diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixAppRuntimeContext.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixAppRuntimeContext.java
index d25f9cc..b77fc99 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixAppRuntimeContext.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixAppRuntimeContext.java
@@ -13,11 +13,11 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMFlushController;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTrackerFactory;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.ConstantMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.FlushController;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.ImmediateScheduler;
-import edu.uci.ics.hyracks.storage.am.lsm.common.impls.ReferenceCountingOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.RefCountingOperationTrackerFactory;
 import edu.uci.ics.hyracks.storage.common.buffercache.BufferCache;
 import edu.uci.ics.hyracks.storage.common.buffercache.ClockPageReplacementStrategy;
 import edu.uci.ics.hyracks.storage.common.buffercache.HeapBufferAllocator;
@@ -44,7 +44,7 @@
 
     private ILSMFlushController flushController;
     private ILSMMergePolicy mergePolicy;
-    private ILSMOperationTracker opTracker;
+    private ILSMOperationTrackerFactory opTrackerFactory;
     private ILSMIOOperationScheduler lsmIOScheduler;
     private ILocalResourceRepository localResourceRepository;
     private ResourceIdFactory resourceIdFactory;
@@ -68,7 +68,7 @@
         flushController = new FlushController();
         lsmIOScheduler = ImmediateScheduler.INSTANCE;
         mergePolicy = new ConstantMergePolicy(lsmIOScheduler, 3);
-        opTracker = new ReferenceCountingOperationTracker();
+        opTrackerFactory = RefCountingOperationTrackerFactory.INSTANCE;
 
         ILocalResourceRepositoryFactory persistentLocalResourceRepositoryFactory = new PersistentLocalResourceRepositoryFactory(
                 ioMgr);
@@ -147,8 +147,8 @@
         return mergePolicy;
     }
 
-    public ILSMOperationTracker getLSMOperationTracker() {
-        return opTracker;
+    public ILSMOperationTrackerFactory getLSMOperationTrackerFactory() {
+        return opTrackerFactory;
     }
 
     public ILSMIOOperationScheduler getLSMIOScheduler() {
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixRuntimeComponentsProvider.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixRuntimeComponentsProvider.java
index 49f59a0..a5684fc 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixRuntimeComponentsProvider.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/AsterixRuntimeComponentsProvider.java
@@ -7,10 +7,12 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMFlushControllerProvider;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationSchedulerProvider;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndex;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicyProvider;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTrackerProvider;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTrackerFactory;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.ReferenceCountingOperationTracker;
 import edu.uci.ics.hyracks.storage.common.IStorageManagerInterface;
 import edu.uci.ics.hyracks.storage.common.buffercache.IBufferCache;
 import edu.uci.ics.hyracks.storage.common.file.IFileMapProvider;
@@ -18,16 +20,15 @@
 import edu.uci.ics.hyracks.storage.common.file.ResourceIdFactory;
 
 public enum AsterixRuntimeComponentsProvider implements IIndexLifecycleManagerProvider, IStorageManagerInterface,
-        ILSMIOOperationSchedulerProvider, ILSMFlushControllerProvider, ILSMOperationTrackerProvider,
-        ILSMMergePolicyProvider {
+        ILSMIOOperationSchedulerProvider, ILSMFlushControllerProvider, ILSMMergePolicyProvider, ILSMOperationTrackerFactory {
     INSTANCE;
 
     @Override
-    public ILSMOperationTracker getOperationTracker(IHyracksTaskContext ctx) {
-        return ((AsterixAppRuntimeContext) ctx.getJobletContext().getApplicationContext().getApplicationObject())
-                .getLSMOperationTracker();
+    public ILSMOperationTracker createOperationTracker(ILSMIndex index) {
+        // TODO: Replace this with the IndexOperationTracker, once the other transactional components are in place.
+        return new ReferenceCountingOperationTracker(index);
     }
-
+    
     @Override
     public ILSMFlushController getFlushController(IHyracksTaskContext ctx) {
         return ((AsterixAppRuntimeContext) ctx.getJobletContext().getApplicationContext().getApplicationObject())
diff --git a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
index 301c335..7342a85 100644
--- a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
+++ b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
@@ -75,10 +75,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
-import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
-import edu.uci.ics.hyracks.storage.am.lsm.btree.impls.LSMBTreeRangeSearchCursor;
-import edu.uci.ics.hyracks.storage.am.lsm.btree.tuples.LSMBTreeTupleReference;
 
 public class MetadataNode implements IMetadataNode {
     private static final long serialVersionUID = 1L;
@@ -787,7 +784,7 @@
         indexLifecycleManager.open(resourceID);
         IIndexAccessor indexAccessor = indexInstance.createAccessor(NoOpOperationCallback.INSTANCE,
                 NoOpOperationCallback.INSTANCE);
-        ITreeIndexCursor rangeCursor = new LSMBTreeRangeSearchCursor();
+        ITreeIndexCursor rangeCursor = (ITreeIndexCursor) indexAccessor.createSearchCursor();
         IBinaryComparator[] searchCmps = new IBinaryComparator[searchKey.getFieldCount()];
         for (int i = 0; i < searchKey.getFieldCount(); i++) {
             searchCmps[i] = comparatorFactories[i].createBinaryComparator();
diff --git a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/bootstrap/MetadataBootstrap.java b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/bootstrap/MetadataBootstrap.java
index 91e734d..26148bb 100644
--- a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/bootstrap/MetadataBootstrap.java
+++ b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/bootstrap/MetadataBootstrap.java
@@ -301,7 +301,7 @@
                 metaDataFrameFactory);
         LSMBTree lsmBtree = LSMBTreeUtils.createLSMTree(memBufferCache, memFreePageManager, ioManager, file,
                 bufferCache, fileMapProvider, typeTraits, comparatorFactories, runtimeContext.getFlushController(),
-                runtimeContext.getLSMMergePolicy(), runtimeContext.getLSMOperationTracker(),
+                runtimeContext.getLSMMergePolicy(), runtimeContext.getLSMOperationTrackerFactory(),
                 runtimeContext.getLSMIOScheduler());
         long resourceID = -1;
         if (create) {
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallback.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallback.java
index 58dd2d0..a907ee3 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallback.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallback.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -27,7 +27,8 @@
     protected final IBinaryHashFunction[] primaryKeyHashFunctions;
     protected final ILockManager lockManager;
     protected final TransactionContext txnCtx;
-
+    protected int transactorLocalNumActiveOperations = 0;
+    
     public AbstractOperationCallback(DatasetId datasetId, int[] primaryKeyFields,
             IBinaryHashFunction[] primaryKeyHashFunctions, TransactionContext txnCtx, ILockManager lockManager) {
         this.datasetId = datasetId;
@@ -41,11 +42,27 @@
             IBinaryHashFunction[] primaryKeyHashFunctions) {
         int h = 0;
         for (int i = 0; i < primaryKeyFields.length; i++) {
-            int entityFieldIdx = primaryKeyFields[i];
-            int fh = primaryKeyHashFunctions[i].hash(tuple.getFieldData(entityFieldIdx),
-                    tuple.getFieldStart(entityFieldIdx), tuple.getFieldLength(entityFieldIdx));
+            int primaryKeyFieldIdx = primaryKeyFields[i];
+            int fh = primaryKeyHashFunctions[i].hash(tuple.getFieldData(primaryKeyFieldIdx),
+                    tuple.getFieldStart(primaryKeyFieldIdx), tuple.getFieldLength(primaryKeyFieldIdx));
             h = h * 31 + fh;
         }
         return h;
     }
+    
+    public TransactionContext getTransactionContext() {
+        return txnCtx;
+    }
+    
+    public int getLocalNumActiveOperations() {
+        return transactorLocalNumActiveOperations;
+    }
+    
+    public void incrementLocalNumActiveOperations() {
+        transactorLocalNumActiveOperations++;
+    }
+    
+    public void decrementLocalNumActiveOperations() {
+        transactorLocalNumActiveOperations--;
+    }
 }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallbackFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallbackFactory.java
index ea82ba7..8d11d04 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallbackFactory.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/AbstractOperationCallbackFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTracker.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTracker.java
new file mode 100644
index 0000000..1635191
--- /dev/null
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTracker.java
@@ -0,0 +1,99 @@
+/*
+ * 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.asterix.transaction.management.opcallbacks;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
+import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndex;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+
+public class IndexOperationTracker implements ILSMOperationTracker {
+
+    // Number of active operations on a ILSMIndex instance.
+    private int numActiveOperations = 0;
+    private final ILSMIndex index;
+    private final ILSMIndexAccessor accessor;    
+    private final FlushOperationCallback FLUSHCALLBACK_INSTANCE = new FlushOperationCallback();
+    
+    public IndexOperationTracker(ILSMIndex index) {
+        this.index = index;
+        accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
+                NoOpOperationCallback.INSTANCE);
+    }     
+
+    @Override
+    public synchronized void beforeOperation(ILSMIndexOperationContext opCtx) throws HyracksDataException {
+        // Wait for pending flushes to complete.
+        // If flushFlag is set, then the flush is queued to occur by the last completing operation.
+        // This operation should wait for that flush to occur before proceeding.
+        if (index.getFlushController().getFlushStatus(index)) {
+            try {
+                this.wait();
+            } catch (InterruptedException e) {
+                throw new HyracksDataException(e);
+            }
+        }
+        numActiveOperations++;
+        
+        // Increment transactor-local active operations count.
+        AbstractOperationCallback opCallback = getOperationCallback(opCtx);
+        opCallback.incrementLocalNumActiveOperations();
+    }
+
+    @Override
+    public void afterOperation(ILSMIndexOperationContext opCtx) throws HyracksDataException {
+        // Searches are immediately considered complete, because they should not prevent the execution of flushes.
+        IndexOperation op = opCtx.getOperation();
+        if (op == IndexOperation.SEARCH || op == IndexOperation.DISKORDERSCAN) {
+            completeOperation(opCtx);
+        }
+    }
+
+    @Override
+    public synchronized void completeOperation(ILSMIndexOperationContext opCtx) throws HyracksDataException {
+        numActiveOperations--;
+
+        // Decrement transactor-local active operations count.
+        AbstractOperationCallback opCallback = getOperationCallback(opCtx);
+        opCallback.decrementLocalNumActiveOperations();
+        
+        // If we need a flush, and this is the last completing operation, then schedule the flush.
+        // Once the flush has completed notify all waiting operations.
+        if (index.getFlushController().getFlushStatus(index) && numActiveOperations == 0) {
+            index.getIOScheduler().scheduleOperation(accessor.createFlushOperation(FLUSHCALLBACK_INSTANCE));
+        }
+    }
+    
+    private AbstractOperationCallback getOperationCallback(ILSMIndexOperationContext opCtx) {
+        IndexOperation op = opCtx.getOperation();
+        if (op == IndexOperation.SEARCH || op == IndexOperation.DISKORDERSCAN) {
+            return (AbstractOperationCallback) opCtx.getSearchOperationCallback();
+        } else {
+            return (AbstractOperationCallback) opCtx.getModificationCallback();
+        }
+    }
+    
+    private class FlushOperationCallback implements ILSMIOOperationCallback {        
+        @Override
+        public void callback() {
+            IndexOperationTracker.this.notifyAll();
+        }
+    }
+}
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTrackerFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTrackerFactory.java
new file mode 100644
index 0000000..1cbc110
--- /dev/null
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/IndexOperationTrackerFactory.java
@@ -0,0 +1,31 @@
+/*
+ * 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.asterix.transaction.management.opcallbacks;
+
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndex;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTracker;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTrackerFactory;
+
+public class IndexOperationTrackerFactory implements ILSMOperationTrackerFactory {
+
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public ILSMOperationTracker createOperationTracker(ILSMIndex index) {
+        return new IndexOperationTracker(index);
+    }
+
+}
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallback.java
similarity index 88%
rename from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java
rename to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallback.java
index 6e17f3f..3c9f092 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallback.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -30,14 +30,18 @@
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.btree.tuples.LSMBTreeTupleReference;
 
-public class LSMBTreeModificationOperationCallback extends AbstractOperationCallback implements
+/**
+ * Assumes LSM-BTrees as primary indexes.
+ * Performs locking on primary keys, and also logs before/after images.
+ */
+public class PrimaryIndexModificationOperationCallback extends AbstractOperationCallback implements
         IModificationOperationCallback {
 
     protected final long resourceId;
     protected final IndexOperation indexOp;
     protected final TransactionSubsystem txnSubsystem;
-    
-    public LSMBTreeModificationOperationCallback(DatasetId datasetId, int[] primaryKeyFields,
+
+    public PrimaryIndexModificationOperationCallback(DatasetId datasetId, int[] primaryKeyFields,
             IBinaryHashFunction[] primaryKeyHashFunctions, TransactionContext txnCtx, ILockManager lockManager,
             TransactionSubsystem txnSubsystem, long resourceId, IndexOperation indexOp) {
         super(datasetId, primaryKeyFields, primaryKeyHashFunctions, txnCtx, lockManager);
@@ -66,7 +70,8 @@
             oldOp = IndexOperation.DELETE;
         }
         try {
-            logger.generateLogRecord(txnSubsystem, txnCtx, datasetId.getId(), pkHash, resourceId, indexOp, after, oldOp, before);
+            logger.generateLogRecord(txnSubsystem, txnCtx, datasetId.getId(), pkHash, resourceId, indexOp, after,
+                    oldOp, before);
         } catch (ACIDException e) {
             throw new HyracksDataException(e);
         }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallbackFactory.java
similarity index 84%
rename from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java
rename to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallbackFactory.java
index 92f669c..2309724 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexModificationOperationCallbackFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -28,13 +28,16 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallbackFactory;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 
-public class LSMBTreeModificationOperationCallbackFactory extends AbstractOperationCallbackFactory implements
+/**
+ * Assumes LSM-BTrees as primary indexes.
+ */
+public class PrimaryIndexModificationOperationCallbackFactory extends AbstractOperationCallbackFactory implements
         IModificationOperationCallbackFactory {
 
     private static final long serialVersionUID = 1L;
     private final IndexOperation indexOp;
 
-    public LSMBTreeModificationOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] primaryKeyFields,
+    public PrimaryIndexModificationOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] primaryKeyFields,
             IBinaryHashFunction[] primaryKeyHashFunctions, ITransactionSubsystemProvider txnSubsystemProvider,
             IndexOperation indexOp) {
         super(jobId, datasetId, primaryKeyFields, primaryKeyHashFunctions, txnSubsystemProvider);
@@ -47,11 +50,10 @@
         TransactionSubsystem txnSubsystem = txnSubsystemProvider.getTransactionSubsystem(ctx);
         try {
             TransactionContext txnCtx = txnSubsystem.getTransactionManager().getTransactionContext(jobId);
-            return new LSMBTreeModificationOperationCallback(datasetId, primaryKeyFields, primaryKeyHashFunctions,
+            return new PrimaryIndexModificationOperationCallback(datasetId, primaryKeyFields, primaryKeyHashFunctions,
                     txnCtx, txnSubsystem.getLockManager(), txnSubsystem, resourceId, indexOp);
         } catch (ACIDException e) {
             throw new HyracksDataException(e);
         }
     }
-
 }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallback.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallback.java
similarity index 87%
rename from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallback.java
rename to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallback.java
index bebe823..d055126 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallback.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallback.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -25,9 +25,12 @@
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 
-public class SearchOperationCallback extends AbstractOperationCallback implements ISearchOperationCallback {
+/**
+ * Assumes LSM-BTrees as primary indexes. Implements try/locking and unlocking on primary keys.
+ */
+public class PrimaryIndexSearchOperationCallback extends AbstractOperationCallback implements ISearchOperationCallback {
 
-    public SearchOperationCallback(DatasetId datasetId, int[] entityIdFields,
+    public PrimaryIndexSearchOperationCallback(DatasetId datasetId, int[] entityIdFields,
             IBinaryHashFunction[] entityIdFieldHashFunctions, ILockManager lockManager, TransactionContext txnCtx) {
         super(datasetId, entityIdFields, entityIdFieldHashFunctions, txnCtx, lockManager);
     }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallbackFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallbackFactory.java
similarity index 85%
rename from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallbackFactory.java
rename to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallbackFactory.java
index 1cd6444..a124196 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SearchOperationCallbackFactory.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/PrimaryIndexSearchOperationCallbackFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -27,12 +27,12 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallbackFactory;
 
-public class SearchOperationCallbackFactory extends AbstractOperationCallbackFactory implements
+public class PrimaryIndexSearchOperationCallbackFactory extends AbstractOperationCallbackFactory implements
         ISearchOperationCallbackFactory {
 
     private static final long serialVersionUID = 1L;
 
-    public SearchOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] entityIdFields,
+    public PrimaryIndexSearchOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] entityIdFields,
             IBinaryHashFunction[] entityIdFieldHashFunctions, ITransactionSubsystemProvider txnSubsystemProvider) {
         super(jobId, datasetId, entityIdFields, entityIdFieldHashFunctions, txnSubsystemProvider);
     }
@@ -43,7 +43,7 @@
         TransactionSubsystem txnSubsystem = txnSubsystemProvider.getTransactionSubsystem(ctx);
         try {
             TransactionContext txnCtx = txnSubsystem.getTransactionManager().getTransactionContext(jobId);
-            return new SearchOperationCallback(datasetId, primaryKeyFields, primaryKeyHashFunctions,
+            return new PrimaryIndexSearchOperationCallback(datasetId, primaryKeyFields, primaryKeyHashFunctions,
                     txnSubsystem.getLockManager(), txnCtx);
         } catch (ACIDException e) {
             throw new HyracksDataException(e);
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallback.java
similarity index 72%
copy from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java
copy to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallback.java
index 6e17f3f..d2fa889 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallback.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallback.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -21,52 +21,48 @@
 import edu.uci.ics.asterix.transaction.management.service.transaction.DatasetId;
 import edu.uci.ics.asterix.transaction.management.service.transaction.IResourceManager.ResourceType;
 import edu.uci.ics.asterix.transaction.management.service.transaction.TransactionContext;
-import edu.uci.ics.asterix.transaction.management.service.transaction.TransactionManagementConstants.LockManagerConstants.LockMode;
 import edu.uci.ics.asterix.transaction.management.service.transaction.TransactionSubsystem;
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunction;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
-import edu.uci.ics.hyracks.storage.am.lsm.btree.tuples.LSMBTreeTupleReference;
 
-public class LSMBTreeModificationOperationCallback extends AbstractOperationCallback implements
+/**
+ * Secondary-index modifications do not require any locking.
+ * We assume that the modification of the corresponding primary index has already taken an appropriate lock.
+ * This callback performs logging of the before and/or after images for secondary indexes.
+ */
+public class SecondaryIndexModificationOperationCallback extends AbstractOperationCallback implements
         IModificationOperationCallback {
 
     protected final long resourceId;
     protected final IndexOperation indexOp;
+    protected final IndexOperation oldOp;
     protected final TransactionSubsystem txnSubsystem;
-    
-    public LSMBTreeModificationOperationCallback(DatasetId datasetId, int[] primaryKeyFields,
+
+    public SecondaryIndexModificationOperationCallback(DatasetId datasetId, int[] primaryKeyFields,
             IBinaryHashFunction[] primaryKeyHashFunctions, TransactionContext txnCtx, ILockManager lockManager,
             TransactionSubsystem txnSubsystem, long resourceId, IndexOperation indexOp) {
         super(datasetId, primaryKeyFields, primaryKeyHashFunctions, txnCtx, lockManager);
         this.resourceId = resourceId;
         this.indexOp = indexOp;
+        oldOp = (indexOp == IndexOperation.DELETE) ? IndexOperation.INSERT : IndexOperation.DELETE;
         this.txnSubsystem = txnSubsystem;
     }
 
     @Override
     public void before(ITupleReference tuple) throws HyracksDataException {
-        int pkHash = computePrimaryKeyHashValue(tuple, primaryKeyFields, primaryKeyHashFunctions);
-        try {
-            lockManager.lock(datasetId, pkHash, LockMode.X, txnCtx);
-        } catch (ACIDException e) {
-            throw new HyracksDataException(e);
-        }
+        // Do nothing.
     }
 
     @Override
     public void found(ITupleReference before, ITupleReference after) throws HyracksDataException {
         IndexLogger logger = txnSubsystem.getTreeLoggerRepository().getIndexLogger(resourceId, ResourceType.LSM_BTREE);
         int pkHash = computePrimaryKeyHashValue(after, primaryKeyFields, primaryKeyHashFunctions);
-        LSMBTreeTupleReference lsmBTreeTuple = (LSMBTreeTupleReference) before;
-        IndexOperation oldOp = IndexOperation.INSERT;
-        if (lsmBTreeTuple.isAntimatter()) {
-            oldOp = IndexOperation.DELETE;
-        }
         try {
-            logger.generateLogRecord(txnSubsystem, txnCtx, datasetId.getId(), pkHash, resourceId, indexOp, after, oldOp, before);
+            logger.generateLogRecord(txnSubsystem, txnCtx, datasetId.getId(), pkHash, resourceId, indexOp, after,
+                    oldOp, before);
         } catch (ACIDException e) {
             throw new HyracksDataException(e);
         }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallbackFactory.java
similarity index 82%
copy from asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java
copy to asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallbackFactory.java
index 92f669c..51ea0bf 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/LSMBTreeModificationOperationCallbackFactory.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexModificationOperationCallbackFactory.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2009-2010 by The Regents of the University of California
+ * 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
@@ -28,13 +28,13 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallbackFactory;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 
-public class LSMBTreeModificationOperationCallbackFactory extends AbstractOperationCallbackFactory implements
+public class SecondaryIndexModificationOperationCallbackFactory extends AbstractOperationCallbackFactory implements
         IModificationOperationCallbackFactory {
 
     private static final long serialVersionUID = 1L;
     private final IndexOperation indexOp;
 
-    public LSMBTreeModificationOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] primaryKeyFields,
+    public SecondaryIndexModificationOperationCallbackFactory(JobId jobId, DatasetId datasetId, int[] primaryKeyFields,
             IBinaryHashFunction[] primaryKeyHashFunctions, ITransactionSubsystemProvider txnSubsystemProvider,
             IndexOperation indexOp) {
         super(jobId, datasetId, primaryKeyFields, primaryKeyHashFunctions, txnSubsystemProvider);
@@ -47,11 +47,10 @@
         TransactionSubsystem txnSubsystem = txnSubsystemProvider.getTransactionSubsystem(ctx);
         try {
             TransactionContext txnCtx = txnSubsystem.getTransactionManager().getTransactionContext(jobId);
-            return new LSMBTreeModificationOperationCallback(datasetId, primaryKeyFields, primaryKeyHashFunctions,
-                    txnCtx, txnSubsystem.getLockManager(), txnSubsystem, resourceId, indexOp);
+            return new SecondaryIndexModificationOperationCallback(datasetId, primaryKeyFields,
+                    primaryKeyHashFunctions, txnCtx, txnSubsystem.getLockManager(), txnSubsystem, resourceId, indexOp);
         } catch (ACIDException e) {
             throw new HyracksDataException(e);
         }
     }
-
 }
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallback.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallback.java
new file mode 100644
index 0000000..67c9ba0
--- /dev/null
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallback.java
@@ -0,0 +1,47 @@
+/*
+ * 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.asterix.transaction.management.opcallbacks;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
+import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
+
+/**
+ * Secondary index searches perform no locking at all.
+ */
+public class SecondaryIndexSearchOperationCallback extends AbstractOperationCallback implements
+        ISearchOperationCallback {
+
+    public SecondaryIndexSearchOperationCallback() {
+        super(null, null, null, null, null);
+    }
+
+    @Override
+    public boolean proceed(ITupleReference tuple) throws HyracksDataException {
+        return true;
+    }
+
+    @Override
+    public void reconcile(ITupleReference tuple) throws HyracksDataException {
+        // Do nothing.
+    }
+
+    @Override
+    public void cancel(ITupleReference tuple) throws HyracksDataException {
+        // Do nothing.
+    }
+
+}
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallbackFactory.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallbackFactory.java
new file mode 100644
index 0000000..7172e06
--- /dev/null
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/opcallbacks/SecondaryIndexSearchOperationCallbackFactory.java
@@ -0,0 +1,32 @@
+/*
+ * 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.asterix.transaction.management.opcallbacks;
+
+import edu.uci.ics.hyracks.api.context.IHyracksTaskContext;
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
+import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallbackFactory;
+
+public class SecondaryIndexSearchOperationCallbackFactory implements ISearchOperationCallbackFactory {
+
+    private static final long serialVersionUID = 1L;
+
+    @Override
+    public ISearchOperationCallback createSearchOperationCallback(long resourceId, IHyracksTaskContext ctx)
+            throws HyracksDataException {
+        return new SecondaryIndexSearchOperationCallback();
+    }
+}
diff --git a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionContext.java b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionContext.java
index 8c93477..d3b3b36 100644
--- a/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionContext.java
+++ b/asterix-transactions/src/main/java/edu/uci/ics/asterix/transaction/management/service/transaction/TransactionContext.java
@@ -44,7 +44,7 @@
     }
 
     private static final long serialVersionUID = -6105616785783310111L;
-    private TransactionSubsystem transactionProvider;
+    private TransactionSubsystem transactionSubsystem;
     private LogicalLogLocator lastLogLocator;
     private TransactionState txnState;
     private long startWaitTime;
@@ -67,12 +67,12 @@
 
     public TransactionContext(JobId jobId, TransactionSubsystem transactionProvider) throws ACIDException {
         this.jobId = jobId;
-        this.transactionProvider = transactionProvider;
+        this.transactionSubsystem = transactionProvider;
         init();
     }
 
     private void init() throws ACIDException {
-        lastLogLocator = LogUtil.getDummyLogicalLogLocator(transactionProvider.getLogManager());
+        lastLogLocator = LogUtil.getDummyLogicalLogLocator(transactionSubsystem.getLogManager());
         txnState = TransactionState.ACTIVE;
         startWaitTime = INVALID_TIME;
         status = ACTIVE_STATUS;