targetVar if it has been set.
+                    if (targetVar != null && var != targetVar) {
+                        return false;
+                    }
+                    // Make sure has not been excluded from inlining.
                     if (context.shouldNotBeInlined(var)) {
                         return false;
                     }
-                    EquivalenceClass ec = findEquivClass(var, equivClasses);
-                    if (ec == null) {
+                    ILogicalExpression rhs = varAssignRhs.get(var);
+                    if (rhs == null) {
+                        // Variable was not produced by an assign.
                         return false;
                     }
-                    if (ec.representativeIsConst()) {
-                        if (doNotSubstWithConst) {
-                            return false;
-                        }
-                        exprRef.setValue(ec.getConstRepresentative());
-                        return true;
-                    } else {
-                        LogicalVariable r = ec.getVariableRepresentative();
-                        if (!r.equals(var)) {
-                            exprRef.setValue(new VariableReferenceExpression(r));
-                            return true;
-                        } else {
+                    
+                    // Make sure used variables from rhs are live.
+                    if (liveVars.isEmpty()) {
+                        VariableUtilities.getLiveVariables(op, liveVars);
+                    }
+                    rhsUsedVars.clear();
+                    rhs.getUsedVariables(rhsUsedVars);
+                    for (LogicalVariable rhsUsedVar : rhsUsedVars) {
+                        if (!liveVars.contains(rhsUsedVar)) {
                             return false;
                         }
                     }
+                    
+                    // Replace variable reference with a clone of the rhs expr.
+                    exprRef.setValue(rhs.cloneExpression());
+                    return true;
                 }
                 case FUNCTION_CALL: {
                     AbstractFunctionCallExpression fce = (AbstractFunctionCallExpression) e;
-                    boolean m = false;
+                    boolean modified = false;
                     for (Mutable<ILogicalExpression> arg : fce.getArguments()) {
                         if (transform(arg)) {
-                            m = true;
+                            modified = true;
                         }
                     }
-                    return m;
+                    return modified;
                 }
                 default: {
                     return false;
                 }
             }
         }
-
     }
 }
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InsertProjectBeforeUnionRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InsertProjectBeforeUnionRule.java
index d54833e..431fca1 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InsertProjectBeforeUnionRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/InsertProjectBeforeUnionRule.java
@@ -87,6 +87,7 @@
         projectOp.getInputs().add(new MutableObject<ILogicalOperator>(parentOp));
         opUnion.getInputs().get(branch).setValue(projectOp);
         projectOp.setPhysicalOperator(new StreamProjectPOperator());
+        context.computeAndSetTypeEnvironmentForOperator(projectOp);
         context.computeAndSetTypeEnvironmentForOperator(parentOp);
     }
 
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceGroupByCombinerRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceGroupByCombinerRule.java
index 5c5fdb1..a8864fe 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceGroupByCombinerRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceGroupByCombinerRule.java
@@ -38,7 +38,6 @@
         if (context.checkIfInDontApplySet(this, op)) {
             return false;
         }
-        context.addToDontApplySet(this, op);
         if (op.getOperatorTag() != LogicalOperatorTag.GROUP) {
             return false;
         }
@@ -86,6 +85,7 @@
         opRef3.setValue(newGbyOp);
         typeGby(newGbyOp, context);
         typeGby(gbyOp, context);
+    	context.addToDontApplySet(this, op);
         return true;
     }
 
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceProjectsRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceProjectsRule.java
new file mode 100644
index 0000000..a057f4f
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/IntroduceProjectsRule.java
@@ -0,0 +1,171 @@
+/*
+ * Copyright 2009-2012 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.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+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.Triple;
+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.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.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Projects away unused variables at the earliest possible point.
+ * Does a full DFS sweep of the plan adding ProjectOperators in the bottom-up pass.
+ * Also, removes projects that have become useless.
+ * TODO: This rule 'recklessly' adds as many projects as possible, but there is no guarantee
+ * that the overall cost of the plan is reduced since project operators also add a cost.
+ */
+public class IntroduceProjectsRule implements IAlgebraicRewriteRule {
+
+    private final Set<LogicalVariable> usedVars = new HashSet<LogicalVariable>();
+    private final Set<LogicalVariable> liveVars = new HashSet<LogicalVariable>();
+    private final Set<LogicalVariable> producedVars = new HashSet<LogicalVariable>();
+    private final List<LogicalVariable> projectVars = new ArrayList<LogicalVariable>();
+    protected boolean hasRun = false;
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        if (hasRun) {
+            return false;
+        }
+        hasRun = true;
+        return introduceProjects(null, -1, opRef, Collections.<LogicalVariable> emptySet(), context);
+    }
+
+    protected boolean introduceProjects(AbstractLogicalOperator parentOp, int parentInputIndex,
+            Mutable<ILogicalOperator> opRef, Set<LogicalVariable> parentUsedVars, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        boolean modified = false;
+
+        usedVars.clear();
+        VariableUtilities.getUsedVariables(op, usedVars);
+
+        // In the top-down pass, maintain a set of variables that are used in op and all its parents.
+        HashSet<LogicalVariable> parentsUsedVars = new HashSet<LogicalVariable>();
+        parentsUsedVars.addAll(parentUsedVars);
+        parentsUsedVars.addAll(usedVars);
+
+        // Descend into children.        
+        for (int i = 0; i < op.getInputs().size(); i++) {
+            Mutable<ILogicalOperator> inputOpRef = op.getInputs().get(i);
+            if (introduceProjects(op, i, inputOpRef, parentsUsedVars, context)) {
+                modified = true;
+            }
+        }
+
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(op);
+        }
+        // In the bottom-up pass, determine which live variables are not used by op's parents.
+        // Such variables are be projected away.
+        liveVars.clear();
+        VariableUtilities.getLiveVariables(op, liveVars);
+        producedVars.clear();
+        VariableUtilities.getProducedVariables(op, producedVars);
+        liveVars.removeAll(producedVars);
+
+        projectVars.clear();
+        for (LogicalVariable liveVar : liveVars) {
+            if (parentsUsedVars.contains(liveVar)) {
+                projectVars.add(liveVar);
+            }
+        }
+
+        // Some of the variables that are live at this op are not used above.
+        if (projectVars.size() != liveVars.size()) {
+            // Add a project operator under each of op's qualifying input branches.
+            for (int i = 0; i < op.getInputs().size(); i++) {
+                ILogicalOperator childOp = op.getInputs().get(i).getValue();
+                liveVars.clear();
+                VariableUtilities.getLiveVariables(childOp, liveVars);
+                List<LogicalVariable> vars = new ArrayList<LogicalVariable>();
+                vars.addAll(projectVars);
+                // Only retain those variables that are live in the i-th input branch.
+                vars.retainAll(liveVars);
+                if (vars.size() != liveVars.size()) {
+                    ProjectOperator projectOp = new ProjectOperator(vars);
+                    projectOp.getInputs().add(new MutableObject<ILogicalOperator>(childOp));
+                    op.getInputs().get(i).setValue(projectOp);
+                    context.computeAndSetTypeEnvironmentForOperator(projectOp);
+                    modified = true;
+                }
+            }
+        } else if (op.getOperatorTag() == LogicalOperatorTag.PROJECT) {
+            // Check if the existing project has become useless.
+            liveVars.clear();
+            VariableUtilities.getLiveVariables(op.getInputs().get(0).getValue(), liveVars);
+            ProjectOperator projectOp = (ProjectOperator) op;
+            List<LogicalVariable> projectVars = projectOp.getVariables();
+            if (liveVars.size() == projectVars.size() && liveVars.containsAll(projectVars)) {
+                boolean eliminateProject = true;
+                // For UnionAll the variables must also be in exactly the correct order.
+                if (parentOp.getOperatorTag() == LogicalOperatorTag.UNIONALL) {
+                    eliminateProject = canEliminateProjectBelowUnion((UnionAllOperator) parentOp, projectOp,
+                            parentInputIndex);
+                }
+                if (eliminateProject) {
+                    // The existing project has become useless. Remove it.
+                    parentOp.getInputs().get(parentInputIndex).setValue(op.getInputs().get(0).getValue());
+                }
+            }
+        }
+
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(op);
+        }
+        return modified;
+    }
+    
+    private boolean canEliminateProjectBelowUnion(UnionAllOperator unionOp, ProjectOperator projectOp,
+            int unionInputIndex) throws AlgebricksException {
+        List<LogicalVariable> orderedLiveVars = new ArrayList<LogicalVariable>();
+        VariableUtilities.getLiveVariables(projectOp.getInputs().get(0).getValue(), orderedLiveVars);
+        int numVars = orderedLiveVars.size();
+        for (int i = 0; i < numVars; i++) {
+            Triple<LogicalVariable, LogicalVariable, LogicalVariable> varTriple = unionOp.getVariableMappings().get(i);
+            if (unionInputIndex == 0) {
+                if (varTriple.first != orderedLiveVars.get(i)) {
+                    return false;
+                }
+            } else {
+                if (varTriple.second != orderedLiveVars.get(i)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PullSelectOutOfEqJoin.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PullSelectOutOfEqJoin.java
index 75862cf..8b4f0a1 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PullSelectOutOfEqJoin.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PullSelectOutOfEqJoin.java
@@ -38,9 +38,6 @@
 
 public class PullSelectOutOfEqJoin implements IAlgebraicRewriteRule {
 
-    private List<Mutable<ILogicalExpression>> eqVarVarComps = new ArrayList<Mutable<ILogicalExpression>>();
-    private List<Mutable<ILogicalExpression>> otherPredicates = new ArrayList<Mutable<ILogicalExpression>>();
-
     @Override
     public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
         return false;
@@ -66,8 +63,8 @@
         if (!fi.equals(AlgebricksBuiltinFunctions.AND)) {
             return false;
         }
-        eqVarVarComps.clear();
-        otherPredicates.clear();
+        List<Mutable<ILogicalExpression>> eqVarVarComps = new ArrayList<Mutable<ILogicalExpression>>();
+        List<Mutable<ILogicalExpression>> otherPredicates = new ArrayList<Mutable<ILogicalExpression>>();
         for (Mutable<ILogicalExpression> arg : fexp.getArguments()) {
             if (isEqVarVar(arg.getValue())) {
                 eqVarVarComps.add(arg);
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushAssignBelowUnionAllRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushAssignBelowUnionAllRule.java
new file mode 100644
index 0000000..1bcf95a
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushAssignBelowUnionAllRule.java
@@ -0,0 +1,149 @@
+package edu.uci.ics.hyracks.algebricks.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+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.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.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.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Pushes an AssignOperator below a UnionAll operator by creating an new AssignOperator below each of 
+ * the UnionAllOperator's branches with appropriate variable replacements.
+ * This rule can help to enable other rules that are difficult to fire across a UnionAllOperator, 
+ * for example, eliminating common sub-expressions.
+ * 
+ * Example:
+ * 
+ * Before plan:
+ * ...
+ * assign [$$20, $$21] <- [funcA($$3), funcB($$6)]
+ *   union ($$1, $$2, $$3) ($$4, $$5, $$6)
+ *     union_branch_0
+ *       ...
+ *     union_branch_1
+ *       ...
+ *     
+ * After plan:
+ * ...
+ * union ($$1, $$2, $$3) ($$4, $$5, $$6) ($$22, $$24, $$20) ($$23, $$25, $$21)
+ *   assign [$$22, $$23] <- [funcA($$1), funcB($$4)]
+ *     union_branch_0
+ *       ...
+ *   assign [$$24, $$25] <- [funcA($$2), funcB($$5)]
+ *     union_branch_1
+ *       ...
+ */
+public class PushAssignBelowUnionAllRule implements IAlgebraicRewriteRule {
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        if (!op.hasInputs()) {
+            return false;
+        }
+
+        boolean modified = false;
+        for (int i = 0; i < op.getInputs().size(); i++) {
+            AbstractLogicalOperator childOp = (AbstractLogicalOperator) op.getInputs().get(i).getValue();
+            if (childOp.getOperatorTag() != LogicalOperatorTag.ASSIGN) {
+                continue;
+            }
+            AssignOperator assignOp = (AssignOperator) childOp;
+
+            AbstractLogicalOperator childOfChildOp = (AbstractLogicalOperator) assignOp.getInputs().get(0).getValue();
+            if (childOfChildOp.getOperatorTag() != LogicalOperatorTag.UNIONALL) {
+                continue;
+            }
+            UnionAllOperator unionOp = (UnionAllOperator) childOfChildOp;
+
+            Set<LogicalVariable> assignUsedVars = new HashSet<LogicalVariable>();
+            VariableUtilities.getUsedVariables(assignOp, assignUsedVars);
+
+            List<LogicalVariable> assignVars = assignOp.getVariables();
+
+            AssignOperator[] newAssignOps = new AssignOperator[2];
+            for (int j = 0; j < unionOp.getInputs().size(); j++) {
+                newAssignOps[j] = createAssignBelowUnionAllBranch(unionOp, j, assignOp, assignUsedVars, context);
+            }
+            // Add original assign variables to the union variable mappings.
+            for (int j = 0; j < assignVars.size(); j++) {
+                LogicalVariable first = newAssignOps[0].getVariables().get(j);
+                LogicalVariable second = newAssignOps[1].getVariables().get(j);
+                Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping = new Triple<LogicalVariable, LogicalVariable, LogicalVariable>(
+                        first, second, assignVars.get(j));
+                unionOp.getVariableMappings().add(varMapping);
+            }
+            context.computeAndSetTypeEnvironmentForOperator(unionOp);
+
+            // Remove original assign operator.
+            op.getInputs().set(i, assignOp.getInputs().get(0));
+            context.computeAndSetTypeEnvironmentForOperator(op);
+            modified = true;
+        }
+
+        return modified;
+    }
+
+    private AssignOperator createAssignBelowUnionAllBranch(UnionAllOperator unionOp, int inputIndex,
+            AssignOperator originalAssignOp, Set<LogicalVariable> assignUsedVars, IOptimizationContext context)
+            throws AlgebricksException {
+        AssignOperator newAssignOp = cloneAssignOperator(originalAssignOp, context);
+        newAssignOp.getInputs()
+                .add(new MutableObject<ILogicalOperator>(unionOp.getInputs().get(inputIndex).getValue()));
+        context.computeAndSetTypeEnvironmentForOperator(newAssignOp);
+        unionOp.getInputs().get(inputIndex).setValue(newAssignOp);
+        int numVarMappings = unionOp.getVariableMappings().size();
+        for (int i = 0; i < numVarMappings; i++) {
+            Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping = unionOp.getVariableMappings().get(i);
+            if (assignUsedVars.contains(varMapping.third)) {
+                LogicalVariable replacementVar;
+                if (inputIndex == 0) {
+                    replacementVar = varMapping.first;
+                } else {
+                    replacementVar = varMapping.second;
+                }
+                VariableUtilities.substituteVariables(newAssignOp, varMapping.third, replacementVar, context);
+            }
+        }
+        return newAssignOp;
+    }
+
+    /**
+     * Clones the given assign operator changing the returned variables to be new ones.
+     * Also, leaves the inputs of the clone clear.
+     */
+    private AssignOperator cloneAssignOperator(AssignOperator assignOp, IOptimizationContext context) {
+        List<LogicalVariable> vars = new ArrayList<LogicalVariable>();
+        List<Mutable<ILogicalExpression>> exprs = new ArrayList<Mutable<ILogicalExpression>>();
+        int numVars = assignOp.getVariables().size();
+        for (int i = 0; i < numVars; i++) {
+            vars.add(context.newVar());
+            exprs.add(new MutableObject<ILogicalExpression>(assignOp.getExpressions().get(i).getValue()
+                    .cloneExpression()));
+        }
+        AssignOperator assignCloneOp = new AssignOperator(vars, exprs);
+        assignCloneOp.setExecutionMode(assignOp.getExecutionMode());
+        return assignCloneOp;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushFunctionsBelowJoin.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushFunctionsBelowJoin.java
new file mode 100644
index 0000000..16b010e
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushFunctionsBelowJoin.java
@@ -0,0 +1,208 @@
+/*
+ * Copyright 2009-2012 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.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Set;
+
+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.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.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.AbstractLogicalExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractBinaryJoinOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Pushes function-call expressions below a join if possible.
+ * Assigns the result of such function-calls expressions to new variables, and replaces the original
+ * expression with a corresponding variable reference expression.
+ * This rule can help reduce the cost of computing expensive functions by pushing them below
+ * a join (which may blow up the cardinality).
+ * Also, this rule may help to enable other rules such as common subexpression elimination, again to reduce
+ * the number of calls to expensive functions.
+ * 
+ * Example: (we are pushing pushMeFunc)
+ * 
+ * Before plan:
+ * assign [$$10] <- [funcA(funcB(pushMeFunc($$3, $$4)))]
+ *   join (some condition) 
+ *     join_branch_0 where $$3 and $$4 are not live
+ *       ...
+ *     join_branch_1 where $$3 and $$4 are live
+ *       ...
+ * 
+ * After plan:
+ * assign [$$10] <- [funcA(funcB($$11))]
+ *   join (some condition) 
+ *     join_branch_0 where $$3 and $$4 are not live
+ *       ...
+ *     join_branch_1 where $$3 and $$4 are live
+ *       assign[$$11] <- [pushMeFunc($$3, $$4)]
+ *         ...
+ */
+public class PushFunctionsBelowJoin implements IAlgebraicRewriteRule {
+
+    private final Set<FunctionIdentifier> toPushFuncIdents;
+    private final List<Mutable<ILogicalExpression>> funcExprs = new ArrayList<Mutable<ILogicalExpression>>();
+    private final List<LogicalVariable> usedVars = new ArrayList<LogicalVariable>();
+    private final List<LogicalVariable> liveVars = new ArrayList<LogicalVariable>();
+
+    public PushFunctionsBelowJoin(Set<FunctionIdentifier> toPushFuncIdents) {
+        this.toPushFuncIdents = toPushFuncIdents;
+    }
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        if (op.getOperatorTag() != LogicalOperatorTag.ASSIGN) {
+            return false;
+        }
+        AssignOperator assignOp = (AssignOperator) op;
+
+        // Find a join operator below this assign.
+        Mutable<ILogicalOperator> joinOpRef = findJoinOp(assignOp.getInputs().get(0));
+        if (joinOpRef == null) {
+            return false;
+        }
+        AbstractBinaryJoinOperator joinOp = (AbstractBinaryJoinOperator) joinOpRef.getValue();
+
+        // Check if the assign uses a function that we wish to push below the join if possible.
+        funcExprs.clear();
+        gatherFunctionCalls(assignOp, funcExprs);
+        if (funcExprs.isEmpty()) {
+            return false;
+        }
+
+        // Try to push the functions down the input branches of the join.
+        boolean modified = false;
+        if (pushDownFunctions(joinOp, 0, funcExprs, context)) {
+            modified = true;
+        }
+        if (pushDownFunctions(joinOp, 1, funcExprs, context)) {
+            modified = true;
+        }
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(joinOp);
+        }
+        return modified;
+    }
+
+    private Mutable<ILogicalOperator> findJoinOp(Mutable<ILogicalOperator> opRef) {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        switch (op.getOperatorTag()) {
+            case INNERJOIN:
+            case LEFTOUTERJOIN: {
+                return opRef;
+            }
+            // Bail on these operators.
+            case GROUP:
+            case AGGREGATE:
+            case DISTINCT:
+            case UNNEST_MAP: {
+                return null;
+            }
+            // Traverse children.
+            default: {
+                for (Mutable<ILogicalOperator> childOpRef : op.getInputs()) {
+                    return findJoinOp(childOpRef);
+                }
+            }
+        }
+        return null;
+    }
+
+    private void gatherFunctionCalls(AssignOperator assignOp, List<Mutable<ILogicalExpression>> funcExprs) {
+        for (Mutable<ILogicalExpression> exprRef : assignOp.getExpressions()) {
+            gatherFunctionCalls(exprRef, funcExprs);
+        }
+    }
+
+    private void gatherFunctionCalls(Mutable<ILogicalExpression> exprRef, List<Mutable<ILogicalExpression>> funcExprs) {
+        AbstractLogicalExpression expr = (AbstractLogicalExpression) exprRef.getValue();
+        if (expr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+            return;
+        }
+        // Check whether the function is a function we want to push.
+        AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) expr;
+        if (toPushFuncIdents.contains(funcExpr.getFunctionIdentifier())) {
+            funcExprs.add(exprRef);
+        }
+        // Traverse arguments.
+        for (Mutable<ILogicalExpression> funcArg : funcExpr.getArguments()) {
+            gatherFunctionCalls(funcArg, funcExprs);
+        }
+    }
+
+    private boolean pushDownFunctions(AbstractBinaryJoinOperator joinOp, int inputIndex,
+            List<Mutable<ILogicalExpression>> funcExprs, IOptimizationContext context) throws AlgebricksException {
+        ILogicalOperator joinInputOp = joinOp.getInputs().get(inputIndex).getValue();
+        liveVars.clear();
+        VariableUtilities.getLiveVariables(joinInputOp, liveVars);
+        Iterator<Mutable<ILogicalExpression>> funcIter = funcExprs.iterator();
+        List<LogicalVariable> assignVars = null;
+        List<Mutable<ILogicalExpression>> assignExprs = null;
+        while (funcIter.hasNext()) {
+            Mutable<ILogicalExpression> funcExprRef = funcIter.next();
+            ILogicalExpression funcExpr = funcExprRef.getValue();
+            usedVars.clear();
+            funcExpr.getUsedVariables(usedVars);
+            // Check if we can push the function down this branch.
+            if (liveVars.containsAll(usedVars)) {
+                if (assignVars == null) {
+                    assignVars = new ArrayList<LogicalVariable>();
+                    assignExprs = new ArrayList<Mutable<ILogicalExpression>>();
+                }
+                // Replace the original expression with a variable reference expression.
+                LogicalVariable replacementVar = context.newVar();
+                assignVars.add(replacementVar);
+                assignExprs.add(new MutableObject<ILogicalExpression>(funcExpr));
+                funcExprRef.setValue(new VariableReferenceExpression(replacementVar));
+                funcIter.remove();
+            }
+        }
+        // Create new assign operator below the join if any functions can be pushed.
+        if (assignVars != null) {
+            AssignOperator newAssign = new AssignOperator(assignVars, assignExprs);
+            newAssign.getInputs().add(new MutableObject<ILogicalOperator>(joinInputOp));
+            newAssign.setExecutionMode(joinOp.getExecutionMode());
+            joinOp.getInputs().get(inputIndex).setValue(newAssign);
+            context.computeAndSetTypeEnvironmentForOperator(newAssign);
+            return true;
+        }
+        return false;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushSelectIntoJoinRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushSelectIntoJoinRule.java
index 8c679c5..99a6b8c 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushSelectIntoJoinRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/PushSelectIntoJoinRule.java
@@ -143,11 +143,11 @@
         if (!intersectsBranch[0] && !intersectsBranch[1]) {
             return false;
         }
+        if (needToPushOps) {
+            pushOps(pushedOnLeft, joinBranchLeftRef, context);
+            pushOps(pushedOnRight, joinBranchRightRef, context);
+        }
         if (intersectsAllBranches) {
-            if (needToPushOps) {
-                pushOps(pushedOnLeft, joinBranchLeftRef, context);
-                pushOps(pushedOnRight, joinBranchRightRef, context);
-            }
             addCondToJoin(select, join, context);
         } else { // push down
             Iterator<Mutable<ILogicalOperator>> branchIter = join.getInputs().iterator();
@@ -156,13 +156,6 @@
                 Mutable<ILogicalOperator> branch = branchIter.next();
                 boolean inter = intersectsBranch[j];
                 if (inter) {
-                    if (needToPushOps) {
-                        if (j == 0) {
-                            pushOps(pushedOnLeft, joinBranchLeftRef, context);
-                        } else {
-                            pushOps(pushedOnRight, joinBranchRightRef, context);
-                        }
-                    }
                     copySelectToBranch(select, branch, context);
                 }
 
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantGroupByDecorVars.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantGroupByDecorVars.java
new file mode 100644
index 0000000..1106898
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantGroupByDecorVars.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.rewriter.rules;
+
+import java.util.HashSet;
+import java.util.Iterator;
+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.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.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.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Removes duplicate variables from a group-by operator's decor list.
+ */
+public class RemoveRedundantGroupByDecorVars implements IAlgebraicRewriteRule {
+
+    private final Set<LogicalVariable> vars = new HashSet<LogicalVariable>();
+    
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        if (op.getOperatorTag() != LogicalOperatorTag.GROUP) {
+            return false;
+        }
+        if (context.checkIfInDontApplySet(this, op)) {
+            return false;
+        }
+        vars.clear();
+        
+        boolean modified = false;
+        GroupByOperator groupOp = (GroupByOperator) op;
+        Iterator<Pair<LogicalVariable, Mutable<ILogicalExpression>>> iter = groupOp.getDecorList().iterator();
+        while (iter.hasNext()) {
+            Pair<LogicalVariable, Mutable<ILogicalExpression>> decor = iter.next();
+            if (decor.first != null || decor.second.getValue().getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                continue;
+            }
+            VariableReferenceExpression varRefExpr = (VariableReferenceExpression) decor.second.getValue();
+            LogicalVariable var = varRefExpr.getVariableReference();
+            if (vars.contains(var)) {
+                iter.remove();
+                modified = true;
+            } else {
+                vars.add(var);
+            }
+        }
+        if (modified) {
+            context.addToDontApplySet(this, op);
+        }
+        return modified;
+    }
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        return false;
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantVariablesRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantVariablesRule.java
new file mode 100644
index 0000000..ec57be5
--- /dev/null
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveRedundantVariablesRule.java
@@ -0,0 +1,291 @@
+/*
+ * 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.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.Iterator;
+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.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.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.AbstractLogicalExpression;
+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.AbstractOperatorWithNestedPlans;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.ProjectOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Replaces redundant variable references with their bottom-most equivalent representative.
+ * Does a DFS sweep over the plan keeping track of variable equivalence classes.
+ * For example, this rule would perform the following rewrite.
+ * 
+ * Before Plan:
+ * select (function-call: func, Args:[%0->$$11])
+ *   project [$11]
+ *     assign [$$11] <- [$$10]
+ *       assign [$$10] <- [$$9]
+ *         assign [$$9] <- ...
+ *           ...
+ *           
+ * After Plan:
+ * select (function-call: func, Args:[%0->$$9])
+ *   project [$9]
+ *     assign [$$11] <- [$$9]
+ *       assign [$$10] <- [$$9]
+ *         assign [$$9] <- ...
+ *           ...
+ */
+public class RemoveRedundantVariablesRule implements IAlgebraicRewriteRule {
+
+    private final VariableSubstitutionVisitor substVisitor = new VariableSubstitutionVisitor();
+    private final Map<LogicalVariable, List<LogicalVariable>> equivalentVarsMap = new HashMap<LogicalVariable, List<LogicalVariable>>();
+
+    protected boolean hasRun = false;
+    
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) throws AlgebricksException {
+        if (context.checkIfInDontApplySet(this, opRef.getValue())) {
+            return false;
+        }
+        equivalentVarsMap.clear();
+        boolean modified = removeRedundantVariables(opRef, context);
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(opRef.getValue());
+        }
+        return modified;
+    }
+
+    private void updateEquivalenceClassMap(LogicalVariable lhs, LogicalVariable rhs) {
+        List<LogicalVariable> equivalentVars = equivalentVarsMap.get(rhs);
+        if (equivalentVars == null) {
+            equivalentVars = new ArrayList<LogicalVariable>();
+            // The first element in the list is the bottom-most representative which will replace all equivalent vars.
+            equivalentVars.add(rhs);
+            equivalentVars.add(lhs);
+            equivalentVarsMap.put(rhs, equivalentVars);
+        }
+        equivalentVarsMap.put(lhs, equivalentVars);
+        equivalentVars.get(0);
+    }
+
+    private boolean removeRedundantVariables(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
+        boolean modified = false;
+
+        // Recurse into children.
+        for (Mutable<ILogicalOperator> inputOpRef : op.getInputs()) {
+            if (removeRedundantVariables(inputOpRef, context)) {
+                modified = true;
+            }
+        }
+
+        // Update equivalence class map.
+        if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
+            AssignOperator assignOp = (AssignOperator) op;
+            int numVars = assignOp.getVariables().size();
+            for (int i = 0; i < numVars; i++) {
+                ILogicalExpression expr = assignOp.getExpressions().get(i).getValue();
+                if (expr.getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                    continue;
+                }
+                VariableReferenceExpression rhsVarRefExpr = (VariableReferenceExpression) expr;
+                // Update equivalence class map.
+                LogicalVariable lhs = assignOp.getVariables().get(i);
+                LogicalVariable rhs = rhsVarRefExpr.getVariableReference();
+                updateEquivalenceClassMap(lhs, rhs);
+            }
+        }
+
+        // Replace variable references with their first representative. 
+        if (op.getOperatorTag() == LogicalOperatorTag.PROJECT) {
+            // The project operator does not use expressions, so we need to replace it's variables manually.
+            if (replaceProjectVars((ProjectOperator) op)) {
+                modified = true;
+            }
+        } else if(op.getOperatorTag() == LogicalOperatorTag.UNIONALL) {
+            // Replace redundant variables manually in the UnionAll operator.
+            if (replaceUnionAllVars((UnionAllOperator) op)) {
+                modified = true;
+            }
+        } else {
+            if (op.acceptExpressionTransform(substVisitor)) {
+                modified = true;
+            }
+        }
+
+        // Perform variable replacement in nested plans. 
+        if (op.hasNestedPlans()) {
+            AbstractOperatorWithNestedPlans opWithNestedPlan = (AbstractOperatorWithNestedPlans) op;
+            for (ILogicalPlan nestedPlan : opWithNestedPlan.getNestedPlans()) {
+                for (Mutable<ILogicalOperator> rootRef : nestedPlan.getRoots()) {
+                    if (removeRedundantVariables(rootRef, context)) {
+                        modified = true;
+                    }
+                }
+            }
+        }
+
+        // Deal with re-mapping of variables in group by.
+        if (op.getOperatorTag() == LogicalOperatorTag.GROUP) {
+            if (handleGroupByVarRemapping((GroupByOperator) op)) {
+                modified = true;
+            }
+        }
+
+        if (modified) {
+            context.computeAndSetTypeEnvironmentForOperator(op);
+            context.addToDontApplySet(this, op);
+        }
+        return modified;
+    }
+
+    private boolean handleGroupByVarRemapping(GroupByOperator groupOp) {
+        boolean modified = false;
+        for (Pair<LogicalVariable, Mutable<ILogicalExpression>> gp : groupOp.getGroupByList()) {
+            if (gp.first == null || gp.second.getValue().getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                continue;
+            }
+            LogicalVariable groupByVar = ((VariableReferenceExpression) gp.second.getValue()).getVariableReference();
+            Iterator<Pair<LogicalVariable, Mutable<ILogicalExpression>>> iter = groupOp.getDecorList().iterator();
+            while (iter.hasNext()) {
+                Pair<LogicalVariable, Mutable<ILogicalExpression>> dp = iter.next();
+                if (dp.first != null || dp.second.getValue().getExpressionTag() != LogicalExpressionTag.VARIABLE) {
+                    continue;
+                }
+                LogicalVariable dv = ((VariableReferenceExpression) dp.second.getValue()).getVariableReference();
+                if (dv == groupByVar) {
+                    // The decor variable is redundant, since it is propagated as a grouping variable.
+                    List<LogicalVariable> equivalentVars = equivalentVarsMap.get(groupByVar);
+                    if (equivalentVars != null) {
+                        // Change representative of this equivalence class.
+                        equivalentVars.set(0, gp.first);
+                        equivalentVarsMap.put(gp.first, equivalentVars);
+                    } else {
+                        updateEquivalenceClassMap(gp.first, groupByVar);
+                    }
+                    iter.remove();
+                    modified = true;
+                    break;
+                }
+            }
+        }
+        return modified;
+    }
+
+    /**
+     * Replace the projects's variables with their corresponding representative
+     * from the equivalence class map (if any).
+     * We cannot use the VariableSubstitutionVisitor here because the project ops
+     * maintain their variables as a list and not as expressions.
+     */
+    private boolean replaceProjectVars(ProjectOperator op) throws AlgebricksException {
+        List<LogicalVariable> vars = op.getVariables();
+        int size = vars.size();
+        boolean modified = false;
+        for (int i = 0; i < size; i++) {
+            LogicalVariable var = vars.get(i);
+            List<LogicalVariable> equivalentVars = equivalentVarsMap.get(var);
+            if (equivalentVars == null) {
+                continue;
+            }
+            // Replace with equivalence class representative.
+            LogicalVariable representative = equivalentVars.get(0);
+            if (representative != var) {
+                vars.set(i, equivalentVars.get(0));
+                modified = true;
+            }
+        }
+        return modified;
+    }
+
+    private boolean replaceUnionAllVars(UnionAllOperator op) throws AlgebricksException {
+        boolean modified = false;
+        for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping : op.getVariableMappings()) {
+            List<LogicalVariable> firstEquivalentVars = equivalentVarsMap.get(varMapping.first);
+            List<LogicalVariable> secondEquivalentVars = equivalentVarsMap.get(varMapping.second);
+            // Replace variables with their representative.
+            if (firstEquivalentVars != null) {
+                varMapping.first = firstEquivalentVars.get(0);
+                modified = true;
+            }
+            if (secondEquivalentVars != null) {
+                varMapping.second = secondEquivalentVars.get(0);
+                modified = true;
+            }
+        }
+        return modified;
+    }
+    
+    private class VariableSubstitutionVisitor implements ILogicalExpressionReferenceTransform {
+        @Override
+        public boolean transform(Mutable<ILogicalExpression> exprRef) {
+            ILogicalExpression e = exprRef.getValue();
+            switch (((AbstractLogicalExpression) e).getExpressionTag()) {
+                case VARIABLE: {
+                    // Replace variable references with their equivalent representative in the equivalence class map.
+                    VariableReferenceExpression varRefExpr = (VariableReferenceExpression) e;
+                    LogicalVariable var = varRefExpr.getVariableReference();
+                    List<LogicalVariable> equivalentVars = equivalentVarsMap.get(var);
+                    if (equivalentVars == null) {
+                        return false;
+                    }
+                    LogicalVariable representative = equivalentVars.get(0);
+                    if (representative != var) {
+                        varRefExpr.setVariable(representative);
+                        return true;
+                    }
+                    return false;
+                }
+                case FUNCTION_CALL: {
+                    AbstractFunctionCallExpression funcExpr = (AbstractFunctionCallExpression) e;
+                    boolean modified = false;
+                    for (Mutable<ILogicalExpression> arg : funcExpr.getArguments()) {
+                        if (transform(arg)) {
+                            modified = true;
+                        }
+                    }
+                    return modified;
+                }
+                default: {
+                    return false;
+                }
+            }
+        }
+    }
+}
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
index c53ea0a..e0c2741 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
@@ -23,6 +23,7 @@
 import org.apache.commons.lang3.mutable.Mutable;
 
 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.ILogicalExpression;
 import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.base.ILogicalPlan;
@@ -33,10 +34,14 @@
 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.UnionAllOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
 import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
 
+/**
+ * Removes unused variables from Assign, Unnest, Aggregate, and UnionAll operators.
+ */
 public class RemoveUnusedAssignAndAggregateRule implements IAlgebraicRewriteRule {
 
     @Override
@@ -55,7 +60,7 @@
         if (smthToRemove) {
             removeUnusedAssigns(opRef, toRemove, context);
         }
-        return smthToRemove;
+        return !toRemove.isEmpty();
     }
 
     private void removeUnusedAssigns(Mutable<ILogicalOperator> opRef, Set<LogicalVariable> toRemove,
@@ -87,28 +92,59 @@
 
     private int removeFromAssigns(AbstractLogicalOperator op, Set<LogicalVariable> toRemove,
             IOptimizationContext context) throws AlgebricksException {
-        if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
-            AssignOperator assign = (AssignOperator) op;
-            if (removeUnusedVarsAndExprs(toRemove, assign.getVariables(), assign.getExpressions())) {
-                context.computeAndSetTypeEnvironmentForOperator(assign);
+        switch (op.getOperatorTag()) {
+            case ASSIGN: {
+                AssignOperator assign = (AssignOperator) op;
+                if (removeUnusedVarsAndExprs(toRemove, assign.getVariables(), assign.getExpressions())) {
+                    context.computeAndSetTypeEnvironmentForOperator(assign);
+                }
+                return assign.getVariables().size();
             }
-            return assign.getVariables().size();
-        } else if (op.getOperatorTag() == LogicalOperatorTag.AGGREGATE) {
-            AggregateOperator agg = (AggregateOperator) op;
-            if (removeUnusedVarsAndExprs(toRemove, agg.getVariables(), agg.getExpressions())) {
-                context.computeAndSetTypeEnvironmentForOperator(agg);
+            case AGGREGATE: {
+                AggregateOperator agg = (AggregateOperator) op;
+                if (removeUnusedVarsAndExprs(toRemove, agg.getVariables(), agg.getExpressions())) {
+                    context.computeAndSetTypeEnvironmentForOperator(agg);
+                }
+                return agg.getVariables().size();
             }
-            return agg.getVariables().size();
-        } else if (op.getOperatorTag() == LogicalOperatorTag.UNNEST) {
-            UnnestOperator uOp = (UnnestOperator) op;
-            LogicalVariable pVar = uOp.getPositionalVariable();
-            if (pVar != null && toRemove.contains(pVar)) {
-                uOp.setPositionalVariable(null);
+            case UNNEST: {
+                UnnestOperator uOp = (UnnestOperator) op;
+                LogicalVariable pVar = uOp.getPositionalVariable();
+                if (pVar != null && toRemove.contains(pVar)) {
+                    uOp.setPositionalVariable(null);
+                }
+                break;
+            }
+            case UNIONALL: {
+                UnionAllOperator unionOp = (UnionAllOperator) op;
+                if (removeUnusedVarsFromUnionAll(unionOp, toRemove)) {
+                    context.computeAndSetTypeEnvironmentForOperator(unionOp);
+                }
+                return unionOp.getVariableMappings().size();
             }
         }
         return -1;
     }
 
+    private boolean removeUnusedVarsFromUnionAll(UnionAllOperator unionOp, Set<LogicalVariable> toRemove) {
+        Iterator<Triple<LogicalVariable, LogicalVariable, LogicalVariable>> iter = unionOp.getVariableMappings()
+                .iterator();
+        boolean modified = false;
+        Set<LogicalVariable> removeFromRemoveSet = new HashSet<LogicalVariable>();
+        while (iter.hasNext()) {
+            Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping = iter.next();
+            if (toRemove.contains(varMapping.third)) {
+                iter.remove();
+                modified = true;
+            }
+            // In any case, make sure we do not removing these variables.
+            removeFromRemoveSet.add(varMapping.first);
+            removeFromRemoveSet.add(varMapping.second);
+        }
+        toRemove.removeAll(removeFromRemoveSet);
+        return modified;
+    }
+
     private boolean removeUnusedVarsAndExprs(Set<LogicalVariable> toRemove, List<LogicalVariable> varList,
             List<Mutable<ILogicalExpression>> exprList) {
         boolean changed = false;
@@ -142,22 +178,41 @@
                 }
             }
         }
-        if (op.getOperatorTag() == LogicalOperatorTag.ASSIGN) {
-            AssignOperator assign = (AssignOperator) op;
-            toRemove.addAll(assign.getVariables());
-        } else if (op.getOperatorTag() == LogicalOperatorTag.AGGREGATE) {
-            AggregateOperator agg = (AggregateOperator) op;
-            toRemove.addAll(agg.getVariables());
-        } else if (op.getOperatorTag() == LogicalOperatorTag.UNNEST) {
-            UnnestOperator uOp = (UnnestOperator) op;
-            LogicalVariable pVar = uOp.getPositionalVariable();
-            if (pVar != null) {
-                toRemove.add(pVar);
+        boolean removeUsedVars = true;
+        switch (op.getOperatorTag()) {
+            case ASSIGN: {
+                AssignOperator assign = (AssignOperator) op;
+                toRemove.addAll(assign.getVariables());
+                break;
+            }
+            case AGGREGATE: {
+                AggregateOperator agg = (AggregateOperator) op;
+                toRemove.addAll(agg.getVariables());
+                break;
+            }
+            case UNNEST: {
+                UnnestOperator uOp = (UnnestOperator) op;
+                LogicalVariable pVar = uOp.getPositionalVariable();
+                if (pVar != null) {
+                    toRemove.add(pVar);
+                }
+                break;
+            }
+            case UNIONALL: {
+                UnionAllOperator unionOp = (UnionAllOperator) op;
+                for (Triple<LogicalVariable, LogicalVariable, LogicalVariable> varMapping : unionOp
+                        .getVariableMappings()) {
+                    toRemove.add(varMapping.third);
+                }
+                removeUsedVars = false;
+                break;
             }
         }
-        List<LogicalVariable> used = new LinkedList<LogicalVariable>();
-        VariableUtilities.getUsedVariables(op, used);
-        toRemove.removeAll(used);
+        if (removeUsedVars) {
+            List<LogicalVariable> used = new LinkedList<LogicalVariable>();
+            VariableUtilities.getUsedVariables(op, used);
+            toRemove.removeAll(used);
+        }
     }
 
 }
diff --git a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/SetAlgebricksPhysicalOperatorsRule.java b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/SetAlgebricksPhysicalOperatorsRule.java
index 38cf96e..60a4fbb 100644
--- a/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/SetAlgebricksPhysicalOperatorsRule.java
+++ b/fullstack/algebricks/algebricks-rewriter/src/main/java/edu/uci/ics/hyracks/algebricks/rewriter/rules/SetAlgebricksPhysicalOperatorsRule.java
@@ -38,6 +38,7 @@
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.AggregatePOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.AssignPOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.DataSourceScanPOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.DistributeResultPOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.EmptyTupleSourcePOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.ExternalGroupByPOperator;
 import edu.uci.ics.hyracks.algebricks.core.algebra.operators.physical.InMemoryStableSortPOperator;
@@ -245,6 +246,10 @@
                     op.setPhysicalOperator(new SinkWritePOperator());
                     break;
                 }
+                case DISTRIBUTE_RESULT: {
+                    op.setPhysicalOperator(new DistributeResultPOperator());
+                    break;
+                }
                 case WRITE_RESULT: {
                     WriteResultOperator opLoad = (WriteResultOperator) op;
                     LogicalVariable payload;
@@ -267,8 +272,8 @@
                     List<LogicalVariable> secondaryKeys = new ArrayList<LogicalVariable>();
                     getKeys(opInsDel.getPrimaryKeyExpressions(), primaryKeys);
                     getKeys(opInsDel.getSecondaryKeyExpressions(), secondaryKeys);
-                    op.setPhysicalOperator(new IndexInsertDeletePOperator(primaryKeys, secondaryKeys, 
-                    		opInsDel.getFilterExpression(), opInsDel.getDataSourceIndex()));
+                    op.setPhysicalOperator(new IndexInsertDeletePOperator(primaryKeys, secondaryKeys, opInsDel
+                            .getFilterExpression(), opInsDel.getDataSourceIndex()));
                     break;
                 }
                 case SINK: {
diff --git a/fullstack/algebricks/algebricks-runtime/pom.xml b/fullstack/algebricks/algebricks-runtime/pom.xml
index e40dfb0..e438283 100644
--- a/fullstack/algebricks/algebricks-runtime/pom.xml
+++ b/fullstack/algebricks/algebricks-runtime/pom.xml
@@ -16,8 +16,9 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
         </configuration>
       </plugin>
     </plugins>
diff --git a/fullstack/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/serializer/ResultSerializerFactoryProvider.java b/fullstack/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/serializer/ResultSerializerFactoryProvider.java
new file mode 100644
index 0000000..4f28c81
--- /dev/null
+++ b/fullstack/algebricks/algebricks-runtime/src/main/java/edu/uci/ics/hyracks/algebricks/runtime/serializer/ResultSerializerFactoryProvider.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.runtime.serializer;
+
+import java.io.PrintStream;
+import java.nio.BufferOverflowException;
+
+import edu.uci.ics.hyracks.algebricks.common.exceptions.AlgebricksException;
+import edu.uci.ics.hyracks.algebricks.data.IAWriter;
+import edu.uci.ics.hyracks.algebricks.data.IAWriterFactory;
+import edu.uci.ics.hyracks.algebricks.data.IPrinterFactory;
+import edu.uci.ics.hyracks.algebricks.data.IResultSerializerFactoryProvider;
+import edu.uci.ics.hyracks.api.comm.IFrameTupleAccessor;
+import edu.uci.ics.hyracks.api.dataflow.value.IResultSerializer;
+import edu.uci.ics.hyracks.api.dataflow.value.IResultSerializerFactory;
+import edu.uci.ics.hyracks.api.dataflow.value.RecordDescriptor;
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+
+public class ResultSerializerFactoryProvider implements IResultSerializerFactoryProvider {
+    private static final long serialVersionUID = 1L;
+
+    public static final ResultSerializerFactoryProvider INSTANCE = new ResultSerializerFactoryProvider();
+
+    private ResultSerializerFactoryProvider() {
+    }
+
+    @Override
+    public IResultSerializerFactory getAqlResultSerializerFactoryProvider(final int[] fields,
+            final IPrinterFactory[] printerFactories, final IAWriterFactory writerFactory) {
+        return new IResultSerializerFactory() {
+            private static final long serialVersionUID = 1L;
+
+            @Override
+            public IResultSerializer createResultSerializer(RecordDescriptor inputRecordDesc, PrintStream printStream) {
+                final IAWriter writer = writerFactory.createWriter(fields, printStream, printerFactories,
+                        inputRecordDesc);
+
+                return new IResultSerializer() {
+                    private static final long serialVersionUID = 1L;
+
+                    @Override
+                    public void init() throws HyracksDataException {
+                        try {
+                            writer.init();
+                        } catch (AlgebricksException e) {
+                            throw new HyracksDataException(e);
+                        }
+                    }
+
+                    @Override
+                    public boolean appendTuple(IFrameTupleAccessor tAccess, int tIdx) throws HyracksDataException {
+                        try {
+                            writer.printTuple(tAccess, tIdx);
+                        } catch (BufferOverflowException e) {
+                            return false;
+                        } catch (AlgebricksException e) {
+                            throw new HyracksDataException(e);
+                        }
+                        return true;
+                    }
+                };
+            }
+        };
+    }
+}
diff --git a/fullstack/algebricks/algebricks-tests/pom.xml b/fullstack/algebricks/algebricks-tests/pom.xml
index 19e6711..c114881 100644
--- a/fullstack/algebricks/algebricks-tests/pom.xml
+++ b/fullstack/algebricks/algebricks-tests/pom.xml
@@ -16,9 +16,11 @@
         <artifactId>maven-compiler-plugin</artifactId>
         <version>2.0.2</version>
         <configuration>
-          <source>1.6</source>
-          <target>1.6</target>
-        </configuration>
+          <source>1.7</source>
+          <target>1.7</target>
+          <fork>true</fork>
+	  <encoding>UTF-8</encoding>
+	</configuration>
       </plugin>
       <plugin>
         <artifactId>maven-antrun-plugin</artifactId>
diff --git a/fullstack/algebricks/algebricks-tests/src/test/java/edu/uci/ics/hyracks/algebricks/tests/util/AlgebricksHyracksIntegrationUtil.java b/fullstack/algebricks/algebricks-tests/src/test/java/edu/uci/ics/hyracks/algebricks/tests/util/AlgebricksHyracksIntegrationUtil.java
index b5c4b47..dad7cd0 100644
--- a/fullstack/algebricks/algebricks-tests/src/test/java/edu/uci/ics/hyracks/algebricks/tests/util/AlgebricksHyracksIntegrationUtil.java
+++ b/fullstack/algebricks/algebricks-tests/src/test/java/edu/uci/ics/hyracks/algebricks/tests/util/AlgebricksHyracksIntegrationUtil.java
@@ -3,9 +3,9 @@
  * 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.
@@ -55,6 +55,7 @@
         ncConfig1.ccPort = TEST_HYRACKS_CC_CLUSTER_NET_PORT;
         ncConfig1.clusterNetIPAddress = "127.0.0.1";
         ncConfig1.dataIPAddress = "127.0.0.1";
+        ncConfig1.datasetIPAddress = "127.0.0.1";
         ncConfig1.nodeId = NC1_ID;
         nc1 = new NodeControllerService(ncConfig1);
         nc1.start();
@@ -64,6 +65,7 @@
         ncConfig2.ccPort = TEST_HYRACKS_CC_CLUSTER_NET_PORT;
         ncConfig2.clusterNetIPAddress = "127.0.0.1";
         ncConfig2.dataIPAddress = "127.0.0.1";
+        ncConfig2.datasetIPAddress = "127.0.0.1";
         ncConfig2.nodeId = NC2_ID;
         nc2 = new NodeControllerService(ncConfig2);
         nc2.start();
@@ -85,4 +87,4 @@
         hcc.waitForCompletion(jobId);
     }
 
-}
\ No newline at end of file
+}