diff --git a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
index 1f3801c..e13da67 100644
--- a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
+++ b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
@@ -35,6 +35,7 @@
 import edu.uci.ics.asterix.optimizer.rules.IntroduceRapidFrameFlushProjectRule;
 import edu.uci.ics.asterix.optimizer.rules.IntroduceSecondaryIndexInsertDeleteRule;
 import edu.uci.ics.asterix.optimizer.rules.IntroduceStaticTypeCastForInsertRule;
+import edu.uci.ics.asterix.optimizer.rules.IntroduceUnnestForCollectionToSequenceRule;
 import edu.uci.ics.asterix.optimizer.rules.LoadRecordFieldsRule;
 import edu.uci.ics.asterix.optimizer.rules.NestGroupByRule;
 import edu.uci.ics.asterix.optimizer.rules.NestedSubplanToJoinRule;
@@ -110,6 +111,7 @@
 
     public final static List<IAlgebraicRewriteRule> buildNormalizationRuleCollection() {
         List<IAlgebraicRewriteRule> normalization = new LinkedList<IAlgebraicRewriteRule>();
+        normalization.add(new IntroduceUnnestForCollectionToSequenceRule());
         normalization.add(new EliminateSubplanRule());
         normalization.add(new EnforceOrderByAfterSubplan());
         normalization.add(new PushAggFuncIntoStandaloneAggregateRule());
diff --git a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/IntroduceUnnestForCollectionToSequenceRule.java b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/IntroduceUnnestForCollectionToSequenceRule.java
new file mode 100644
index 0000000..984f4dd
--- /dev/null
+++ b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/rules/IntroduceUnnestForCollectionToSequenceRule.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2009-2013 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.asterix.optimizer.rules;
+
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+
+import edu.uci.ics.asterix.aql.util.FunctionUtils;
+import edu.uci.ics.asterix.om.functions.AsterixBuiltinFunctions;
+import edu.uci.ics.asterix.om.types.IAType;
+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.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.UnnestingFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import edu.uci.ics.hyracks.algebricks.core.algebra.operators.logical.UnnestOperator;
+import edu.uci.ics.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * This rule introduces a unnest operator for the collection-to-sequence function (if the input to the function is a collection).
+ * 
+ * @author yingyib
+ */
+public class IntroduceUnnestForCollectionToSequenceRule 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.getOperatorTag() != LogicalOperatorTag.ASSIGN) {
+            return false;
+        }
+        AssignOperator assign = (AssignOperator) op;
+        List<Mutable<ILogicalExpression>> exprs = assign.getExpressions();
+        if (exprs.size() != 1) {
+            return false;
+        }
+        ILogicalExpression expr = exprs.get(0).getValue();
+        if (expr.getExpressionTag() != LogicalExpressionTag.FUNCTION_CALL) {
+            return false;
+        }
+        AbstractFunctionCallExpression func = (AbstractFunctionCallExpression) expr;
+        if (func.getFunctionIdentifier() != AsterixBuiltinFunctions.COLLECTION_TO_SEQUENCE) {
+            return false;
+        }
+
+        IVariableTypeEnvironment env = assign.computeInputTypeEnvironment(context);
+        ILogicalExpression argExpr = func.getArguments().get(0).getValue();
+        IAType outerExprType = (IAType) env.getType(expr);
+        IAType innerExprType = (IAType) env.getType(argExpr);
+        if (outerExprType.equals(innerExprType)) {
+            /** nothing is changed with the collection-to-sequence function, remove the collection-sequence function call */
+            assign.getExpressions().set(0, new MutableObject<ILogicalExpression>(argExpr));
+            return true;
+        }
+        /** change the assign operator to an unnest operator */
+        LogicalVariable var = assign.getVariables().get(0);
+        @SuppressWarnings("unchecked")
+        UnnestOperator unnest = new UnnestOperator(var, new MutableObject<ILogicalExpression>(
+                new UnnestingFunctionCallExpression(
+                        FunctionUtils.getFunctionInfo(AsterixBuiltinFunctions.SCAN_COLLECTION),
+                        new MutableObject<ILogicalExpression>(argExpr))));
+        unnest.getInputs().addAll(assign.getInputs());
+        opRef.setValue(unnest);
+        context.computeAndSetTypeEnvironmentForOperator(unnest);
+        return true;
+    }
+}
diff --git a/asterix-algebra/src/main/java/edu/uci/ics/asterix/translator/AqlExpressionToPlanTranslator.java b/asterix-algebra/src/main/java/edu/uci/ics/asterix/translator/AqlExpressionToPlanTranslator.java
index a2545ff..fc4bb03d7 100644
--- a/asterix-algebra/src/main/java/edu/uci/ics/asterix/translator/AqlExpressionToPlanTranslator.java
+++ b/asterix-algebra/src/main/java/edu/uci/ics/asterix/translator/AqlExpressionToPlanTranslator.java
@@ -187,13 +187,13 @@
         ILogicalOperator topOp = p.first;
         ProjectOperator project = (ProjectOperator) topOp;
         LogicalVariable resVar = project.getVariables().get(0);
+
         if (outputDatasetName == null) {
             FileSplit outputFileSplit = metadataProvider.getOutputFile();
             if (outputFileSplit == null) {
                 outputFileSplit = getDefaultOutputFileLocation();
             }
             metadataProvider.setOutputFile(outputFileSplit);
-            String resultNodeName = outputFileSplit.getNodeName();
 
             List<Mutable<ILogicalExpression>> writeExprList = new ArrayList<Mutable<ILogicalExpression>>(1);
             writeExprList.add(new MutableObject<ILogicalExpression>(new VariableReferenceExpression(resVar)));
@@ -202,6 +202,20 @@
             topOp = new DistributeResultOperator(writeExprList, sink);
             topOp.getInputs().add(new MutableObject<ILogicalOperator>(project));
         } else {
+            /** add the collection-to-sequence right before the final project, because dataset only accept non-collection records */
+            LogicalVariable seqVar = context.newVar();
+            @SuppressWarnings("unchecked")
+            /** This assign adds a marker function collection-to-sequence: if the input is a singleton collection, unnest it; otherwise do nothing. */
+            AssignOperator assignCollectionToSequence = new AssignOperator(seqVar,
+                    new MutableObject<ILogicalExpression>(
+                            new ScalarFunctionCallExpression(AsterixBuiltinFunctions
+                                    .getAsterixFunctionInfo(AsterixBuiltinFunctions.COLLECTION_TO_SEQUENCE),
+                                    new MutableObject<ILogicalExpression>(new VariableReferenceExpression(resVar)))));
+            assignCollectionToSequence.getInputs().add(
+                    new MutableObject<ILogicalOperator>(project.getInputs().get(0).getValue()));
+            project.getInputs().get(0).setValue(assignCollectionToSequence);
+            project.getVariables().set(0, seqVar);
+            resVar = seqVar;
 
             AqlDataSource targetDatasource = validateDatasetInfo(metadataProvider, stmt.getDataverseName(),
                     stmt.getDatasetName());
@@ -225,7 +239,6 @@
             }
             AssignOperator assign = new AssignOperator(vars, exprs);
             assign.getInputs().add(new MutableObject<ILogicalOperator>(project));
-
             Mutable<ILogicalExpression> varRef = new MutableObject<ILogicalExpression>(new VariableReferenceExpression(
                     resVar));
             ILogicalOperator leafOperator = null;
diff --git a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/APIFramework.java b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/APIFramework.java
index d72ba6a..d5d7409 100644
--- a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/APIFramework.java
+++ b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/APIFramework.java
@@ -136,12 +136,12 @@
         }
 
         @Override
-        public IOptimizationContext createOptimizationContext(int varCounter, int frameSize,
+        public IOptimizationContext createOptimizationContext(int varCounter,
                 IExpressionEvalSizeComputer expressionEvalSizeComputer,
                 IMergeAggregationExpressionFactory mergeAggregationExpressionFactory,
                 IExpressionTypeComputer expressionTypeComputer, INullableTypeComputer nullableTypeComputer,
                 PhysicalOptimizationConfig physicalOptimizationConfig) {
-            return new AlgebricksOptimizationContext(varCounter, frameSize, expressionEvalSizeComputer,
+            return new AlgebricksOptimizationContext(varCounter, expressionEvalSizeComputer,
                     mergeAggregationExpressionFactory, expressionTypeComputer, nullableTypeComputer,
                     physicalOptimizationConfig);
         }
@@ -260,22 +260,26 @@
 
         AsterixCompilerProperties compilerProperties = AsterixAppContextInfo.getInstance().getCompilerProperties();
         int frameSize = compilerProperties.getFrameSize();
+        int sortFrameLimit = (int) (compilerProperties.getSortMemorySize() / frameSize);
+        int joinFrameLimit = (int) (compilerProperties.getJoinMemorySize() / frameSize);
+        OptimizationConfUtil.getPhysicalOptimizationConfig().setFrameSize(frameSize);
+        OptimizationConfUtil.getPhysicalOptimizationConfig().setMaxFramesExternalSort(sortFrameLimit);
+        OptimizationConfUtil.getPhysicalOptimizationConfig().setMaxFramesHybridHash(joinFrameLimit);
+        
 
         HeuristicCompilerFactoryBuilder builder = new HeuristicCompilerFactoryBuilder(
                 AqlOptimizationContextFactory.INSTANCE);
+        builder.setPhysicalOptimizationConfig(OptimizationConfUtil.getPhysicalOptimizationConfig());
         builder.setLogicalRewrites(buildDefaultLogicalRewrites());
         builder.setPhysicalRewrites(buildDefaultPhysicalRewrites());
         IDataFormat format = queryMetadataProvider.getFormat();
         ICompilerFactory compilerFactory = builder.create();
-        builder.setFrameSize(frameSize);
         builder.setExpressionEvalSizeComputer(format.getExpressionEvalSizeComputer());
         builder.setIMergeAggregationExpressionFactory(new AqlMergeAggregationExpressionFactory());
         builder.setPartialAggregationTypeComputer(new AqlPartialAggregationTypeComputer());
         builder.setExpressionTypeComputer(AqlExpressionTypeComputer.INSTANCE);
         builder.setNullableTypeComputer(AqlNullableTypeComputer.INSTANCE);
 
-        OptimizationConfUtil.getPhysicalOptimizationConfig().setFrameSize(frameSize);
-        builder.setPhysicalOptimizationConfig(OptimizationConfUtil.getPhysicalOptimizationConfig());
 
         ICompiler compiler = compilerFactory.createCompiler(plan, queryMetadataProvider, t.getVarCounter());
         if (pc.isOptimize()) {
diff --git a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
index 7a9ead4..9c04b80 100644
--- a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
+++ b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
@@ -105,7 +105,7 @@
         indexLifecycleManager = new DatasetLifecycleManager(storageProperties, localResourceRepository);
         IAsterixAppRuntimeContextProvider asterixAppRuntimeContextProvider = new AsterixAppRuntimeContextProviderForRecovery(
                 this);
-        txnSubsystem = new TransactionSubsystem(ncApplicationContext.getNodeId(), asterixAppRuntimeContextProvider);
+        txnSubsystem = new TransactionSubsystem(ncApplicationContext.getNodeId(), asterixAppRuntimeContextProvider, txnProperties);
         isShuttingdown = false;
 
         // The order of registration is important. The buffer cache must registered before recovery and transaction managers.
diff --git a/asterix-app/src/main/resources/asterix-build-configuration.xml b/asterix-app/src/main/resources/asterix-build-configuration.xml
index 3e1b4b2..dc77a96 100644
--- a/asterix-app/src/main/resources/asterix-build-configuration.xml
+++ b/asterix-app/src/main/resources/asterix-build-configuration.xml
@@ -13,4 +13,9 @@
      <value>WARNING</value>
      <description>Log level for running tests/build</description>
   </property>
+  <property>
+     <name>txn.log.groupcommitinterval</name>
+     <value>1</value>
+     <description>The group commit wait time in milliseconds.</description>
+  </property>
 </asterixConfiguration>
diff --git a/asterix-app/src/main/resources/log.properties b/asterix-app/src/main/resources/log.properties
deleted file mode 100644
index ee8040a..0000000
--- a/asterix-app/src/main/resources/log.properties
+++ /dev/null
@@ -1 +0,0 @@
-group_commit_wait_period=1
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-delete-all.plan b/asterix-app/src/test/resources/optimizerts/results/scan-delete-all.plan
index e969e5d..cba987c 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-delete-all.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-delete-all.plan
@@ -3,8 +3,8 @@
     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
       -- INSERT_DELETE  |PARTITIONED|
         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-          -- STABLE_SORT [$$19(ASC)]  |PARTITIONED|
-            -- HASH_PARTITION_EXCHANGE [$$19]  |PARTITIONED|
+          -- STABLE_SORT [$$20(ASC)]  |PARTITIONED|
+            -- HASH_PARTITION_EXCHANGE [$$20]  |PARTITIONED|
               -- ASSIGN  |PARTITIONED|
                 -- STREAM_PROJECT  |PARTITIONED|
                   -- ASSIGN  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan b/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
index 4f0d931..e1852af 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-delete-rtree-secondary-index.plan
@@ -10,8 +10,8 @@
                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                     -- INSERT_DELETE  |PARTITIONED|
                       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                        -- STABLE_SORT [$$14(ASC)]  |PARTITIONED|
-                          -- HASH_PARTITION_EXCHANGE [$$14]  |PARTITIONED|
+                        -- STABLE_SORT [$$15(ASC)]  |PARTITIONED|
+                          -- HASH_PARTITION_EXCHANGE [$$15]  |PARTITIONED|
                             -- ASSIGN  |PARTITIONED|
                               -- STREAM_PROJECT  |PARTITIONED|
                                 -- ASSIGN  |PARTITIONED|
@@ -20,4 +20,4 @@
                                       -- BTREE_SEARCH  |PARTITIONED|
                                         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                                           -- ASSIGN  |PARTITIONED|
-                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
\ No newline at end of file
+                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-delete.plan b/asterix-app/src/test/resources/optimizerts/results/scan-delete.plan
index 0608f69..a5265c8 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-delete.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-delete.plan
@@ -3,8 +3,8 @@
     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
       -- INSERT_DELETE  |PARTITIONED|
         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-          -- STABLE_SORT [$$21(ASC)]  |PARTITIONED|
-            -- HASH_PARTITION_EXCHANGE [$$21]  |PARTITIONED|
+          -- STABLE_SORT [$$22(ASC)]  |PARTITIONED|
+            -- HASH_PARTITION_EXCHANGE [$$22]  |PARTITIONED|
               -- ASSIGN  |PARTITIONED|
                 -- STREAM_PROJECT  |PARTITIONED|
                   -- ASSIGN  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-insert-secondary-index.plan b/asterix-app/src/test/resources/optimizerts/results/scan-insert-secondary-index.plan
index 1458c66..8057666 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-insert-secondary-index.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-insert-secondary-index.plan
@@ -13,8 +13,8 @@
                         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                           -- INSERT_DELETE  |PARTITIONED|
                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                              -- STABLE_SORT [$$6(ASC)]  |PARTITIONED|
-                                -- HASH_PARTITION_EXCHANGE [$$6]  |PARTITIONED|
+                              -- STABLE_SORT [$$7(ASC)]  |PARTITIONED|
+                                -- HASH_PARTITION_EXCHANGE [$$7]  |PARTITIONED|
                                   -- ASSIGN  |PARTITIONED|
                                     -- STREAM_PROJECT  |PARTITIONED|
                                       -- ASSIGN  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/scan-insert.plan b/asterix-app/src/test/resources/optimizerts/results/scan-insert.plan
index 0b756d9..51d3060 100644
--- a/asterix-app/src/test/resources/optimizerts/results/scan-insert.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/scan-insert.plan
@@ -3,8 +3,8 @@
     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
       -- INSERT_DELETE  |PARTITIONED|
         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-          -- STABLE_SORT [$$6(ASC)]  |PARTITIONED|
-            -- HASH_PARTITION_EXCHANGE [$$6]  |PARTITIONED|
+          -- STABLE_SORT [$$7(ASC)]  |PARTITIONED|
+            -- HASH_PARTITION_EXCHANGE [$$7]  |PARTITIONED|
               -- ASSIGN  |PARTITIONED|
                 -- STREAM_PROJECT  |PARTITIONED|
                   -- ASSIGN  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.1.ddl.aql b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.1.ddl.aql
new file mode 100644
index 0000000..6f7b5e0
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.1.ddl.aql
@@ -0,0 +1,25 @@
+/*
+ * Description  : This test case is to verify the fix for issue244
+ 				: https://code.google.com/p/asterixdb/issues/detail?id=244
+ * Expected Res : Success
+ * Date         : 4th June 2013
+ */
+
+
+drop dataverse test if exists;
+create dataverse test;
+
+use dataverse test;
+
+create type TypeA as open {
+    id : int32,
+    name : string
+}
+
+create dataset t1(TypeA) primary key id;
+
+create dataset t2(TypeA) primary key id;
+
+create function f1(){
+for $m in dataset('t1') return $m
+};
diff --git a/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.2.update.aql b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.2.update.aql
new file mode 100644
index 0000000..a7b9500
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.2.update.aql
@@ -0,0 +1,16 @@
+/*
+ * Description  : This test case is to verify the fix for issue244
+ 				: https://code.google.com/p/asterixdb/issues/detail?id=244
+ * Expected Res : Success
+ * Date         : 4th June 2013
+ */
+
+use dataverse test;
+ 
+insert into dataset t1({"id":21,"name":"John"});
+insert into dataset t1({"id":34,"name":"Bill"});
+insert into dataset t1({"id":41,"name":"Joy"});
+insert into dataset t1({"id":16,"name":"Sam"});
+insert into dataset t1({"id":67,"name":"Ravi"});
+
+insert into dataset t2(f1());
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.3.query.aql b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.3.query.aql
new file mode 100644
index 0000000..68e4679
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/queries/user-defined-functions/query-issue244/query-issue244.3.query.aql
@@ -0,0 +1,12 @@
+/*
+ * Description  : This test case is to verify the fix for issue244
+ 				: https://code.google.com/p/asterixdb/issues/detail?id=244
+ * Expected Res : Success
+ * Date         : 4th June 2013
+ */
+ 
+use dataverse test;
+ 
+for $l in dataset('t2')
+order by $l.id
+return $l;
diff --git a/asterix-app/src/test/resources/runtimets/results/user-defined-functions/query-issue244/query-issue244.1.adm b/asterix-app/src/test/resources/runtimets/results/user-defined-functions/query-issue244/query-issue244.1.adm
new file mode 100644
index 0000000..92f6371
--- /dev/null
+++ b/asterix-app/src/test/resources/runtimets/results/user-defined-functions/query-issue244/query-issue244.1.adm
@@ -0,0 +1,5 @@
+{ "id": 16, "name": "Sam" }
+{ "id": 21, "name": "John" }
+{ "id": 34, "name": "Bill" }
+{ "id": 41, "name": "Joy" }
+{ "id": 67, "name": "Ravi" }
diff --git a/asterix-app/src/test/resources/runtimets/testsuite.xml b/asterix-app/src/test/resources/runtimets/testsuite.xml
index 4713b2e..9711930 100644
--- a/asterix-app/src/test/resources/runtimets/testsuite.xml
+++ b/asterix-app/src/test/resources/runtimets/testsuite.xml
@@ -4182,6 +4182,11 @@
         <output-dir compare="Text">issue289_query</output-dir>
       </compilation-unit>
     </test-case>
+     <test-case FilePath="user-defined-functions">
+      <compilation-unit name="query-issue244">
+        <output-dir compare="Text">query-issue244</output-dir>
+      </compilation-unit>
+    </test-case>
   </test-group>
   <test-group name="hints">
     <test-case FilePath="hints">
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixStorageProperties.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixStorageProperties.java
index 253b30c..753778a 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixStorageProperties.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixStorageProperties.java
@@ -5,8 +5,8 @@
     private static final String STORAGE_BUFFERCACHE_PAGESIZE_KEY = "storage.buffercache.pagesize";
     private static int STORAGE_BUFFERCACHE_PAGESIZE_DEFAULT = (32 << 10); // 32KB
 
-    private static final String STORAGE_BUFFERCACHE_NUMPAGES_KEY = "storage.buffercache.numpages";
-    private static final int STORAGE_BUFFERCACHE_NUMPAGES_DEFAULT = 1024;
+    private static final String STORAGE_BUFFERCACHE_SIZE_KEY = "storage.buffercache.size";
+    private static final long STORAGE_BUFFERCACHE_SIZE_DEFAULT = (32 << 20); // 32 MB
 
     private static final String STORAGE_BUFFERCACHE_MAXOPENFILES_KEY = "storage.buffercache.maxopenfiles";
     private static int STORAGE_BUFFERCACHE_MAXOPENFILES_DEFAULT = Integer.MAX_VALUE;
@@ -15,7 +15,7 @@
     private static final int STORAGE_MEMORYCOMPONENT_PAGESIZE_DEFAULT = (32 << 10); // 32KB
 
     private static final String STORAGE_MEMORYCOMPONENT_NUMPAGES_KEY = "storage.memorycomponent.numpages";
-    private static final int STORAGE_MEMORYCOMPONENT_NUMPAGES_DEFAULT = 8; // ... so 32MB components
+    private static final int STORAGE_MEMORYCOMPONENT_NUMPAGES_DEFAULT = 1024; // ... so 32MB components
 
     private static final String STORAGE_MEMORYCOMPONENT_GLOBALBUDGET_KEY = "storage.memorycomponent.globalbudget";
     private static final long STORAGE_MEMORYCOMPONENT_GLOBALBUDGET_DEFAULT = 536870912; // 512MB
@@ -35,9 +35,13 @@
                 PropertyInterpreters.getIntegerPropertyInterpreter());
     }
 
+    public long getBufferCacheSize() {
+        return accessor.getProperty(STORAGE_BUFFERCACHE_SIZE_KEY, STORAGE_BUFFERCACHE_SIZE_DEFAULT,
+                PropertyInterpreters.getLongPropertyInterpreter());
+    }
+    
     public int getBufferCacheNumPages() {
-        return accessor.getProperty(STORAGE_BUFFERCACHE_NUMPAGES_KEY, STORAGE_BUFFERCACHE_NUMPAGES_DEFAULT,
-                PropertyInterpreters.getIntegerPropertyInterpreter());
+        return (int) (getBufferCacheSize() / getBufferCachePageSize());
     }
 
     public int getBufferCacheMaxOpenFiles() {
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixTransactionProperties.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixTransactionProperties.java
index d97e53b..0b6ea85 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixTransactionProperties.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/config/AsterixTransactionProperties.java
@@ -1,6 +1,9 @@
 package edu.uci.ics.asterix.common.config;
 
 public class AsterixTransactionProperties extends AbstractAsterixProperties {
+    private static final String TXN_LOG_DIRECTORY_KEY = "txn.log.directory";
+    private static final String TXN_LOG_DIRECTORY_DEFAULT = "asterix_logs/";
+    
     private static final String TXN_LOG_BUFFER_NUMPAGES_KEY = "txn.log.buffer.numpages";
     private static int TXN_LOG_BUFFER_NUMPAGES_DEFAULT = 8;
 
@@ -9,25 +12,46 @@
 
     private static final String TXN_LOG_PARTITIONSIZE_KEY = "txn.log.partitionsize";
     private static final long TXN_LOG_PARTITIONSIZE_DEFAULT = (2 << 30); // 2GB
+    
+    private static final String TXN_LOG_DISKSECTORSIZE_KEY = "txn.log.disksectorsize";
+    private static final int TXN_LOG_DISKSECTORSIZE_DEFAULT = 4096;
 
     private static final String TXN_LOG_GROUPCOMMITINTERVAL_KEY = "txn.log.groupcommitinterval";
-    private static int TXN_LOG_GROUPCOMMITINTERVAL_DEFAULT = 200; // 200ms
+    private static int TXN_LOG_GROUPCOMMITINTERVAL_DEFAULT = 10; // 0.1ms
 
     private static final String TXN_LOG_CHECKPOINT_LSNTHRESHOLD_KEY = "txn.log.checkpoint.lsnthreshold";
     private static final int TXN_LOG_CHECKPOINT_LSNTHRESHOLD_DEFAULT = (64 << 20); // 64M
 
     private static final String TXN_LOG_CHECKPOINT_POLLFREQUENCY_KEY = "txn.log.checkpoint.pollfrequency";
     private static int TXN_LOG_CHECKPOINT_POLLFREQUENCY_DEFAULT = 120; // 120s
+    
+    private static final String TXN_LOG_CHECKPOINT_HISTORY_KEY = "txn.log.checkpoint.history";
+    private static int TXN_LOG_CHECKPOINT_HISTORY_DEFAULT = 0;
 
     private static final String TXN_LOCK_ESCALATIONTHRESHOLD_KEY = "txn.lock.escalationthreshold";
     private static int TXN_LOCK_ESCALATIONTHRESHOLD_DEFAULT = 1000;
 
     private static final String TXN_LOCK_SHRINKTIMER_KEY = "txn.lock.shrinktimer";
-    private static int TXN_LOCK_SHRINKTIMER_DEFAULT = 120000; // 2m
+    private static int TXN_LOCK_SHRINKTIMER_DEFAULT = 5000; // 5s
+    
+    private static final String TXN_LOCK_TIMEOUT_WAITTHRESHOLD_KEY = "txn.lock.timeout.waitthreshold";
+    private static final int TXN_LOCK_TIMEOUT_WAITTHRESHOLD_DEFAULT = 60000; // 60s
+    
+    private static final String TXN_LOCK_TIMEOUT_SWEEPTHRESHOLD_KEY = "txn.lock.timeout.sweepthreshold";
+    private static final int TXN_LOCK_TIMEOUT_SWEEPTHRESHOLD_DEFAULT = 10000; // 10s
 
     public AsterixTransactionProperties(AsterixPropertiesAccessor accessor) {
         super(accessor);
     }
+    
+    public String getLogDirectory() {
+        String logDirectory = accessor.getProperty(TXN_LOG_DIRECTORY_KEY, TXN_LOG_DIRECTORY_DEFAULT,
+                PropertyInterpreters.getStringPropertyInterpreter());
+        if (!logDirectory.endsWith("/")) {
+            logDirectory += "/";
+        }
+        return logDirectory;
+    }
 
     public int getLogBufferNumPages() {
         return accessor.getProperty(TXN_LOG_BUFFER_NUMPAGES_KEY, TXN_LOG_BUFFER_NUMPAGES_DEFAULT,
@@ -43,6 +67,11 @@
         return accessor.getProperty(TXN_LOG_PARTITIONSIZE_KEY, TXN_LOG_PARTITIONSIZE_DEFAULT,
                 PropertyInterpreters.getLongPropertyInterpreter());
     }
+    
+    public int getLogDiskSectorSize() {
+        return accessor.getProperty(TXN_LOG_DISKSECTORSIZE_KEY, TXN_LOG_DISKSECTORSIZE_DEFAULT,
+                PropertyInterpreters.getIntegerPropertyInterpreter());
+    }
 
     public int getGroupCommitInterval() {
         return accessor.getProperty(TXN_LOG_GROUPCOMMITINTERVAL_KEY, TXN_LOG_GROUPCOMMITINTERVAL_DEFAULT,
@@ -59,6 +88,11 @@
                 PropertyInterpreters.getIntegerPropertyInterpreter());
     }
 
+    public int getCheckpointHistory() {
+        return accessor.getProperty(TXN_LOG_CHECKPOINT_HISTORY_KEY, TXN_LOG_CHECKPOINT_HISTORY_DEFAULT,
+                PropertyInterpreters.getIntegerPropertyInterpreter());
+    }
+    
     public int getEntityToDatasetLockEscalationThreshold() {
         return accessor.getProperty(TXN_LOCK_ESCALATIONTHRESHOLD_KEY, TXN_LOCK_ESCALATIONTHRESHOLD_DEFAULT,
                 PropertyInterpreters.getIntegerPropertyInterpreter());
@@ -68,5 +102,15 @@
         return accessor.getProperty(TXN_LOCK_SHRINKTIMER_KEY, TXN_LOCK_SHRINKTIMER_DEFAULT,
                 PropertyInterpreters.getIntegerPropertyInterpreter());
     }
+    
+    public int getTimeoutWaitThreshold() {
+        return accessor.getProperty(TXN_LOCK_TIMEOUT_WAITTHRESHOLD_KEY, TXN_LOCK_TIMEOUT_WAITTHRESHOLD_DEFAULT,
+                PropertyInterpreters.getIntegerPropertyInterpreter());
+    }
+    
+    public int getTimeoutSweepThreshold() {
+        return accessor.getProperty(TXN_LOCK_TIMEOUT_SWEEPTHRESHOLD_KEY, TXN_LOCK_TIMEOUT_SWEEPTHRESHOLD_DEFAULT,
+                PropertyInterpreters.getIntegerPropertyInterpreter());
+    }
 
 }
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/transactions/LogManagerProperties.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/transactions/LogManagerProperties.java
index 89816aa..9387687 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/transactions/LogManagerProperties.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/transactions/LogManagerProperties.java
@@ -15,28 +15,16 @@
 package edu.uci.ics.asterix.common.transactions;
 
 import java.io.Serializable;
-import java.util.Properties;
+
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 
 public class LogManagerProperties implements Serializable {
 
     private static final long serialVersionUID = 2084227360840799662L;
 
     public static final int LOG_MAGIC_NUMBER = 123456789;
-    public static final String LOG_DIR_SUFFIX_KEY = ".txnLogDir";
-    public static final String LOG_PAGE_SIZE_KEY = "log_page_size";
-    public static final String LOG_PARTITION_SIZE_KEY = "log_partition_size";
-    public static final String NUM_LOG_PAGES_KEY = "num_log_pages";
-    public static final String LOG_FILE_PREFIX_KEY = "log_file_prefix";
-    public static final String GROUP_COMMIT_WAIT_PERIOD_KEY = "group_commit_wait_period";
-    public static final String DISK_SECTOR_SIZE_KEY = "disk_sector_size";
-
-    private static final int DEFAULT_LOG_PAGE_SIZE = 128 * 1024; //128KB
-    private static final int DEFAULT_NUM_LOG_PAGES = 8;
-    private static final long DEFAULT_LOG_PARTITION_SIZE = (long) 1024 * 1024 * 1024 * 2; //2GB 
-    private static final long DEFAULT_GROUP_COMMIT_WAIT_PERIOD = 200; // time in millisec.
+    public static final String LOG_DIR_SUFFIX = ".txnLogDir";
     private static final String DEFAULT_LOG_FILE_PREFIX = "asterix_transaction_log";
-    private static final String DEFAULT_LOG_DIRECTORY = "asterix_logs/";
-    private static final int DEFAULT_DISK_SECTOR_SIZE = 4096;
 
     // follow the naming convention <logFilePrefix>_<number> where number starts from 0
     private final String logFilePrefix;
@@ -56,22 +44,19 @@
     // default disk sector size
     private final int diskSectorSize;
 
-    public LogManagerProperties(Properties properties, String nodeId) {
-        this.logDirKey = new String(nodeId + LOG_DIR_SUFFIX_KEY);
-        this.logPageSize = Integer.parseInt(properties.getProperty(LOG_PAGE_SIZE_KEY, "" + DEFAULT_LOG_PAGE_SIZE));
-        this.numLogPages = Integer.parseInt(properties.getProperty(NUM_LOG_PAGES_KEY, "" + DEFAULT_NUM_LOG_PAGES));
-        long logPartitionSize = Long.parseLong(properties.getProperty(LOG_PARTITION_SIZE_KEY, ""
-                + DEFAULT_LOG_PARTITION_SIZE));
-        this.logDir = properties.getProperty(logDirKey, DEFAULT_LOG_DIRECTORY + nodeId);
-        this.logFilePrefix = properties.getProperty(LOG_FILE_PREFIX_KEY, DEFAULT_LOG_FILE_PREFIX);
-        this.groupCommitWaitPeriod = Long.parseLong(properties.getProperty(GROUP_COMMIT_WAIT_PERIOD_KEY, ""
-                + DEFAULT_GROUP_COMMIT_WAIT_PERIOD));
+    public LogManagerProperties(AsterixTransactionProperties txnProperties, String nodeId) {
+        this.logDirKey = new String(nodeId + LOG_DIR_SUFFIX);
+        this.logPageSize = txnProperties.getLogBufferPageSize();
+        this.numLogPages = txnProperties.getLogBufferNumPages();
+        long logPartitionSize = txnProperties.getLogPartitionSize();
+        this.logDir = txnProperties.getLogDirectory() + nodeId;
+        this.logFilePrefix = DEFAULT_LOG_FILE_PREFIX;
+        this.groupCommitWaitPeriod = txnProperties.getGroupCommitInterval();
 
         this.logBufferSize = logPageSize * numLogPages;
         //make sure that the log partition size is the multiple of log buffer size.
         this.logPartitionSize = (logPartitionSize / logBufferSize) * logBufferSize;
-        this.diskSectorSize = Integer.parseInt(properties.getProperty(DISK_SECTOR_SIZE_KEY, ""
-                + DEFAULT_DISK_SECTOR_SIZE));
+        this.diskSectorSize = txnProperties.getLogDiskSectorSize();
     }
 
     public long getLogPartitionSize() {
diff --git a/asterix-common/src/test/java/edu/uci/ics/asterix/test/aql/TestsUtils.java b/asterix-common/src/test/java/edu/uci/ics/asterix/test/aql/TestsUtils.java
index ac8a3bd..d13dd2e 100644
--- a/asterix-common/src/test/java/edu/uci/ics/asterix/test/aql/TestsUtils.java
+++ b/asterix-common/src/test/java/edu/uci/ics/asterix/test/aql/TestsUtils.java
@@ -236,7 +236,7 @@
             GlobalConfig.ASTERIX_LOGGER.log(Level.SEVERE, "Method failed: " + method.getStatusLine());
             String[] errors = handleError(method);
             GlobalConfig.ASTERIX_LOGGER.log(Level.SEVERE, errors[2]);
-            throw new Exception("DDL operation failed: " + errors[0]);
+            throw new Exception("DML operation failed: " + errors[0]);
         }
     }
 
diff --git a/asterix-doc/src/site/markdown/aql/manual.md b/asterix-doc/src/site/markdown/aql/manual.md
index da51dee..f1c3fbd 100644
--- a/asterix-doc/src/site/markdown/aql/manual.md
+++ b/asterix-doc/src/site/markdown/aql/manual.md
@@ -601,14 +601,23 @@
 The following example creates an rtree index called fbSenderLocIdx on the sender-location field of the FacebookMessages dataset.
 This index can be useful for accelerating queries that use the
 [`spatial-intersect` function](functions.html#spatial-intersect) in a predicate involving the 
-sender-loction field.
+sender-location field.
 
 ##### Example
 
     create index fbSenderLocIndex on FacebookMessages(sender-location) type rtree;
 
+The following example creates a 3-gram index called fbUserIdx on the name field of the FacebookUsers dataset.
+This index can be used to accelerate some similarity or substring maching queries on the name field.
+For details refer to the [document on similarity queries](similarity.html#NGram_Index).
+
+##### Example
+
+    create index fbUserIdx on FacebookUsers(name) type ngram(3);
+
 The following example creates a keyword index called fbMessageIdx on the message field of the FacebookMessages dataset.
-This index can be useful for accelerating text searches involving the message field.
+This keyword index can be used to optimize queries with token-based similarity predicates on the message field.
+For details refer to the [document on similarity queries](similarity.html#Keyword_Index).
 
 ##### Example
 
diff --git a/asterix-doc/src/site/resources/images/hyrax_ts.png b/asterix-doc/src/site/resources/images/hyrax_ts.png
new file mode 100644
index 0000000..001c788
--- /dev/null
+++ b/asterix-doc/src/site/resources/images/hyrax_ts.png
Binary files differ
diff --git a/asterix-doc/src/site/site.xml b/asterix-doc/src/site/site.xml
index b68941c..017bf10 100644
--- a/asterix-doc/src/site/site.xml
+++ b/asterix-doc/src/site/site.xml
@@ -11,7 +11,11 @@
   
   <version position="right"/>
 
-  <poweredBy><logo name="" img=""/></poweredBy>
+  <poweredBy>
+    <logo name="Hyracks"
+          href="https://code.google.com/p/hyracks/"
+          img="images/hyrax_ts.png"/>
+  </poweredBy>
 
   <skin>
     <groupId>org.apache.maven.skins</groupId>
diff --git a/asterix-installer/src/main/resources/conf/asterix-configuration.xml b/asterix-installer/src/main/resources/conf/asterix-configuration.xml
index f0d76bf..8394a96 100644
--- a/asterix-installer/src/main/resources/conf/asterix-configuration.xml
+++ b/asterix-installer/src/main/resources/conf/asterix-configuration.xml
@@ -22,10 +22,11 @@
 	</property>
 
 	<property>
-		<name>storage.buffercache.numpages</name>
-		<value>1024</value>
-		<description>The number of pages allocated to the disk buffer cache.
-			(Default = "1024")
+		<name>storage.buffercache.size</name>
+		<value>33554432</value>
+		<description>The size of memory allocated to the disk buffer cache.
+			The value should be a multiple of the buffer cache page size(Default
+			= "33554432" // 32MB)
 		</description>
 	</property>
 
@@ -79,6 +80,14 @@
 	</property>
 
 	<property>
+		<name>txn.log.directory</name>
+		<value>asterix_logs/</value>
+		<description>The directory location for transaction logs. (Default =
+			"asterix_logs/")
+		</description>
+	</property>
+
+	<property>
 		<name>txn.log.buffer.numpages</name>
 		<value>8</value>
 		<description>The number of in-memory log buffer pages. (Default = "8")
@@ -103,10 +112,17 @@
 	</property>
 
 	<property>
+		<name>txn.log.disksectorsize</name>
+		<value>4096</value>
+		<description>The size of a disk sector. (Default = "4096")
+		</description>
+	</property>
+
+	<property>
 		<name>txn.log.groupcommitinterval</name>
-		<value>200</value>
+		<value>1</value>
 		<description>The group commit wait time in milliseconds. (Default =
-			"200" // 2ms)
+			"10" // 0.1ms)
 		</description>
 	</property>
 
@@ -127,6 +143,14 @@
 	</property>
 
 	<property>
+		<name>txn.log.checkpoint.history</name>
+		<value>0</value>
+		<description>The number of old log partition files to keep before
+			discarding. (Default = "0")
+		</description>
+	</property>
+
+	<property>
 		<name>txn.lock.escalationthreshold</name>
 		<value>1000</value>
 		<description>The number of entity level locks that need to be acquired
@@ -137,9 +161,26 @@
 
 	<property>
 		<name>txn.lock.shrinktimer</name>
-		<value>120000</value>
+		<value>5000</value>
 		<description>The time in milliseconds to wait before deallocating
-			unused lock manager memory. (Default = "120000" // 120s)
+			unused lock manager memory. (Default = "5000" // 5s)
+		</description>
+	</property>
+
+	<property>
+		<name>txn.lock.timeout.waitthreshold</name>
+		<value>60000</value>
+		<description>The time in milliseconds to wait before labeling a
+			transaction which has been waiting for a lock timed-out. (Default =
+			"60000" // 60s)
+		</description>
+	</property>
+
+	<property>
+		<name>txn.lock.timeout.sweepthreshold</name>
+		<value>10000</value>
+		<description>The time in milliseconds the timeout thread waits between
+			sweeps to detect timed-out transactions. (Default = "10000" // 10s)
 		</description>
 	</property>
 
@@ -176,8 +217,8 @@
 
 	<property>
 		<name>api.port</name>
-		<value>19101</value>
-		<description>The port for the ASTERIX API server. (Default = 19101)
+		<value>19002</value>
+		<description>The port for the ASTERIX API server. (Default = 19002)
 		</description>
 	</property>
 
diff --git a/asterix-om/src/main/java/edu/uci/ics/asterix/om/functions/AsterixBuiltinFunctions.java b/asterix-om/src/main/java/edu/uci/ics/asterix/om/functions/AsterixBuiltinFunctions.java
index 2a732ac..f717653 100644
--- a/asterix-om/src/main/java/edu/uci/ics/asterix/om/functions/AsterixBuiltinFunctions.java
+++ b/asterix-om/src/main/java/edu/uci/ics/asterix/om/functions/AsterixBuiltinFunctions.java
@@ -31,6 +31,7 @@
 import edu.uci.ics.asterix.om.typecomputer.impl.CastListResultTypeComputer;
 import edu.uci.ics.asterix.om.typecomputer.impl.CastRecordResultTypeComputer;
 import edu.uci.ics.asterix.om.typecomputer.impl.ClosedRecordConstructorResultType;
+import edu.uci.ics.asterix.om.typecomputer.impl.CollectionToSequenceTypeComputer;
 import edu.uci.ics.asterix.om.typecomputer.impl.ConcatNonNullTypeComputer;
 import edu.uci.ics.asterix.om.typecomputer.impl.FieldAccessByIndexResultType;
 import edu.uci.ics.asterix.om.typecomputer.impl.InjectFailureTypeComputer;
@@ -561,6 +562,8 @@
 
     public static final FunctionIdentifier NOT_NULL = new FunctionIdentifier(FunctionConstants.ASTERIX_NS, "not-null",
             1);
+    public static final FunctionIdentifier COLLECTION_TO_SEQUENCE = new FunctionIdentifier(
+            FunctionConstants.ASTERIX_NS, "" + "collection-to-sequence", 1);
 
     public static IFunctionInfo getAsterixFunctionInfo(FunctionIdentifier fid) {
         IFunctionInfo finfo = registeredFunctions.get(fid);
@@ -862,6 +865,8 @@
         addFunction(INTERVAL_CONSTRUCTOR_START_FROM_DATETIME, OptionalAIntervalTypeComputer.INSTANCE);
         addFunction(INTERVAL_CONSTRUCTOR_START_FROM_TIME, OptionalAIntervalTypeComputer.INSTANCE);
 
+        addPrivateFunction(COLLECTION_TO_SEQUENCE, CollectionToSequenceTypeComputer.INSTANCE);
+
         String metadataFunctionLoaderClassName = "edu.uci.ics.asterix.metadata.functions.MetadataBuiltinFunctions";
         try {
             Class.forName(metadataFunctionLoaderClassName);
diff --git a/asterix-om/src/main/java/edu/uci/ics/asterix/om/typecomputer/impl/CollectionToSequenceTypeComputer.java b/asterix-om/src/main/java/edu/uci/ics/asterix/om/typecomputer/impl/CollectionToSequenceTypeComputer.java
new file mode 100644
index 0000000..5066d4b
--- /dev/null
+++ b/asterix-om/src/main/java/edu/uci/ics/asterix/om/typecomputer/impl/CollectionToSequenceTypeComputer.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2009-2013 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.asterix.om.typecomputer.impl;
+
+import edu.uci.ics.asterix.om.typecomputer.base.IResultTypeComputer;
+import edu.uci.ics.asterix.om.types.ATypeTag;
+import edu.uci.ics.asterix.om.types.AbstractCollectionType;
+import edu.uci.ics.asterix.om.types.IAType;
+import edu.uci.ics.asterix.om.types.TypeHelper;
+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.expressions.AbstractFunctionCallExpression;
+import edu.uci.ics.hyracks.algebricks.core.algebra.expressions.IVariableTypeEnvironment;
+import edu.uci.ics.hyracks.algebricks.core.algebra.metadata.IMetadataProvider;
+
+/**
+ * This function is to make a sequence of records and a singleton collection of records
+ * present in a uniformed manner.
+ * 
+ * @author yingyib
+ */
+public class CollectionToSequenceTypeComputer implements IResultTypeComputer {
+
+    public static final CollectionToSequenceTypeComputer INSTANCE = new CollectionToSequenceTypeComputer();
+
+    @Override
+    public IAType computeType(ILogicalExpression expression, IVariableTypeEnvironment env,
+            IMetadataProvider<?, ?> metadataProvider) throws AlgebricksException {
+        AbstractFunctionCallExpression func = (AbstractFunctionCallExpression) expression;
+        ILogicalExpression arg = func.getArguments().get(0).getValue();
+
+        IAType argType = (IAType) env.getType(arg);
+        if (TypeHelper.canBeNull(argType)) {
+            IAType nonOptionalType = TypeHelper.getNonOptionalType(argType);
+            if (nonOptionalType.getTypeTag() == ATypeTag.ORDEREDLIST
+                    || nonOptionalType.getTypeTag() == ATypeTag.UNORDEREDLIST) {
+                /** if the collection is null, that corresponds to an empty sequence */
+                argType = nonOptionalType;
+            }
+        }
+
+        ATypeTag argTypeTag = argType.getTypeTag();
+        if (argTypeTag == ATypeTag.ORDEREDLIST || argTypeTag == ATypeTag.UNORDEREDLIST) {
+            /** if the input is a singleton list, return it's item type if any */
+            AbstractCollectionType collectionType = (AbstractCollectionType) argType;
+            return collectionType.getItemType();
+        } else {
+            /** if the input is not a singleton list, return the original input type */
+            return argType;
+        }
+    }
+
+}
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/EntityInfoManager.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/EntityInfoManager.java
index 206a3bf..1e944bc 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/EntityInfoManager.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/EntityInfoManager.java
@@ -30,13 +30,12 @@
  */
 public class EntityInfoManager {
 
-    public static final int SHRINK_TIMER_THRESHOLD = 120000; //2min
-
     private ArrayList<ChildEntityInfoArrayManager> pArray;
     private int allocChild; //used to allocate the next free EntityInfo slot.
     private long shrinkTimer;
     private boolean isShrinkTimerOn;
     private int occupiedSlots;
+    private int shrinkTimerThreshold;
 
     //    ////////////////////////////////////////////////
     //    // begin of unit test
@@ -129,12 +128,13 @@
     //    // end of unit test
     //    ////////////////////////////////////////////////
 
-    public EntityInfoManager() {
+    public EntityInfoManager(int shrinkTimerThreshold) {
         pArray = new ArrayList<ChildEntityInfoArrayManager>();
         pArray.add(new ChildEntityInfoArrayManager());
         allocChild = 0;
         occupiedSlots = 0;
         isShrinkTimerOn = false;
+        this.shrinkTimerThreshold = shrinkTimerThreshold;
     }
 
     public int allocate(int jobId, int datasetId, int entityHashVal, byte lockMode) {
@@ -208,7 +208,7 @@
 
         if (size > 1 && size * ChildEntityInfoArrayManager.NUM_OF_SLOTS / usedSlots >= 3) {
             if (isShrinkTimerOn) {
-                if (System.currentTimeMillis() - shrinkTimer >= SHRINK_TIMER_THRESHOLD) {
+                if (System.currentTimeMillis() - shrinkTimer >= shrinkTimerThreshold) {
                     isShrinkTimerOn = false;
                     return true;
                 }
@@ -301,7 +301,7 @@
     }
     
     public int getShrinkTimerThreshold() {
-        return SHRINK_TIMER_THRESHOLD;
+        return shrinkTimerThreshold;
     }
 
     public void initEntityInfo(int slotNum, int jobId, int datasetId, int PKHashVal, byte lockMode) {
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/JobInfo.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/JobInfo.java
index 8bf5304..86eb02b 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/JobInfo.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/JobInfo.java
@@ -192,9 +192,9 @@
         }
     }
 
-    public void decreaseDatasetISLockCount(int datasetId) {
+    public void decreaseDatasetISLockCount(int datasetId, int entityToDatasetLockEscalationThreshold) {
         int count = datasetISLockHT.get(datasetId);
-        if (count >= LockManager.ESCALATE_TRHESHOLD_ENTITY_TO_DATASET) {
+        if (count >= entityToDatasetLockEscalationThreshold) {
             //do not decrease the count since it is already escalated.
         } else if (count > 1) {
             datasetISLockHT.upsert(datasetId, count - 1);
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManager.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManager.java
index 96e95d9..9768198 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManager.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManager.java
@@ -25,6 +25,7 @@
 import java.util.concurrent.locks.ReadWriteLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
 import edu.uci.ics.asterix.common.transactions.DatasetId;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
@@ -56,8 +57,6 @@
     public static final boolean ALLOW_DATASET_GRANULE_X_LOCK_WITH_OTHER_CONCURRENT_LOCK_REQUESTS = false;
 
     public static final boolean ALLOW_ESCALATE_FROM_ENTITY_TO_DATASET = true;
-    //Threshold must be greater than 1 and should be reasonably large enough not to escalate too soon.
-    public static final int ESCALATE_TRHESHOLD_ENTITY_TO_DATASET = 1000;
     private static final int DO_ESCALATE = 0;
     private static final int ESCALATED = 1;
     private static final int DONOT_ESCALATE = 2;
@@ -95,7 +94,7 @@
         this.waiterLatch = new ReentrantReadWriteLock(true);
         this.jobHT = new HashMap<JobId, JobInfo>();
         this.datasetResourceHT = new HashMap<DatasetId, DatasetLockInfo>();
-        this.entityInfoManager = new EntityInfoManager();
+        this.entityInfoManager = new EntityInfoManager(txnSubsystem.getTransactionProperties().getLockManagerShrinkTimer());
         this.lockWaiterManager = new LockWaiterManager();
         this.entityLockInfoManager = new EntityLockInfoManager(entityInfoManager, lockWaiterManager);
         this.deadlockDetector = new DeadlockDetector(jobHT, datasetResourceHT, entityLockInfoManager,
@@ -110,6 +109,10 @@
             this.lockRequestTracker = new LockRequestTracker();
         }
     }
+     
+    public AsterixTransactionProperties getTransactionProperties() {
+        return this.txnSubsystem.getTransactionProperties();
+    }
 
     @Override
     public void lock(DatasetId datasetId, int entityHashValue, byte lockMode, ITransactionContext txnContext)
@@ -197,7 +200,7 @@
                         if (doEscalate) {
                             throw new IllegalStateException(
                                     "ESCALATE_TRHESHOLD_ENTITY_TO_DATASET should not be set to "
-                                            + ESCALATE_TRHESHOLD_ENTITY_TO_DATASET);
+                                            + txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold());
                         }
                     }
                 }
@@ -291,9 +294,9 @@
         }
 
         int count = jobInfo.getDatasetISLockCount(datasetId);
-        if (count == ESCALATE_TRHESHOLD_ENTITY_TO_DATASET) {
+        if (count == txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold()) {
             return DO_ESCALATE;
-        } else if (count > ESCALATE_TRHESHOLD_ENTITY_TO_DATASET) {
+        } else if (count > txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold()) {
             return ESCALATED;
         } else {
             return DONOT_ESCALATE;
@@ -779,7 +782,7 @@
 
             if (ALLOW_ESCALATE_FROM_ENTITY_TO_DATASET) {
                 if (!isInstant && datasetLockMode == LockMode.IS) {
-                    jobInfo.decreaseDatasetISLockCount(datasetId.getId());
+                    jobInfo.decreaseDatasetISLockCount(datasetId.getId(), txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold());
                 }
             }
 
@@ -1294,7 +1297,7 @@
                             //We don't want to allow the lock escalation when there is a first lock request on a dataset. 
                             throw new IllegalStateException(
                                     "ESCALATE_TRHESHOLD_ENTITY_TO_DATASET should not be set to "
-                                            + ESCALATE_TRHESHOLD_ENTITY_TO_DATASET);
+                                            + txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold());
                         }
                     }
                 }
@@ -2094,7 +2097,7 @@
         try {
             StringBuilder sb = new StringBuilder();
             sb.append("\n>>dump_begin\t>>----- [ConfVars] -----");
-            sb.append("\nESCALATE_TRHESHOLD_ENTITY_TO_DATASET: " + ESCALATE_TRHESHOLD_ENTITY_TO_DATASET);
+            sb.append("\nESCALATE_TRHESHOLD_ENTITY_TO_DATASET: " + txnSubsystem.getTransactionProperties().getEntityToDatasetLockEscalationThreshold());
             sb.append("\nSHRINK_TIMER_THRESHOLD (entityLockInfoManager): "
                     + entityLockInfoManager.getShrinkTimerThreshold());
             sb.append("\nSHRINK_TIMER_THRESHOLD (entityInfoManager): " + entityInfoManager.getShrinkTimerThreshold());
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerDeterministicUnitTest.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerDeterministicUnitTest.java
index 0781276..02fda06 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerDeterministicUnitTest.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerDeterministicUnitTest.java
@@ -7,7 +7,14 @@
 import java.util.NoSuchElementException;
 import java.util.Scanner;
 
+import edu.uci.ics.asterix.common.config.AsterixCompilerProperties;
+import edu.uci.ics.asterix.common.config.AsterixExternalProperties;
+import edu.uci.ics.asterix.common.config.AsterixMetadataProperties;
+import edu.uci.ics.asterix.common.config.AsterixPropertiesAccessor;
+import edu.uci.ics.asterix.common.config.AsterixStorageProperties;
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
+import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.DatasetId;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
 import edu.uci.ics.asterix.common.transactions.ITransactionManager.TransactionState;
@@ -18,7 +25,7 @@
 
 public class LockManagerDeterministicUnitTest {
 
-    public static void main(String args[]) throws ACIDException, IOException {
+    public static void main(String args[]) throws ACIDException, IOException, AsterixException {
         //initialize controller thread
         String requestFileName = new String(
                 "src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockRequestFile");
@@ -39,8 +46,9 @@
     String requestFileName;
     long defaultWaitTime;
 
-    public LockRequestController(String requestFileName) throws ACIDException {
-        this.txnProvider = new TransactionSubsystem("LockManagerPredefinedUnitTest", null);;
+    public LockRequestController(String requestFileName) throws ACIDException, AsterixException {
+        this.txnProvider = new TransactionSubsystem("LockManagerPredefinedUnitTest", null,
+                new AsterixTransactionProperties(new AsterixPropertiesAccessor()));
         this.workerReadyQueue = new WorkerReadyQueue();
         this.requestList = new ArrayList<LockRequest>();
         this.expectedResultList = new ArrayList<ArrayList<Integer>>();
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerRandomUnitTest.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerRandomUnitTest.java
index b2cc6ab..a942325 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerRandomUnitTest.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/LockManagerRandomUnitTest.java
@@ -3,7 +3,10 @@
 import java.util.ArrayList;
 import java.util.Random;
 
+import edu.uci.ics.asterix.common.config.AsterixPropertiesAccessor;
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
+import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.DatasetId;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
 import edu.uci.ics.asterix.common.transactions.ITransactionContext;
@@ -28,9 +31,10 @@
     private static int jobId = 0;
     private static Random rand;
 
-    public static void main(String args[]) throws ACIDException {
+    public static void main(String args[]) throws ACIDException, AsterixException {
         int i;
-        TransactionSubsystem txnProvider = new TransactionSubsystem("LockManagerRandomUnitTest", null);
+        TransactionSubsystem txnProvider = new TransactionSubsystem("LockManagerRandomUnitTest", null,
+                new AsterixTransactionProperties(new AsterixPropertiesAccessor()));
         rand = new Random(System.currentTimeMillis());
         for (i = 0; i < MAX_NUM_OF_ENTITY_LOCK_JOB; i++) {
             System.out.println("Creating " + i + "th EntityLockJob..");
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/TimeOutDetector.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/TimeOutDetector.java
index 05052f0..7cbd193 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/TimeOutDetector.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/locking/TimeOutDetector.java
@@ -15,17 +15,19 @@
  */
 
 public class TimeOutDetector {
-    static final long TIME_OUT_THRESHOLD = 60000;
-    static final long SWEEP_PERIOD = 10000;//120000;
 
     LockManager lockMgr;
     Thread trigger;
     LinkedList<LockWaiter> victimList;
+    int timeoutThreshold;
+    int sweepThreshold;
 
     public TimeOutDetector(LockManager lockMgr) {
         this.victimList = new LinkedList<LockWaiter>();
         this.lockMgr = lockMgr;
         this.trigger = new Thread(new TimeoutTrigger(this));
+        this.timeoutThreshold = lockMgr.getTransactionProperties().getTimeoutWaitThreshold();
+        this.sweepThreshold = lockMgr.getTransactionProperties().getTimeoutSweepThreshold();
         trigger.setDaemon(true);
         AsterixThreadExecutor.INSTANCE.execute(trigger);
     }
@@ -39,7 +41,7 @@
     }
 
     public void checkAndSetVictim(LockWaiter waiterObj) {
-        if (System.currentTimeMillis() - waiterObj.getBeginWaitTime() >= TIME_OUT_THRESHOLD) {
+        if (System.currentTimeMillis() - waiterObj.getBeginWaitTime() >= timeoutThreshold) {
             waiterObj.setVictim(true);
             waiterObj.setWait(false);
             victimList.add(waiterObj);
@@ -68,7 +70,7 @@
     public void run() {
         while (true) {
             try {
-                Thread.sleep(TimeOutDetector.SWEEP_PERIOD);
+                Thread.sleep(owner.sweepThreshold);
                 owner.sweep(); // Trigger the timeout detector (the owner) to
                                // initiate sweep
             } catch (InterruptedException e) {
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/logging/LogManager.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/logging/LogManager.java
index d4f874b..ba7e093 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/logging/LogManager.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/logging/LogManager.java
@@ -113,7 +113,7 @@
 
     public LogManager(TransactionSubsystem provider) throws ACIDException {
         this.provider = provider;
-        initLogManagerProperties(this.provider.getId());
+        logManagerProperties = new LogManagerProperties(this.provider.getTransactionProperties(), this.provider.getId());
         logPageSize = logManagerProperties.getLogPageSize();
         initLogManager();
         statLogSize = 0;
@@ -122,43 +122,13 @@
 
     public LogManager(TransactionSubsystem provider, String nodeId) throws ACIDException {
         this.provider = provider;
-        initLogManagerProperties(nodeId);
+        logManagerProperties = new LogManagerProperties(provider.getTransactionProperties(), nodeId);
         logPageSize = logManagerProperties.getLogPageSize();
         initLogManager();
         statLogSize = 0;
         statLogCount = 0;
     }
 
-    /*
-     * initialize the log manager properties either from the configuration file
-     * on disk or with default values
-     */
-    private void initLogManagerProperties(String nodeId) throws ACIDException {
-        LogManagerProperties logProperties = null;
-        InputStream is = null;
-        try {
-            is = this.getClass().getClassLoader()
-                    .getResourceAsStream(TransactionManagementConstants.LogManagerConstants.LOG_CONF_FILE);
-
-            Properties p = new Properties();
-
-            if (is != null) {
-                p.load(is);
-            }
-            logProperties = new LogManagerProperties(p, nodeId);
-
-        } catch (IOException ioe) {
-            if (is != null) {
-                try {
-                    is.close();
-                } catch (IOException e) {
-                    throw new ACIDException("unable to close input stream ", e);
-                }
-            }
-        }
-        logManagerProperties = logProperties;
-    }
-
     private void initLogManager() throws ACIDException {
         logRecordHelper = new LogRecordHelper(this);
         numLogPages = logManagerProperties.getNumLogPages();
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/CheckpointThread.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/CheckpointThread.java
index b59c48f..68df619 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/CheckpointThread.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/CheckpointThread.java
@@ -11,8 +11,8 @@
 
 public class CheckpointThread extends Thread {
 
-    private static final long LSN_THRESHOLD = 64 * 1024 * 1024;
-    private long checkpointTermInSecs = 120; //seconds.
+    private long lsnThreshold;
+    private long checkpointTermInSecs;
 
     private long lastMinMCTFirstLSN = 0;
 
@@ -20,12 +20,11 @@
     private final IIndexLifecycleManager indexLifecycleManager;
 
     public CheckpointThread(IRecoveryManager recoveryMgr, IIndexLifecycleManager indexLifecycleManager,
-            long checkpointTermInSecs) {
+            long lsnThreshold, long checkpointTermInSecs) {
         this.recoveryMgr = recoveryMgr;
         this.indexLifecycleManager = indexLifecycleManager;
-        if (this.checkpointTermInSecs < checkpointTermInSecs) {
-            this.checkpointTermInSecs = checkpointTermInSecs;
-        }
+        this.lsnThreshold = lsnThreshold;
+        this.checkpointTermInSecs = checkpointTermInSecs;
     }
 
     @Override
@@ -39,7 +38,7 @@
             }
 
             currentMinMCTFirstLSN = getMinMCTFirstLSN();
-            if (currentMinMCTFirstLSN - lastMinMCTFirstLSN > LSN_THRESHOLD) {
+            if (currentMinMCTFirstLSN - lastMinMCTFirstLSN > lsnThreshold) {
                 try {
                     recoveryMgr.checkpoint(false);
                     lastMinMCTFirstLSN = currentMinMCTFirstLSN;
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/RecoveryManager.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/RecoveryManager.java
index ee27061..7b95358 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/RecoveryManager.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/recovery/RecoveryManager.java
@@ -24,6 +24,7 @@
 import java.io.ObjectOutputStream;
 import java.io.OutputStream;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -90,6 +91,7 @@
     public static final boolean IS_DEBUG_MODE = false;//true
     private static final Logger LOGGER = Logger.getLogger(RecoveryManager.class.getName());
     private final TransactionSubsystem txnSubsystem;
+    private final int checkpointHistory;
 
     /**
      * A file at a known location that contains the LSN of the last log record
@@ -100,6 +102,7 @@
 
     public RecoveryManager(TransactionSubsystem TransactionProvider) throws ACIDException {
         this.txnSubsystem = TransactionProvider;
+        this.checkpointHistory = this.txnSubsystem.getTransactionProperties().getCheckpointHistory();
     }
 
     /**
@@ -516,8 +519,10 @@
 
         //#. delete the previous checkpoint files
         if (prevCheckpointFiles != null) {
-            for (File file : prevCheckpointFiles) {
-                file.delete();
+            // sort the filenames lexicographically to keep the latest checkpointHistory files.
+            Arrays.sort(prevCheckpointFiles);
+            for (int i = 0; i < prevCheckpointFiles.length - this.checkpointHistory; ++i) {
+                prevCheckpointFiles[i].delete();
             }
         }
 
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionManagementConstants.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionManagementConstants.java
index 7d04f61..25b9195 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionManagementConstants.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionManagementConstants.java
@@ -26,10 +26,6 @@
     }
 
     public static class LogManagerConstants {
-        public static final String LOG_CONF_DIR = "log_conf";
-        public static final String LOG_CONF_FILE = "log.properties";
-        public static final String ASTERIX_CONF_DIR = "src/main/resources";
-        public static final String DEFAULT_LOG_DIR = "asterix_logs";
         public static final int TERMINAL_LSN = -1;
     }
 
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionSubsystem.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionSubsystem.java
index eb6e9a2..bde44de 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionSubsystem.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionSubsystem.java
@@ -14,6 +14,7 @@
  */
 package edu.uci.ics.asterix.transaction.management.service.transaction;
 
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
 import edu.uci.ics.asterix.common.transactions.IAsterixAppRuntimeContextProvider;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
@@ -42,10 +43,12 @@
     private final IndexLoggerRepository loggerRepository;
     private final IAsterixAppRuntimeContextProvider asterixAppRuntimeContextProvider;
     private final CheckpointThread checkpointThread;
+    private final AsterixTransactionProperties txnProperties;
 
-    public TransactionSubsystem(String id, IAsterixAppRuntimeContextProvider asterixAppRuntimeContextProvider)
-            throws ACIDException {
+    public TransactionSubsystem(String id, IAsterixAppRuntimeContextProvider asterixAppRuntimeContextProvider,
+            AsterixTransactionProperties txnProperties) throws ACIDException {
         this.id = id;
+        this.txnProperties = txnProperties;
         this.transactionManager = new TransactionManager(this);
         this.logManager = new LogManager(this);
         this.lockManager = new LockManager(this);
@@ -55,7 +58,8 @@
         this.asterixAppRuntimeContextProvider = asterixAppRuntimeContextProvider;
         if (asterixAppRuntimeContextProvider != null) {
             this.checkpointThread = new CheckpointThread(recoveryManager,
-                    asterixAppRuntimeContextProvider.getIndexLifecycleManager(), 0);
+                    asterixAppRuntimeContextProvider.getIndexLifecycleManager(),
+                    this.txnProperties.getCheckpointLSNThreshold(), this.txnProperties.getCheckpointPollFrequency());
         } else {
             this.checkpointThread = null;
         }
@@ -89,6 +93,10 @@
         return asterixAppRuntimeContextProvider;
     }
 
+    public AsterixTransactionProperties getTransactionProperties() {
+        return txnProperties;
+    }
+
     public String getId() {
         return id;
     }
diff --git a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/RecoverySimulator.java b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/RecoverySimulator.java
index 07f7474..862c996 100644
--- a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/RecoverySimulator.java
+++ b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/RecoverySimulator.java
@@ -16,7 +16,10 @@
 
 import java.io.IOException;
 
+import edu.uci.ics.asterix.common.config.AsterixPropertiesAccessor;
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
+import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.IRecoveryManager;
 import edu.uci.ics.asterix.transaction.management.service.transaction.TransactionSubsystem;
 
@@ -28,10 +31,11 @@
         recoveryManager.startRecovery(true);
     }
 
-    public static void main(String args[]) throws IOException, ACIDException {
+    public static void main(String args[]) throws IOException, ACIDException, AsterixException {
         String id = "nc1";
         try {
-            TransactionSubsystem factory = new TransactionSubsystem(id, null);
+            TransactionSubsystem factory = new TransactionSubsystem(id, null, new AsterixTransactionProperties(
+                    new AsterixPropertiesAccessor()));
             IRecoveryManager recoveryManager = factory.getRecoveryManager();
             recoveryManager.startRecovery(true);
         } catch (ACIDException acide) {
diff --git a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/TransactionWorkloadSimulator.java b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/TransactionWorkloadSimulator.java
index 8f56e3b..b9605ef 100644
--- a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/TransactionWorkloadSimulator.java
+++ b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/logging/test/TransactionWorkloadSimulator.java
@@ -18,7 +18,10 @@
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
+import edu.uci.ics.asterix.common.config.AsterixPropertiesAccessor;
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
+import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.DatasetId;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
 import edu.uci.ics.asterix.common.transactions.ILogManager;
@@ -48,8 +51,9 @@
         transactions = new Transaction[workload.numActiveThreads];
     }
 
-    public void beginWorkload() throws ACIDException {
-        provider = new TransactionSubsystem("nc1", null);
+    public void beginWorkload() throws ACIDException, AsterixException {
+        provider = new TransactionSubsystem("nc1", null, new AsterixTransactionProperties(
+                new AsterixPropertiesAccessor()));
         logManager = provider.getLogManager();
         lockManager = provider.getLockManager();
         provider.getTransactionalResourceRepository().registerTransactionalResourceManager(DummyResourceMgr.id,
@@ -83,7 +87,7 @@
         System.out.println(" Avg Content Creation time :" + BasicLogger.getAverageContentCreationTime());
     }
 
-    public static void main(String args[]) {
+    public static void main(String args[]) throws AsterixException {
         WorkloadProperties workload = new WorkloadProperties();
         TransactionWorkloadSimulator simulator = new TransactionWorkloadSimulator(workload);
         try {
@@ -177,12 +181,12 @@
                 byte logActionType = LogActionType.REDO_UNDO;
                 long pageId = 0;
                 if (!retry) {
-                    lockMode = (byte)(random.nextInt(2));
+                    lockMode = (byte) (random.nextInt(2));
                 }
                 tempDatasetId.setId(resourceID);
                 TransactionWorkloadSimulator.lockManager.lock(tempDatasetId, -1, lockMode, context);
-                TransactionWorkloadSimulator.logManager.log(logType, context, resourceID,
-                        -1, resourceID, ResourceType.LSM_BTREE, logSize, null, logger, memLSN);
+                TransactionWorkloadSimulator.logManager.log(logType, context, resourceID, -1, resourceID,
+                        ResourceType.LSM_BTREE, logSize, null, logger, memLSN);
                 retry = false;
                 Thread.currentThread().sleep(TransactionWorkloadSimulator.workload.thinkTime);
                 logCount.incrementAndGet();
diff --git a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/test/TransactionSimulator.java b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/test/TransactionSimulator.java
index 66e9bdf..c322b31 100644
--- a/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/test/TransactionSimulator.java
+++ b/asterix-transactions/src/test/java/edu/uci/ics/asterix/transaction/management/test/TransactionSimulator.java
@@ -17,7 +17,10 @@
 import java.io.IOException;
 import java.util.Random;
 
+import edu.uci.ics.asterix.common.config.AsterixPropertiesAccessor;
+import edu.uci.ics.asterix.common.config.AsterixTransactionProperties;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
+import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.DatasetId;
 import edu.uci.ics.asterix.common.transactions.ILockManager;
 import edu.uci.ics.asterix.common.transactions.ILogManager;
@@ -47,9 +50,10 @@
     private LogicalLogLocator memLSN;
     private TransactionSubsystem transactionProvider;
 
-    public TransactionSimulator(IResource resource, IResourceManager resourceMgr) throws ACIDException {
+    public TransactionSimulator(IResource resource, IResourceManager resourceMgr) throws ACIDException, AsterixException {
         String id = "nc1";
-        transactionProvider = new TransactionSubsystem(id, null);
+        transactionProvider = new TransactionSubsystem(id, null, new AsterixTransactionProperties(
+                new AsterixPropertiesAccessor()));
         transactionManager = transactionProvider.getTransactionManager();
         logManager = transactionProvider.getLogManager();
         lockManager = transactionProvider.getLockManager();
@@ -102,7 +106,7 @@
     /**
      * @param args
      */
-    public static void main(String[] args) throws IOException, ACIDException {
+    public static void main(String[] args) throws IOException, ACIDException, AsterixException {
         String fileDir = "testdata";
         String fileName = "counterFile";
         IResource resource = new FileResource(fileDir, fileName);