diff --git a/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java b/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
index 7d6e96b..ec05b94 100644
--- a/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
+++ b/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
@@ -54,6 +54,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
@@ -517,8 +518,8 @@
         public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
             LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
             lsmHarness.getIOScheduler().scheduleOperation(
-                    new LSMFlushOperation(lsmHarness.getIndex(), componentFileRefs.getInsertIndexFileReference(),
-                            callback));
+                    new LSMFlushOperation((ILSMIndexAccessorInternal) createAccessor(null, null), componentFileRefs
+                            .getInsertIndexFileReference(), callback));
         }
     }
 
@@ -548,8 +549,8 @@
         FileReference lastFile = diskFileMapProvider.lookupFileName(lastBTree.getFileId());
         LSMComponentFileReferences relMergeFileRefs = fileManager.getRelMergeFileReference(firstFile.getFile()
                 .getName(), lastFile.getFile().getName());
-        return new LSMBTreeMergeOperation(lsmHarness.getIndex(), mergingDiskComponents, cursor,
-                relMergeFileRefs.getInsertIndexFileReference(), callback);
+        return new LSMBTreeMergeOperation((ILSMIndexAccessorInternal) createAccessor(null, null),
+                mergingDiskComponents, cursor, relMergeFileRefs.getInsertIndexFileReference(), callback);
     }
 
     @Override
diff --git a/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java b/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
index ec8afaf..a85dbfb 100644
--- a/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
+++ b/hyracks-storage-am-lsm-btree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
@@ -15,33 +15,32 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.btree.impls;
 
-import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 
 public class LSMBTreeMergeOperation implements ILSMIOOperation {
 
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final List<ILSMComponent> mergingComponents;
     private final ITreeIndexCursor cursor;
     private final FileReference mergeTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMBTreeMergeOperation(ILSMIndex index, List<ILSMComponent> mergingComponents, ITreeIndexCursor cursor,
-            FileReference mergeTarget, ILSMIOOperationCallback callback) {
-        this.index = index;
+    public LSMBTreeMergeOperation(ILSMIndexAccessorInternal accessor, List<ILSMComponent> mergingComponents,
+            ITreeIndexCursor cursor, FileReference mergeTarget, ILSMIOOperationCallback callback) {
+        this.accessor = accessor;
         this.mergingComponents = mergingComponents;
         this.cursor = cursor;
         this.mergeTarget = mergeTarget;
@@ -49,8 +48,8 @@
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        List<IODeviceHandle> devs = new ArrayList<IODeviceHandle>();
+    public Set<IODeviceHandle> getReadDevices() {
+        Set<IODeviceHandle> devs = new HashSet<IODeviceHandle>();
         for (ILSMComponent o : mergingComponents) {
             LSMBTreeComponent component = (LSMBTreeComponent) o;
             devs.add(component.getBTree().getFileReference().getDevideHandle());
@@ -59,14 +58,12 @@
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        return Collections.singletonList(mergeTarget.getDevideHandle());
+    public Set<IODeviceHandle> getWriteDevices() {
+        return Collections.singleton(mergeTarget.getDevideHandle());
     }
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.merge(this);
     }
 
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
index 459b0d9..15fdc6e 100644
--- a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
@@ -1,15 +1,15 @@
 package edu.uci.ics.hyracks.storage.am.lsm.common.api;
 
-import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 
 public interface ILSMIOOperation {
-    public List<IODeviceHandle> getReadDevices();
+    public Set<IODeviceHandle> getReadDevices();
 
-    public List<IODeviceHandle> getWriteDevices();
+    public Set<IODeviceHandle> getWriteDevices();
 
     public void perform() throws HyracksDataException, IndexException;
 
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
index 997cc10..8ef03bf 100644
--- a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
@@ -19,7 +19,6 @@
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
 
 /**
  * Client handle for performing operations
@@ -34,22 +33,6 @@
     public void scheduleMerge(ILSMIOOperationCallback callback) throws HyracksDataException, IndexException;
 
     /**
-     * Force a flush of the in-memory component.
-     * 
-     * @throws HyracksDataException
-     * @throws TreeIndexException
-     */
-    public void flush(ILSMIOOperation operation) throws HyracksDataException, IndexException;
-
-    /**
-     * Merge all on-disk components.
-     * 
-     * @throws HyracksDataException
-     * @throws TreeIndexException
-     */
-    public void merge(ILSMIOOperation operation) throws HyracksDataException, IndexException;
-
-    /**
      * Deletes the tuple from the memory component only.
      * 
      * @throws HyracksDataException
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessorInternal.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessorInternal.java
new file mode 100644
index 0000000..8c28d47
--- /dev/null
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/api/ILSMIndexAccessorInternal.java
@@ -0,0 +1,24 @@
+package edu.uci.ics.hyracks.storage.am.lsm.common.api;
+
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
+
+public interface ILSMIndexAccessorInternal extends ILSMIndexAccessor {
+
+    /**
+     * Force a flush of the in-memory component.
+     * 
+     * @throws HyracksDataException
+     * @throws TreeIndexException
+     */
+    public void flush(ILSMIOOperation operation) throws HyracksDataException, IndexException;
+
+    /**
+     * Merge all on-disk components.
+     * 
+     * @throws HyracksDataException
+     * @throws TreeIndexException
+     */
+    public void merge(ILSMIOOperation operation) throws HyracksDataException, IndexException;
+}
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMFlushOperation.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMFlushOperation.java
index 0c70bc1..3046d90 100644
--- a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMFlushOperation.java
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMFlushOperation.java
@@ -1,44 +1,41 @@
 package edu.uci.ics.hyracks.storage.am.lsm.common.impls;
 
 import java.util.Collections;
-import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 
 public class LSMFlushOperation implements ILSMIOOperation {
 
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final FileReference flushTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMFlushOperation(ILSMIndex index, FileReference flushTarget, ILSMIOOperationCallback callback) {
-        this.index = index;
+    public LSMFlushOperation(ILSMIndexAccessorInternal accessor, FileReference flushTarget,
+            ILSMIOOperationCallback callback) {
+        this.accessor = accessor;
         this.flushTarget = flushTarget;
         this.callback = callback;
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        return Collections.emptyList();
+    public Set<IODeviceHandle> getReadDevices() {
+        return Collections.emptySet();
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        return Collections.singletonList(flushTarget.getDevideHandle());
+    public Set<IODeviceHandle> getWriteDevices() {
+        return Collections.singleton(flushTarget.getDevideHandle());
     }
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.flush(this);
     }
 
diff --git a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
index e286a7c..d60c758 100644
--- a/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
+++ b/hyracks-storage-am-lsm-common/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
@@ -24,10 +24,10 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMHarness;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 
-public abstract class LSMTreeIndexAccessor implements ILSMIndexAccessor {
+public abstract class LSMTreeIndexAccessor implements ILSMIndexAccessorInternal {
     protected ILSMHarness lsmHarness;
     protected ILSMIndexOperationContext ctx;
 
diff --git a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
index fd8b7e4..0da39d8 100644
--- a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
+++ b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
@@ -52,6 +52,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMOperationTrackerFactory;
@@ -462,7 +463,8 @@
         String lastFileName = lastInvIndex.getBTree().getFileReference().getFile().getName();
 
         LSMComponentFileReferences relMergeFileRefs = fileManager.getRelMergeFileReference(firstFileName, lastFileName);
-        LSMInvertedIndexMergeOperation mergeOp = new LSMInvertedIndexMergeOperation(this, mergingComponents, cursor,
+        LSMInvertedIndexMergeOperation mergeOp = new LSMInvertedIndexMergeOperation(
+                (ILSMIndexAccessorInternal) createAccessor(null, null), mergingComponents, cursor,
                 relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getDeleteIndexFileReference(),
                 callback);
 
diff --git a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
index 069f10d..7faed0f 100644
--- a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
+++ b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
@@ -24,14 +24,14 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMHarness;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
-import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndexAccessor;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedListCursor;
 
-public class LSMInvertedIndexAccessor implements ILSMIndexAccessor, IInvertedIndexAccessor {
+public class LSMInvertedIndexAccessor implements ILSMIndexAccessorInternal, IInvertedIndexAccessor {
 
     protected final ILSMHarness lsmHarness;
     protected final ILSMIndexFileManager fileManager;
@@ -83,8 +83,9 @@
     public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
         LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
         lsmHarness.getIOScheduler().scheduleOperation(
-                new LSMInvertedIndexFlushOperation(lsmHarness.getIndex(), componentFileRefs
-                        .getInsertIndexFileReference(), componentFileRefs.getDeleteIndexFileReference(), callback));
+                new LSMInvertedIndexFlushOperation((ILSMIndexAccessorInternal) invIndex.createAccessor(null, null),
+                        componentFileRefs.getInsertIndexFileReference(), componentFileRefs
+                                .getDeleteIndexFileReference(), callback));
     }
 
     @Override
diff --git a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
index 3055f52..3379b47 100644
--- a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
+++ b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
@@ -16,46 +16,42 @@
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.impls;
 
 import java.util.Collections;
-import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 
 public class LSMInvertedIndexFlushOperation implements ILSMIOOperation {
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final FileReference dictBTreeFlushTarget;
     private final FileReference deletedKeysBTreeFlushTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMInvertedIndexFlushOperation(ILSMIndex index, FileReference dictBTreeFlushTarget,
+    public LSMInvertedIndexFlushOperation(ILSMIndexAccessorInternal accessor, FileReference dictBTreeFlushTarget,
             FileReference deletedKeysBTreeFlushTarget, ILSMIOOperationCallback callback) {
-        this.index = index;
+        this.accessor = accessor;
         this.dictBTreeFlushTarget = dictBTreeFlushTarget;
         this.deletedKeysBTreeFlushTarget = deletedKeysBTreeFlushTarget;
         this.callback = callback;
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        return Collections.emptyList();
+    public Set<IODeviceHandle> getReadDevices() {
+        return Collections.emptySet();
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        return Collections.singletonList(dictBTreeFlushTarget.getDevideHandle());
+    public Set<IODeviceHandle> getWriteDevices() {
+        return Collections.singleton(dictBTreeFlushTarget.getDevideHandle());
     }
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.flush(this);
     }
 
diff --git a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
index e6baf9d..4289a14 100644
--- a/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
+++ b/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
@@ -15,34 +15,33 @@
 
 package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.impls;
 
-import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.ondisk.OnDiskInvertedIndex;
 
 public class LSMInvertedIndexMergeOperation implements ILSMIOOperation {
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final List<ILSMComponent> mergingComponents;
     private final IIndexCursor cursor;
     private final FileReference dictBTreeMergeTarget;
     private final FileReference deletedKeysBTreeMergeTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMInvertedIndexMergeOperation(ILSMIndex index, List<ILSMComponent> mergingComponents, IIndexCursor cursor,
-            FileReference dictBTreeMergeTarget, FileReference deletedKeysBTreeMergeTarget,
+    public LSMInvertedIndexMergeOperation(ILSMIndexAccessorInternal accessor, List<ILSMComponent> mergingComponents,
+            IIndexCursor cursor, FileReference dictBTreeMergeTarget, FileReference deletedKeysBTreeMergeTarget,
             ILSMIOOperationCallback callback) {
-        this.index = index;
+        this.accessor = accessor;
         this.mergingComponents = mergingComponents;
         this.cursor = cursor;
         this.dictBTreeMergeTarget = dictBTreeMergeTarget;
@@ -51,8 +50,8 @@
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        List<IODeviceHandle> devs = new ArrayList<IODeviceHandle>();
+    public Set<IODeviceHandle> getReadDevices() {
+        Set<IODeviceHandle> devs = new HashSet<IODeviceHandle>();
         for (Object o : mergingComponents) {
             LSMInvertedIndexComponent component = (LSMInvertedIndexComponent) o;
             OnDiskInvertedIndex invIndex = (OnDiskInvertedIndex) component.getInvIndex();
@@ -63,8 +62,8 @@
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        List<IODeviceHandle> devs = new ArrayList<IODeviceHandle>(2);
+    public Set<IODeviceHandle> getWriteDevices() {
+        Set<IODeviceHandle> devs = new HashSet<IODeviceHandle>(2);
         devs.add(dictBTreeMergeTarget.getDevideHandle());
         devs.add(deletedKeysBTreeMergeTarget.getDevideHandle());
         return devs;
@@ -72,8 +71,6 @@
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.merge(this);
     }
 
diff --git a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
index e328634..3e5869c 100644
--- a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
+++ b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
@@ -47,6 +47,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
@@ -329,8 +330,8 @@
             return null;
         }
         LSMComponentFileReferences relMergeFileRefs = getMergeTargetFileName(mergingComponents);
-        return new LSMRTreeMergeOperation(lsmHarness.getIndex(), mergingComponents, cursor,
-                relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getDeleteIndexFileReference(),
+        return new LSMRTreeMergeOperation((ILSMIndexAccessorInternal) createAccessor(null, null), mergingComponents,
+                cursor, relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getDeleteIndexFileReference(),
                 callback);
     }
 
@@ -359,8 +360,9 @@
         public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
             LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
             lsmHarness.getIOScheduler().scheduleOperation(
-                    new LSMRTreeFlushOperation(lsmHarness.getIndex(), componentFileRefs.getInsertIndexFileReference(),
-                            componentFileRefs.getDeleteIndexFileReference(), callback));
+                    new LSMRTreeFlushOperation((ILSMIndexAccessorInternal) createAccessor(null, null),
+                            componentFileRefs.getInsertIndexFileReference(), componentFileRefs
+                                    .getDeleteIndexFileReference(), callback));
         }
     }
 
diff --git a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
index 5ec4776..72cc95a 100644
--- a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
+++ b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
@@ -1,47 +1,47 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
 
 import java.util.Collections;
-import java.util.List;
+import java.util.HashSet;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 
 public class LSMRTreeFlushOperation implements ILSMIOOperation {
 
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final FileReference rtreeFlushTarget;
     private final FileReference btreeFlushTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMRTreeFlushOperation(ILSMIndex index, FileReference rtreeFlushTarget, FileReference btreeFlushTarget,
-            ILSMIOOperationCallback callback) {
-        this.index = index;
+    public LSMRTreeFlushOperation(ILSMIndexAccessorInternal accessor, FileReference rtreeFlushTarget,
+            FileReference btreeFlushTarget, ILSMIOOperationCallback callback) {
+        this.accessor = accessor;
         this.rtreeFlushTarget = rtreeFlushTarget;
         this.btreeFlushTarget = btreeFlushTarget;
         this.callback = callback;
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        return Collections.emptyList();
+    public Set<IODeviceHandle> getReadDevices() {
+        return Collections.emptySet();
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        return Collections.singletonList(rtreeFlushTarget.getDevideHandle());
+    public Set<IODeviceHandle> getWriteDevices() {
+        Set<IODeviceHandle> devs = new HashSet<IODeviceHandle>();
+        devs.add(rtreeFlushTarget.getDevideHandle());
+        devs.add(btreeFlushTarget.getDevideHandle());
+        return devs;
     }
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.flush(this);
     }
 
diff --git a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
index 7449340..7bf4078 100644
--- a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
+++ b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
@@ -1,32 +1,32 @@
 package edu.uci.ics.hyracks.storage.am.lsm.rtree.impls;
 
-import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.api.io.IODeviceHandle;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
-import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 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.ILSMIndexAccessorInternal;
 
 public class LSMRTreeMergeOperation implements ILSMIOOperation {
-    private final ILSMIndex index;
+    private final ILSMIndexAccessorInternal accessor;
     private final List<ILSMComponent> mergingComponents;
     private final ITreeIndexCursor cursor;
     private final FileReference rtreeMergeTarget;
     private final FileReference btreeMergeTarget;
     private final ILSMIOOperationCallback callback;
 
-    public LSMRTreeMergeOperation(ILSMIndex index, List<ILSMComponent> mergingComponents, ITreeIndexCursor cursor,
-            FileReference rtreeMergeTarget, FileReference btreeMergeTarget, ILSMIOOperationCallback callback) {
-        this.index = index;
+    public LSMRTreeMergeOperation(ILSMIndexAccessorInternal accessor, List<ILSMComponent> mergingComponents,
+            ITreeIndexCursor cursor, FileReference rtreeMergeTarget, FileReference btreeMergeTarget,
+            ILSMIOOperationCallback callback) {
+        this.accessor = accessor;
         this.mergingComponents = mergingComponents;
         this.cursor = cursor;
         this.rtreeMergeTarget = rtreeMergeTarget;
@@ -35,24 +35,23 @@
     }
 
     @Override
-    public List<IODeviceHandle> getReadDevices() {
-        List<IODeviceHandle> devs = new ArrayList<IODeviceHandle>();
+    public Set<IODeviceHandle> getReadDevices() {
+        Set<IODeviceHandle> devs = new HashSet<IODeviceHandle>();
         for (ILSMComponent o : mergingComponents) {
             LSMRTreeComponent component = (LSMRTreeComponent) o;
             devs.add(component.getRTree().getFileReference().getDevideHandle());
+            devs.add(component.getBTree().getFileReference().getDevideHandle());
         }
         return devs;
     }
 
     @Override
-    public List<IODeviceHandle> getWriteDevices() {
-        return Collections.singletonList(rtreeMergeTarget.getDevideHandle());
+    public Set<IODeviceHandle> getWriteDevices() {
+        return Collections.singleton(rtreeMergeTarget.getDevideHandle());
     }
 
     @Override
     public void perform() throws HyracksDataException, IndexException {
-        ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
-                NoOpOperationCallback.INSTANCE);
         accessor.merge(this);
     }
 
diff --git a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
index 3441bd3..703cd21 100644
--- a/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
+++ b/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
@@ -48,6 +48,7 @@
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIOOperationScheduler;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessorInternal;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexFileManager;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
@@ -336,7 +337,7 @@
         public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
             LSMComponentFileReferences relFlushFileRefs = fileManager.getRelFlushFileReference();
             lsmHarness.getIOScheduler().scheduleOperation(
-                    new LSMFlushOperation(lsmHarness.getIndex(), relFlushFileRefs.getInsertIndexFileReference(),
+                    new LSMFlushOperation((ILSMIndexAccessorInternal) createAccessor(null, null), relFlushFileRefs.getInsertIndexFileReference(),
                             callback));
         }
     }
@@ -418,8 +419,8 @@
         }
 
         LSMComponentFileReferences relMergeFileRefs = getMergeTargetFileName(mergingComponents);
-        return new LSMRTreeMergeOperation(lsmHarness.getIndex(), mergingComponents, cursor,
-                relMergeFileRefs.getInsertIndexFileReference(), null, callback);
+        return new LSMRTreeMergeOperation((ILSMIndexAccessorInternal) createAccessor(null, null), mergingComponents,
+                cursor, relMergeFileRefs.getInsertIndexFileReference(), null, callback);
     }
 
     @Override