diff --git a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/ComponentRollbackTest.java b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/ComponentRollbackTest.java
index 76bec8c..5e0e072 100644
--- a/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/ComponentRollbackTest.java
+++ b/asterixdb/asterix-app/src/test/java/org/apache/asterix/test/dataflow/ComponentRollbackTest.java
@@ -132,9 +132,9 @@
     public void createIndex() throws Exception {
         List<List<String>> partitioningKeys = new ArrayList<>();
         partitioningKeys.add(Collections.singletonList("key"));
-        dataset = new TestDataset(DATAVERSE_NAME, DATASET_NAME, DATAVERSE_NAME, DATA_TYPE_NAME,
-                NODE_GROUP_NAME, null, null, new InternalDatasetDetails(null, PartitioningStrategy.HASH,
-                        partitioningKeys, null, null, null, false, null, false),
+        dataset = new TestDataset(DATAVERSE_NAME, DATASET_NAME, DATAVERSE_NAME, DATA_TYPE_NAME, NODE_GROUP_NAME, null,
+                null, new InternalDatasetDetails(null, PartitioningStrategy.HASH, partitioningKeys, null, null, null,
+                        false, null, false),
                 null, DatasetType.INTERNAL, DATASET_ID, 0);
         PrimaryIndexInfo primaryIndexInfo = nc.createPrimaryIndex(dataset, KEY_TYPES, RECORD_TYPE, META_TYPE,
                 new NoMergePolicyFactory(), null, null, storageManager, KEY_INDEXES, KEY_INDICATORS_LIST);
@@ -448,7 +448,7 @@
             for (int i = 0; i < numMergedComponents; i++) {
                 mergedComponents.add(diskComponents.get(i));
             }
-            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents);
+            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents, null);
             merger.waitUntilCount(1);
             // now that we enetered, we will rollback
             Rollerback rollerback = new Rollerback(lsmBtree, new DiskComponentLsnPredicate(lsn));
@@ -635,7 +635,7 @@
             for (int i = 0; i < numMergedComponents; i++) {
                 mergedComponents.add(diskComponents.get(i));
             }
-            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents);
+            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents, null);
             merger.waitUntilCount(1);
             // we will block search
             lsmBtree.clearSearchCallbacks();
@@ -707,7 +707,7 @@
             for (int i = 0; i < numMergedComponents; i++) {
                 mergedComponents.add(diskComponents.get(i));
             }
-            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents);
+            mergeAccessor.scheduleMerge(lsmBtree.getIOOperationCallback(), mergedComponents, null);
             merger.waitUntilCount(1);
             // we will block search
             lsmBtree.clearSearchCallbacks();
@@ -736,7 +736,7 @@
     }
 
     private class Rollerback {
-        private Thread task;
+        private final Thread task;
         private Exception failure;
 
         public Rollerback(TestLsmBtree lsmBtree, Predicate<ILSMComponent> predicate) {
@@ -766,7 +766,7 @@
     }
 
     private class Searcher {
-        private ExecutorService executor = Executors.newSingleThreadExecutor();
+        private final ExecutorService executor = Executors.newSingleThreadExecutor();
         private Future<Boolean> task;
         private volatile boolean entered = false;
 
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/CorrelatedPrefixMergePolicy.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/CorrelatedPrefixMergePolicy.java
index a20e660..e18181c 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/CorrelatedPrefixMergePolicy.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/CorrelatedPrefixMergePolicy.java
@@ -31,6 +31,7 @@
 import org.apache.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMDiskComponent;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMDiskComponentId;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndex;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.PrefixMergePolicy;
@@ -91,14 +92,17 @@
 
         Set<IndexInfo> indexInfos = datasetLifecycleManager.getDatasetInfo(datasetId).getDatsetIndexInfos();
         int partition = getIndexPartition(index, indexInfos);
-        triggerScheduledMerge(minID, maxID,
+        List<ILSMIOOperation> dependingMerges = scheduleSecondaryIndexes(minID, maxID,
                 indexInfos.stream().filter(info -> info.getPartition() == partition).collect(Collectors.toSet()));
+
+        schedulePrimaryIndex(minID, maxID, index, dependingMerges);
+
         return true;
     }
 
     /**
      * Submit merge requests for all disk components within [minID, maxID]
-     * of all indexes of a given dataset in the given partition
+     * of all of secondary indexes of a given dataset in the given partition
      *
      * @param minID
      * @param maxID
@@ -106,17 +110,39 @@
      * @param indexInfos
      * @throws HyracksDataException
      */
-    private void triggerScheduledMerge(long minID, long maxID, Set<IndexInfo> indexInfos) throws HyracksDataException {
+    private List<ILSMIOOperation> scheduleSecondaryIndexes(long minID, long maxID, Set<IndexInfo> indexInfos)
+            throws HyracksDataException {
+        List<ILSMIOOperation> mergeOps = new ArrayList<>();
         for (IndexInfo info : indexInfos) {
             ILSMIndex lsmIndex = info.getIndex();
-
-            List<ILSMDiskComponent> immutableComponents = new ArrayList<>(lsmIndex.getDiskComponents());
-            if (isMergeOngoing(immutableComponents)) {
+            List<ILSMDiskComponent> diskComponents = lsmIndex.getDiskComponents();
+            if (lsmIndex.isPrimaryIndex() || isMergeOngoing(diskComponents)) {
                 continue;
             }
-            List<ILSMDiskComponent> mergableComponents = new ArrayList<>();
-            for (ILSMDiskComponent component : immutableComponents) {
-                ILSMDiskComponentId id = component.getComponentId();
+            List<ILSMDiskComponent> mergeableComponents = collectMergeableComponents(minID, maxID, diskComponents);
+            ILSMIndexAccessor accessor =
+                    lsmIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            mergeOps.add(accessor.scheduleMerge(lsmIndex.getIOOperationCallback(), mergeableComponents, null));
+        }
+        return mergeOps;
+    }
+
+    private void schedulePrimaryIndex(long minID, long maxID, ILSMIndex primaryIndex,
+            List<ILSMIOOperation> dependingMerges) throws HyracksDataException {
+        assert primaryIndex.isPrimaryIndex();
+        List<ILSMDiskComponent> diskComponents = primaryIndex.getDiskComponents();
+        List<ILSMDiskComponent> mergeableComponents = collectMergeableComponents(minID, maxID, diskComponents);
+        ILSMIndexAccessor accessor =
+                primaryIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+        accessor.scheduleMerge(primaryIndex.getIOOperationCallback(), mergeableComponents, dependingMerges);
+    }
+
+    private List<ILSMDiskComponent> collectMergeableComponents(long minID, long maxID,
+            List<ILSMDiskComponent> diskComponents) throws HyracksDataException {
+        List<ILSMDiskComponent> mergableComponents = new ArrayList<>();
+        for (ILSMDiskComponent component : diskComponents) {
+            ILSMDiskComponentId id = component.getComponentId();
+            if (!id.notFound()) {
                 if (id.getMinId() >= minID && id.getMaxId() <= maxID) {
                     mergableComponents.add(component);
                 }
@@ -126,10 +152,8 @@
                     break;
                 }
             }
-            ILSMIndexAccessor accessor =
-                    lsmIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            accessor.scheduleMerge(lsmIndex.getIOOperationCallback(), mergableComponents);
         }
+        return mergableComponents;
     }
 
     private int getIndexPartition(ILSMIndex index, Set<IndexInfo> indexInfos) {
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetInfo.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetInfo.java
index 71d4a96..0df8dcc 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetInfo.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetInfo.java
@@ -34,6 +34,7 @@
     private boolean isRegistered;
     private boolean memoryAllocated;
     private boolean durable;
+    private boolean correlated;
 
     public DatasetInfo(int datasetID) {
         this.indexes = new HashMap<>();
@@ -41,6 +42,7 @@
         this.datasetID = datasetID;
         this.setRegistered(false);
         this.setMemoryAllocated(false);
+        this.setCorrelated(false);
     }
 
     @Override
@@ -195,4 +197,12 @@
     public void setLastAccess(long lastAccess) {
         this.lastAccess = lastAccess;
     }
+
+    public void setCorrelated(boolean correlated) {
+        this.correlated = correlated;
+    }
+
+    public boolean isCorrelated() {
+        return correlated;
+    }
 }
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetLifecycleManager.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetLifecycleManager.java
index 37bd789..ad9f6a5 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetLifecycleManager.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetLifecycleManager.java
@@ -223,7 +223,7 @@
         if (iInfo.isOpen()) {
             ILSMIndexAccessor accessor =
                     iInfo.getIndex().createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            accessor.scheduleFlush(iInfo.getIndex().getIOOperationCallback());
+            accessor.scheduleFlush(iInfo.getIndex().getIOOperationCallback(), null);
         }
 
         // Wait for the above flush op.
@@ -417,16 +417,22 @@
         }
 
         if (asyncFlush) {
-            for (IndexInfo iInfo : dsInfo.getIndexes().values()) {
-                ILSMIndexAccessor accessor =
-                        iInfo.getIndex().createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-                accessor.scheduleFlush(iInfo.getIndex().getIOOperationCallback());
-            }
+            PrimaryIndexOperationTracker.flushDatasetIndexes(dsInfo.getDatsetIndexInfos(), dsInfo.isCorrelated());
         } else {
+            List<IndexInfo> primaryIndexes = new ArrayList<>();
             for (IndexInfo iInfo : dsInfo.getIndexes().values()) {
-                // TODO: This is not efficient since we flush the indexes sequentially.
-                // Think of a way to allow submitting the flush requests concurrently. We don't do them concurrently because this
-                // may lead to a deadlock scenario between the DatasetLifeCycleManager and the PrimaryIndexOperationTracker.
+                if (iInfo.getIndex().isPrimaryIndex()) {
+                    // primary indexes are flushed later to guarantee the correctness of the correlated merge policy
+                    primaryIndexes.add(iInfo);
+                } else {
+                    // TODO: This is not efficient since we flush the indexes sequentially.
+                    // Think of a way to allow submitting the flush requests concurrently.
+                    // We don't do them concurrently because this may lead to a deadlock scenario
+                    // between the DatasetLifeCycleManager and the PrimaryIndexOperationTracker.
+                    flushAndWaitForIO(dsInfo, iInfo);
+                }
+            }
+            for (IndexInfo iInfo : primaryIndexes) {
                 flushAndWaitForIO(dsInfo, iInfo);
             }
         }
@@ -591,4 +597,5 @@
             }
         }
     }
+
 }
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetResource.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetResource.java
index f2f3b93..5eb3c02 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetResource.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/DatasetResource.java
@@ -23,6 +23,7 @@
 import org.apache.asterix.common.dataflow.DatasetLocalResource;
 import org.apache.hyracks.api.exceptions.HyracksDataException;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndex;
+import org.apache.hyracks.storage.am.lsm.common.impls.AbstractLSMIndex;
 import org.apache.hyracks.storage.common.IIndex;
 import org.apache.hyracks.storage.common.LocalResource;
 
@@ -95,6 +96,10 @@
                     datasetInfo.setExternal(!index.hasMemoryComponents());
                     datasetInfo.setRegistered(true);
                     datasetInfo.setDurable(((ILSMIndex) index).isDurable());
+                    //TODO use a general mechanism to set correlated property when we have more
+                    // correlated merge policies
+                    datasetInfo.setCorrelated(
+                            ((AbstractLSMIndex) index).getMergePolicy() instanceof CorrelatedPrefixMergePolicy);
                 }
             }
         }
diff --git a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/PrimaryIndexOperationTracker.java b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/PrimaryIndexOperationTracker.java
index 67b25b6..4eb1c3a 100644
--- a/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/PrimaryIndexOperationTracker.java
+++ b/asterixdb/asterix-common/src/main/java/org/apache/asterix/common/context/PrimaryIndexOperationTracker.java
@@ -19,6 +19,9 @@
 
 package org.apache.asterix.common.context;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -31,6 +34,7 @@
 import org.apache.hyracks.api.exceptions.HyracksDataException;
 import org.apache.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMComponent.ComponentState;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndex;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMMemoryComponent;
@@ -141,17 +145,16 @@
 
     //This method is called sequentially by LogPage.notifyFlushTerminator in the sequence flushes were scheduled.
     public synchronized void triggerScheduleFlush(LogRecord logRecord) throws HyracksDataException {
-        for (ILSMIndex lsmIndex : dsInfo.getDatasetIndexes()) {
-            //get resource
-            ILSMIndexAccessor accessor =
-                    lsmIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+        Set<IndexInfo> indexInfos = dsInfo.getDatsetIndexInfos();
+        for (IndexInfo iInfo : indexInfos) {
             //update resource lsn
             AbstractLSMIOOperationCallback ioOpCallback =
-                    (AbstractLSMIOOperationCallback) lsmIndex.getIOOperationCallback();
+                    (AbstractLSMIOOperationCallback) iInfo.getIndex().getIOOperationCallback();
             ioOpCallback.updateLastLSN(logRecord.getLSN());
-            //schedule flush after update
-            accessor.scheduleFlush(lsmIndex.getIOOperationCallback());
         }
+
+        flushDatasetIndexes(indexInfos, dsInfo.isCorrelated());
+
         flushLogCreated = false;
     }
 
@@ -198,4 +201,63 @@
         return flushLogCreated;
     }
 
+    public static void flushDatasetIndexes(Set<IndexInfo> indexes, boolean correlated) throws HyracksDataException {
+        if (!correlated) {
+            // if not correlated, we simply schedule flushes of each index independently
+            for (IndexInfo iInfo : indexes) {
+                ILSMIndex lsmIndex = iInfo.getIndex();
+                //get resource
+                ILSMIndexAccessor accessor =
+                        lsmIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                //schedule flush after update
+                accessor.scheduleFlush(lsmIndex.getIOOperationCallback(), null);
+            }
+        } else {
+            // otherwise, we need to schedule indexes properly s.t. the primary index would depend on
+            // all secondary indexes in the same partition
+
+            // collect partitions
+            Set<Integer> partitions = new HashSet<>();
+            indexes.forEach(iInfo -> partitions.add(iInfo.getPartition()));
+            for (Integer partition : partitions) {
+                flushCorrelatedDatasetIndexes(indexes, partition);
+            }
+
+        }
+    }
+
+    private static void flushCorrelatedDatasetIndexes(Set<IndexInfo> indexes, int partition)
+            throws HyracksDataException {
+        ILSMIndex primaryIndex = null;
+        List<ILSMIOOperation> flushOps = new ArrayList<>();
+        for (IndexInfo iInfo : indexes) {
+            if (iInfo.getPartition() != partition) {
+                continue;
+            }
+            ILSMIndex lsmIndex = iInfo.getIndex();
+            if (lsmIndex.isPrimaryIndex()) {
+                primaryIndex = lsmIndex;
+            } else {
+                //get resource
+                ILSMIndexAccessor accessor =
+                        lsmIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                //schedule flush
+                ILSMIOOperation flushOp = accessor.scheduleFlush(lsmIndex.getIOOperationCallback(), null);
+                if (flushOp != null) {
+                    flushOps.add(flushOp);
+                }
+            }
+        }
+
+        if (primaryIndex != null) {
+            //get resource
+            ILSMIndexAccessor accessor =
+                    primaryIndex.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+            //schedule flush after update
+            accessor.scheduleFlush(primaryIndex.getIOOperationCallback(), flushOps);
+
+        }
+
+    }
+
 }
diff --git a/asterixdb/asterix-common/src/test/java/org/apache/asterix/test/context/CorrelatedPrefixMergePolicyTest.java b/asterixdb/asterix-common/src/test/java/org/apache/asterix/test/context/CorrelatedPrefixMergePolicyTest.java
index 9f071bb..ee795d5 100644
--- a/asterixdb/asterix-common/src/test/java/org/apache/asterix/test/context/CorrelatedPrefixMergePolicyTest.java
+++ b/asterixdb/asterix-common/src/test/java/org/apache/asterix/test/context/CorrelatedPrefixMergePolicyTest.java
@@ -236,7 +236,7 @@
                 return null;
             }
         }).when(accessor).scheduleMerge(Mockito.any(ILSMIOOperationCallback.class),
-                Mockito.anyListOf(ILSMDiskComponent.class));
+                Mockito.anyListOf(ILSMDiskComponent.class), Mockito.any());
 
         Mockito.when(index.createAccessor(Mockito.any(IModificationOperationCallback.class),
                 Mockito.any(ISearchOperationCallback.class))).thenReturn(accessor);
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTree.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTree.java
index 3775985..f5c3013 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTree.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTree.java
@@ -56,6 +56,7 @@
 import org.apache.hyracks.storage.am.lsm.common.impls.LSMComponentFileReferences;
 import org.apache.hyracks.storage.am.lsm.common.impls.LSMTreeIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.LSMTreeIndexAccessor.ICursorFactory;
+import org.apache.hyracks.storage.am.lsm.common.impls.MergeOperation;
 import org.apache.hyracks.storage.am.lsm.common.impls.TreeIndexFactory;
 import org.apache.hyracks.storage.common.IIndexBulkLoader;
 import org.apache.hyracks.storage.common.IIndexCursor;
@@ -170,7 +171,7 @@
     // The only reason to override the following method is that it uses a different context object
     // in addition, determining whether or not to keep deleted tuples is different here
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         ExternalBTreeOpContext opCtx = createOpContext(NoOpOperationCallback.INSTANCE, -1);
         opCtx.setOperation(IndexOperation.MERGE);
@@ -195,9 +196,11 @@
         LSMComponentFileReferences relMergeFileRefs =
                 fileManager.getRelMergeFileReference(firstFile.getFile().getName(), lastFile.getFile().getName());
         ILSMIndexAccessor accessor = new LSMTreeIndexAccessor(getLsmHarness(), opCtx, cursorFactory);
-        ioScheduler.scheduleOperation(new LSMBTreeMergeOperation(accessor, cursor,
+        MergeOperation mergeOp = new LSMBTreeMergeOperation(accessor, cursor,
                 relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getBloomFilterFileReference(),
-                callback, fileManager.getBaseDir().getAbsolutePath()));
+                callback, fileManager.getBaseDir().getAbsolutePath(), ctx.getDependingOps());
+        ioScheduler.scheduleOperation(mergeOp);
+        return mergeOp;
     }
 
     // This function should only be used when a transaction fail. it doesn't
@@ -369,7 +372,7 @@
 
     // Not supported
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         throw new UnsupportedOperationException("flush not supported in LSM-Disk-Only-BTree");
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTreeWithBuddy.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTreeWithBuddy.java
index ff17905..071a4bd 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTreeWithBuddy.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/ExternalBTreeWithBuddy.java
@@ -319,7 +319,7 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         throw HyracksDataException.create(ErrorCode.FLUSH_NOT_SUPPORTED_IN_EXTERNAL_INDEX);
     }
@@ -342,7 +342,7 @@
     }
 
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         ILSMIndexOperationContext bctx = createOpContext(NoOpOperationCallback.INSTANCE, 0);
         bctx.setOperation(IndexOperation.MERGE);
@@ -363,11 +363,12 @@
             keepDeleteTuples = mergingComponents.get(mergingComponents.size() - 1) != secondDiskComponents
                     .get(secondDiskComponents.size() - 1);
         }
-
-        ioScheduler.scheduleOperation(
+        ILSMIOOperation mergeOp =
                 new LSMBTreeWithBuddyMergeOperation(accessor, cursor, relMergeFileRefs.getInsertIndexFileReference(),
                         relMergeFileRefs.getDeleteIndexFileReference(), relMergeFileRefs.getBloomFilterFileReference(),
-                        callback, fileManager.getBaseDir().getAbsolutePath(), keepDeleteTuples));
+                        callback, fileManager.getBaseDir().getAbsolutePath(), keepDeleteTuples, ctx.getDependingOps());
+        ioScheduler.scheduleOperation(mergeOp);
+        return mergeOp;
     }
 
     // This method creates the appropriate opContext for the targeted version
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTree.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
index c7d45e1..00a489e 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTree.java
@@ -462,7 +462,8 @@
             LSMComponentFileReferences componentFileRefs, ILSMIOOperationCallback callback) {
         ILSMIndexAccessor accessor = createAccessor(opCtx);
         return new LSMBTreeFlushOperation(accessor, componentFileRefs.getInsertIndexFileReference(),
-                componentFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath());
+                componentFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath(),
+                opCtx.getDependingOps());
     }
 
     @Override
@@ -611,6 +612,7 @@
         }
         ITreeIndexCursor cursor = new LSMBTreeRangeSearchCursor(opCtx, returnDeletedTuples);
         return new LSMBTreeMergeOperation(accessor, cursor, mergeFileRefs.getInsertIndexFileReference(),
-                mergeFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath());
+                mergeFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath(),
+                opCtx.getDependingOps());
     }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeFlushOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeFlushOperation.java
index e3424e5..92b53de 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeFlushOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeFlushOperation.java
@@ -18,7 +18,10 @@
  */
 package org.apache.hyracks.storage.am.lsm.btree.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.FlushOperation;
@@ -27,8 +30,9 @@
     private final FileReference bloomFilterFlushTarget;
 
     public LSMBTreeFlushOperation(ILSMIndexAccessor accessor, FileReference flushTarget,
-            FileReference bloomFilterFlushTarget, ILSMIOOperationCallback callback, String indexIdentifier) {
-        super(accessor, flushTarget, callback, indexIdentifier);
+            FileReference bloomFilterFlushTarget, ILSMIOOperationCallback callback, String indexIdentifier,
+            List<ILSMIOOperation> dependingOps) {
+        super(accessor, flushTarget, callback, indexIdentifier, dependingOps);
         this.bloomFilterFlushTarget = bloomFilterFlushTarget;
     }
 
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
index ec96303..40ac7b1 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeMergeOperation.java
@@ -19,8 +19,11 @@
 
 package org.apache.hyracks.storage.am.lsm.btree.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
 import org.apache.hyracks.storage.am.common.api.ITreeIndexCursor;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.MergeOperation;
@@ -30,8 +33,9 @@
     private final FileReference bloomFilterMergeTarget;
 
     public LSMBTreeMergeOperation(ILSMIndexAccessor accessor, ITreeIndexCursor cursor, FileReference target,
-            FileReference bloomFilterMergeTarget, ILSMIOOperationCallback callback, String indexIdentifier) {
-        super(accessor, target, callback, indexIdentifier, cursor);
+            FileReference bloomFilterMergeTarget, ILSMIOOperationCallback callback, String indexIdentifier,
+            List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, cursor, dependingOps);
         this.bloomFilterMergeTarget = bloomFilterMergeTarget;
     }
 
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeWithBuddyMergeOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeWithBuddyMergeOperation.java
index f682bde..e0c1512 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeWithBuddyMergeOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-btree/src/main/java/org/apache/hyracks/storage/am/lsm/btree/impls/LSMBTreeWithBuddyMergeOperation.java
@@ -18,8 +18,11 @@
  */
 package org.apache.hyracks.storage.am.lsm.btree.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
 import org.apache.hyracks.storage.am.common.api.ITreeIndexCursor;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.MergeOperation;
@@ -32,8 +35,8 @@
 
     public LSMBTreeWithBuddyMergeOperation(ILSMIndexAccessor accessor, ITreeIndexCursor cursor, FileReference target,
             FileReference buddyBtreeMergeTarget, FileReference bloomFilterMergeTarget, ILSMIOOperationCallback callback,
-            String indexIdentifier, boolean keepDeletedTuples) {
-        super(accessor, target, callback, indexIdentifier, cursor);
+            String indexIdentifier, boolean keepDeletedTuples, List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, cursor, dependingOps);
         this.buddyBtreeMergeTarget = buddyBtreeMergeTarget;
         this.bloomFilterMergeTarget = bloomFilterMergeTarget;
         this.keepDeletedTuples = keepDeletedTuples;
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMHarness.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMHarness.java
index 89c8cb9..380b2f2 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMHarness.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMHarness.java
@@ -105,10 +105,12 @@
      *
      * @param ctx
      * @param callback
+     * @return The scheduled merge operation, used for the caller to track its status
      * @throws HyracksDataException
      * @throws IndexException
      */
-    void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback) throws HyracksDataException;
+    ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+            throws HyracksDataException;
 
     /**
      * Schedule full merge
@@ -135,9 +137,11 @@
      *
      * @param ctx
      * @param callback
+     * @return The scheduled flush operation, used for the caller to track its status
      * @throws HyracksDataException
      */
-    void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback) throws HyracksDataException;
+    ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+            throws HyracksDataException;
 
     /**
      * Perform a flush
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
index c2ae786..ff1613b 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIOOperation.java
@@ -18,6 +18,7 @@
  */
 package org.apache.hyracks.storage.am.lsm.common.api;
 
+import java.util.List;
 import java.util.concurrent.Callable;
 
 import org.apache.hyracks.api.exceptions.HyracksDataException;
@@ -63,7 +64,19 @@
     FileReference getTarget();
 
     /**
+     * <<<<<<< HEAD
+     *
      * @return the accessor of the operation
      */
     ILSMIndexAccessor getAccessor();
+
+    /**
+     * @return whether this operation has finished
+     */
+    boolean isFinished();
+
+    /**
+     * @return a list of operations that this operation depends on
+     */
+    List<ILSMIOOperation> getDependingOps();
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndex.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndex.java
index addeb27..5f43bcd 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndex.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndex.java
@@ -67,11 +67,13 @@
 
     public void scanDiskComponents(ILSMIndexOperationContext ctx, IIndexCursor cursor) throws HyracksDataException;
 
-    void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback) throws HyracksDataException;
+    ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+            throws HyracksDataException;
 
     ILSMDiskComponent flush(ILSMIOOperation operation) throws HyracksDataException;
 
-    void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback) throws HyracksDataException;
+    ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+            throws HyracksDataException;
 
     ILSMDiskComponent merge(ILSMIOOperation operation) throws HyracksDataException;
 
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
index b8d64af..b303a39 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexAccessor.java
@@ -46,9 +46,13 @@
      *
      * @param callback
      *            the IO operation callback
+     * @param dependingOps
+     *            other operations that this operation depends on
+     * @return The scheduled flush operation
      * @throws HyracksDataException
      */
-    void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException;
+    ILSMIOOperation scheduleFlush(ILSMIOOperationCallback callback, List<ILSMIOOperation> dependingOps)
+            throws HyracksDataException;
 
     /**
      * Schedule a merge operation
@@ -57,11 +61,13 @@
      *            the merge operation callback
      * @param components
      *            the components to be merged
+     * @param dependingOps
+     *            other operations that this operation depends on
+     * @return The scheduled merge operation
      * @throws HyracksDataException
-     * @throws IndexException
      */
-    void scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components)
-            throws HyracksDataException;
+    ILSMIOOperation scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components,
+            List<ILSMIOOperation> dependingOps) throws HyracksDataException;
 
     /**
      * Schedule a full merge
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
index 5b0378a..66af93f 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/api/ILSMIndexOperationContext.java
@@ -56,4 +56,8 @@
     PermutingTupleReference getFilterTuple();
 
     MultiComparator getFilterCmp();
+
+    List<ILSMIOOperation> getDependingOps();
+
+    void setDependingOps(List<ILSMIOOperation> dependingOps);
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractIoOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractIoOperation.java
index aee46f0..1d13c94 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractIoOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractIoOperation.java
@@ -18,6 +18,10 @@
  */
 package org.apache.hyracks.storage.am.lsm.common.impls;
 
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.hyracks.api.exceptions.HyracksDataException;
 import org.apache.hyracks.api.io.FileReference;
 import org.apache.hyracks.api.io.IODeviceHandle;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
@@ -30,13 +34,32 @@
     protected final FileReference target;
     protected final ILSMIOOperationCallback callback;
     protected final String indexIdentifier;
+    protected final List<ILSMIOOperation> dependingOps;
+
+    protected AtomicBoolean isFinished = new AtomicBoolean(false);
 
     public AbstractIoOperation(ILSMIndexAccessor accessor, FileReference target, ILSMIOOperationCallback callback,
-            String indexIdentifier) {
+            String indexIdentifier, List<ILSMIOOperation> dependingOps) {
         this.accessor = accessor;
         this.target = target;
         this.callback = callback;
         this.indexIdentifier = indexIdentifier;
+        this.dependingOps = dependingOps;
+    }
+
+    protected abstract void callInternal() throws HyracksDataException;
+
+    @Override
+    public Boolean call() throws HyracksDataException {
+        try {
+            callInternal();
+        } finally {
+            synchronized (this) {
+                isFinished.set(true);
+                notifyAll();
+            }
+        }
+        return true;
     }
 
     @Override
@@ -63,4 +86,14 @@
     public String getIndexIdentifier() {
         return indexIdentifier;
     }
+
+    @Override
+    public List<ILSMIOOperation> getDependingOps() {
+        return dependingOps;
+    }
+
+    @Override
+    public boolean isFinished() {
+        return isFinished.get();
+    }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
index dc64f9b..e7b21cb 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndex.java
@@ -86,6 +86,7 @@
     protected final int[] treeFields;
     protected final int[] filterFields;
     protected final boolean durable;
+    protected final ILSMMergePolicy mergePolicy;
     protected boolean isActive;
     protected final AtomicBoolean[] flushRequests;
     protected boolean memoryComponentsAllocated = false;
@@ -113,6 +114,7 @@
         this.inactiveDiskComponents = new LinkedList<>();
         this.durable = durable;
         this.tracer = tracer;
+        this.mergePolicy = mergePolicy;
         lsmHarness = new LSMHarness(this, mergePolicy, opTracker, diskBufferCache.isReplicationEnabled(), tracer);
         isActive = false;
         diskComponents = new ArrayList<>();
@@ -135,6 +137,7 @@
         this.ioScheduler = ioScheduler;
         this.ioOpCallback = ioOpCallback;
         this.durable = durable;
+        this.mergePolicy = mergePolicy;
         lsmHarness = new ExternalIndexHarness(this, mergePolicy, opTracker, diskBufferCache.isReplicationEnabled());
         isActive = false;
         diskComponents = new LinkedList<>();
@@ -199,7 +202,7 @@
     protected void flushMemoryComponent() throws HyracksDataException {
         BlockingIOOperationCallbackWrapper cb = new BlockingIOOperationCallbackWrapper(ioOpCallback);
         ILSMIndexAccessor accessor = createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-        accessor.scheduleFlush(cb);
+        accessor.scheduleFlush(cb, null);
         try {
             cb.waitForIO();
         } catch (InterruptedException e) {
@@ -326,19 +329,21 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         LSMComponentFileReferences componentFileRefs = fileManager.getRelFlushFileReference();
         AbstractLSMIndexOperationContext opCtx =
                 createOpContext(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
         opCtx.setOperation(ctx.getOperation());
         opCtx.getComponentHolder().addAll(ctx.getComponentHolder());
+        opCtx.setDependingOps(ctx.getDependingOps());
         ILSMIOOperation flushOp = createFlushOperation(opCtx, componentFileRefs, callback);
         ioScheduler.scheduleOperation(TracedIOOperation.wrap(flushOp, tracer));
+        return flushOp;
     }
 
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         List<ILSMComponent> mergingComponents = ctx.getComponentHolder();
         // merge must create a different op ctx
@@ -346,11 +351,13 @@
                 createOpContext(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
         opCtx.setOperation(ctx.getOperation());
         opCtx.getComponentHolder().addAll(mergingComponents);
+        opCtx.setDependingOps(ctx.getDependingOps());
         ILSMDiskComponent firstComponent = (ILSMDiskComponent) mergingComponents.get(0);
         ILSMDiskComponent lastComponent = (ILSMDiskComponent) mergingComponents.get(mergingComponents.size() - 1);
         LSMComponentFileReferences mergeFileRefs = getMergeFileReferences(firstComponent, lastComponent);
-        ILSMIOOperation mergeOp = createMergeOperation(opCtx, mergeFileRefs, callback);
+        MergeOperation mergeOp = (MergeOperation) createMergeOperation(opCtx, mergeFileRefs, callback);
         ioScheduler.scheduleOperation(TracedIOOperation.wrap(mergeOp, tracer));
+        return mergeOp;
     }
 
     private void addOperationalMutableComponents(List<ILSMComponent> operationalComponents) {
@@ -628,6 +635,10 @@
                 : doMerge(operation);
     }
 
+    public ILSMMergePolicy getMergePolicy() {
+        return mergePolicy;
+    }
+
     public abstract Set<String> getLSMComponentPhysicalFiles(ILSMComponent newComponent);
 
     protected abstract void allocateMemoryComponent(ILSMMemoryComponent c) throws HyracksDataException;
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndexOperationContext.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndexOperationContext.java
index 065d465..5fdeafd 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndexOperationContext.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/AbstractLSMIndexOperationContext.java
@@ -27,6 +27,7 @@
 import org.apache.hyracks.storage.am.common.tuples.PermutingTupleReference;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMComponent;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMDiskComponent;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexOperationContext;
 import org.apache.hyracks.storage.common.IModificationOperationCallback;
 import org.apache.hyracks.storage.common.ISearchOperationCallback;
@@ -47,6 +48,7 @@
     protected IndexOperation op;
     protected boolean accessingComponents = false;
     protected ISearchPredicate searchPredicate;
+    protected final List<ILSMIOOperation> dependingOps;
 
     public AbstractLSMIndexOperationContext(int[] treeFields, int[] filterFields,
             IBinaryComparatorFactory[] filterCmpFactories, ISearchOperationCallback searchCallback,
@@ -56,6 +58,7 @@
         this.componentHolder = new LinkedList<>();
         this.componentsToBeMerged = new LinkedList<>();
         this.componentsToBeReplicated = new LinkedList<>();
+        this.dependingOps = new LinkedList<>();
         if (filterFields != null) {
             indexTuple = new PermutingTupleReference(treeFields);
             filterCmp = MultiComparator.create(filterCmpFactories);
@@ -153,4 +156,17 @@
     public ISearchPredicate getSearchPredicate() {
         return searchPredicate;
     }
+
+    @Override
+    public List<ILSMIOOperation> getDependingOps() {
+        return dependingOps;
+    }
+
+    @Override
+    public void setDependingOps(List<ILSMIOOperation> dependingOps) {
+        this.dependingOps.clear();
+        if (dependingOps != null) {
+            this.dependingOps.addAll(dependingOps);
+        }
+    }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ConstantMergePolicy.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ConstantMergePolicy.java
index 847b882..7ac9bfb 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ConstantMergePolicy.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ConstantMergePolicy.java
@@ -49,7 +49,7 @@
         } else if (immutableComponents.size() >= numComponents) {
             ILSMIndexAccessor accessor =
                     index.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            accessor.scheduleMerge(index.getIOOperationCallback(), immutableComponents);
+            accessor.scheduleMerge(index.getIOOperationCallback(), immutableComponents, null);
         }
     }
 
@@ -106,7 +106,7 @@
             }
             ILSMIndexAccessor accessor =
                     index.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            accessor.scheduleMerge(index.getIOOperationCallback(), immutableComponents);
+            accessor.scheduleMerge(index.getIOOperationCallback(), immutableComponents, null);
             return true;
         }
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ExternalIndexHarness.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ExternalIndexHarness.java
index 2f65b18..b93d943 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ExternalIndexHarness.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ExternalIndexHarness.java
@@ -203,13 +203,13 @@
     }
 
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         if (!getAndEnterComponents(ctx, LSMOperationType.MERGE, true)) {
             callback.afterFinalize(LSMOperationType.MERGE, null);
-            return;
+            return null;
         }
-        lsmIndex.scheduleMerge(ctx, callback);
+        return lsmIndex.scheduleMerge(ctx, callback);
     }
 
     @Override
@@ -297,9 +297,10 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         callback.afterFinalize(LSMOperationType.FLUSH, null);
+        return null;
     }
 
     @Override
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/FlushOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/FlushOperation.java
index 7b7f950..750c690 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/FlushOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/FlushOperation.java
@@ -18,6 +18,7 @@
  */
 package org.apache.hyracks.storage.am.lsm.common.impls;
 
+import java.util.List;
 import java.util.Objects;
 
 import org.apache.hyracks.api.exceptions.HyracksDataException;
@@ -30,14 +31,13 @@
 public class FlushOperation extends AbstractIoOperation implements Comparable<ILSMIOOperation> {
 
     public FlushOperation(ILSMIndexAccessor accessor, FileReference target, ILSMIOOperationCallback callback,
-            String indexIdentifier) {
-        super(accessor, target, callback, indexIdentifier);
+            String indexIdentifier, List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, dependingOps);
     }
 
     @Override
-    public Boolean call() throws HyracksDataException {
+    protected void callInternal() throws HyracksDataException {
         accessor.flush(this);
-        return true;
     }
 
     @Override
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMHarness.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMHarness.java
index 1069f8f..bc3a5a1 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMHarness.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMHarness.java
@@ -500,13 +500,13 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         if (!getAndEnterComponents(ctx, LSMOperationType.FLUSH, true)) {
             callback.afterFinalize(LSMOperationType.FLUSH, null);
-            return;
+            return null;
         }
-        lsmIndex.scheduleFlush(ctx, callback);
+        return lsmIndex.scheduleFlush(ctx, callback);
     }
 
     @Override
@@ -519,6 +519,7 @@
         boolean failedOperation = false;
         try {
             newComponent = lsmIndex.flush(operation);
+            waitForDependingOps(operation);
             operation.getCallback().afterOperation(LSMOperationType.FLUSH, null, newComponent);
             newComponent.markAsValid(lsmIndex.isDurable());
         } catch (Throwable e) {
@@ -537,13 +538,13 @@
     }
 
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         if (!getAndEnterComponents(ctx, LSMOperationType.MERGE, true)) {
             callback.afterFinalize(LSMOperationType.MERGE, null);
-            return;
+            return null;
         }
-        lsmIndex.scheduleMerge(ctx, callback);
+        return lsmIndex.scheduleMerge(ctx, callback);
     }
 
     @Override
@@ -570,6 +571,7 @@
         boolean failedOperation = false;
         try {
             newComponent = lsmIndex.merge(operation);
+            waitForDependingOps(operation);
             operation.getCallback().afterOperation(LSMOperationType.MERGE, ctx.getComponentHolder(), newComponent);
             newComponent.markAsValid(lsmIndex.isDurable());
         } catch (Throwable e) {
@@ -754,6 +756,32 @@
         }
     }
 
+    /**
+     * Wait for depending operations to finish.
+     *
+     * @param op
+     */
+    private void waitForDependingOps(ILSMIOOperation op) throws HyracksDataException {
+        List<ILSMIOOperation> dependingOps = op.getDependingOps();
+        if (dependingOps == null) {
+            return;
+        }
+        for (ILSMIOOperation dependingOp : dependingOps) {
+            if (dependingOp != null && !dependingOp.isFinished()) {
+                synchronized (dependingOp) {
+                    while (!dependingOp.isFinished()) {
+                        try {
+                            dependingOp.wait();
+                        } catch (InterruptedException e) {
+                            Thread.currentThread().interrupt();
+                            throw HyracksDataException.create(e);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     @Override
     public void deleteComponents(ILSMIndexOperationContext ctx, Predicate<ILSMComponent> predicate)
             throws HyracksDataException {
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
index c0fd443..f008fde 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/LSMTreeIndexAccessor.java
@@ -135,18 +135,21 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
+    public ILSMIOOperation scheduleFlush(ILSMIOOperationCallback callback, List<ILSMIOOperation> dependingOps)
+            throws HyracksDataException {
         ctx.setOperation(IndexOperation.FLUSH);
-        lsmHarness.scheduleFlush(ctx, callback);
+        ctx.setDependingOps(dependingOps);
+        return lsmHarness.scheduleFlush(ctx, callback);
     }
 
     @Override
-    public void scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components)
-            throws HyracksDataException {
+    public ILSMIOOperation scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components,
+            List<ILSMIOOperation> dependingOps) throws HyracksDataException {
         ctx.setOperation(IndexOperation.MERGE);
         ctx.getComponentsToBeMerged().clear();
         ctx.getComponentsToBeMerged().addAll(components);
-        lsmHarness.scheduleMerge(ctx, callback);
+        ctx.setDependingOps(dependingOps);
+        return lsmHarness.scheduleMerge(ctx, callback);
     }
 
     @Override
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/MergeOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/MergeOperation.java
index c83d534..2210fd0 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/MergeOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/MergeOperation.java
@@ -23,6 +23,7 @@
 import org.apache.hyracks.api.exceptions.HyracksDataException;
 import org.apache.hyracks.api.io.FileReference;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.common.IIndexCursor;
@@ -31,8 +32,8 @@
     protected final IIndexCursor cursor;
 
     public MergeOperation(ILSMIndexAccessor accessor, FileReference target, ILSMIOOperationCallback callback,
-            String indexIdentifier, IIndexCursor cursor) {
-        super(accessor, target, callback, indexIdentifier);
+            String indexIdentifier, IIndexCursor cursor, List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, dependingOps);
         this.cursor = cursor;
     }
 
@@ -41,12 +42,6 @@
     }
 
     @Override
-    public Boolean call() throws HyracksDataException {
-        accessor.merge(this);
-        return true;
-    }
-
-    @Override
     public LSMIOOpertionType getIOOpertionType() {
         return LSMIOOpertionType.MERGE;
     }
@@ -54,4 +49,10 @@
     public IIndexCursor getCursor() {
         return cursor;
     }
+
+    @Override
+    protected void callInternal() throws HyracksDataException {
+        accessor.merge(this);
+
+    }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/PrefixMergePolicy.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/PrefixMergePolicy.java
index 7d7266e..f159232 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/PrefixMergePolicy.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/PrefixMergePolicy.java
@@ -247,7 +247,7 @@
         Collections.reverse(mergableComponents);
         ILSMIndexAccessor accessor =
                 index.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-        accessor.scheduleMerge(index.getIOOperationCallback(), mergableComponents);
+        accessor.scheduleMerge(index.getIOOperationCallback(), mergableComponents, null);
     }
 
     /**
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
index 85081a1..7cdcc52 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/ThreadCountingTracker.java
@@ -59,7 +59,7 @@
                 && index.hasFlushRequestForCurrentMutableComponent()) {
             ILSMIndexAccessor accessor =
                     index.createAccessor(NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
-            accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+            accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
         }
     }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/TracedIOOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/TracedIOOperation.java
index 9cc8022..3e35e51 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/TracedIOOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-common/src/main/java/org/apache/hyracks/storage/am/lsm/common/impls/TracedIOOperation.java
@@ -19,6 +19,7 @@
 
 package org.apache.hyracks.storage.am.lsm.common.impls;
 
+import java.util.List;
 import java.util.logging.Logger;
 
 import org.apache.hyracks.api.exceptions.HyracksDataException;
@@ -100,6 +101,16 @@
     public ILSMIndexAccessor getAccessor() {
         return ioOp.getAccessor();
     }
+
+    @Override
+    public boolean isFinished() {
+        return ioOp.isFinished();
+    }
+
+    @Override
+    public List<ILSMIOOperation> getDependingOps() {
+        return ioOp.getDependingOps();
+    }
 }
 
 class ComparableTracedIOOperation extends TracedIOOperation implements Comparable<ILSMIOOperation> {
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
index eb3924c..60da50a 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndex.java
@@ -691,17 +691,20 @@
             LSMComponentFileReferences componentFileRefs, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         return new LSMInvertedIndexFlushOperation(new LSMInvertedIndexAccessor(getLsmHarness(), opCtx),
-                componentFileRefs.getInsertIndexFileReference(), componentFileRefs.getDeleteIndexFileReference(),
-                componentFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath());
+                componentFileRefs.getInsertIndexFileReference(),
+                componentFileRefs.getDeleteIndexFileReference(), componentFileRefs.getBloomFilterFileReference(),
+                callback, fileManager.getBaseDir().getAbsolutePath(), opCtx.getDependingOps());
     }
 
     @Override
     protected ILSMIOOperation createMergeOperation(AbstractLSMIndexOperationContext opCtx,
-            LSMComponentFileReferences mergeFileRefs, ILSMIOOperationCallback callback) throws HyracksDataException {
+            LSMComponentFileReferences mergeFileRefs,
+            ILSMIOOperationCallback callback) throws HyracksDataException {
         ILSMIndexAccessor accessor = new LSMInvertedIndexAccessor(getLsmHarness(), opCtx);
         IIndexCursor cursor = new LSMInvertedIndexRangeSearchCursor(opCtx);
-        return new LSMInvertedIndexMergeOperation(accessor, cursor, mergeFileRefs.getInsertIndexFileReference(),
-                mergeFileRefs.getDeleteIndexFileReference(), mergeFileRefs.getBloomFilterFileReference(), callback,
-                fileManager.getBaseDir().getAbsolutePath());
+        return new LSMInvertedIndexMergeOperation(accessor, cursor,
+                mergeFileRefs.getInsertIndexFileReference(), mergeFileRefs.getDeleteIndexFileReference(),
+                mergeFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath(),
+                opCtx.getDependingOps());
     }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
index 61fc84e..242bc83 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexAccessor.java
@@ -85,9 +85,11 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIOOperationCallback callback) throws HyracksDataException {
+    public ILSMIOOperation scheduleFlush(ILSMIOOperationCallback callback, List<ILSMIOOperation> dependingOps)
+            throws HyracksDataException {
         ctx.setOperation(IndexOperation.FLUSH);
-        lsmHarness.scheduleFlush(ctx, callback);
+        ctx.setDependingOps(dependingOps);
+        return lsmHarness.scheduleFlush(ctx, callback);
     }
 
     @Override
@@ -96,12 +98,13 @@
     }
 
     @Override
-    public void scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components)
-            throws HyracksDataException {
+    public ILSMIOOperation scheduleMerge(ILSMIOOperationCallback callback, List<ILSMDiskComponent> components,
+            List<ILSMIOOperation> dependingOps) throws HyracksDataException {
         ctx.setOperation(IndexOperation.MERGE);
         ctx.getComponentsToBeMerged().clear();
         ctx.getComponentsToBeMerged().addAll(components);
-        lsmHarness.scheduleMerge(ctx, callback);
+        ctx.setDependingOps(dependingOps);
+        return lsmHarness.scheduleMerge(ctx, callback);
     }
 
     @Override
@@ -116,6 +119,7 @@
     @Override
     public void scheduleFullMerge(ILSMIOOperationCallback callback) throws HyracksDataException {
         ctx.setOperation(IndexOperation.FULL_MERGE);
+        ctx.setDependingOps(null);
         lsmHarness.scheduleFullMerge(ctx, callback);
     }
 
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
index 2106f6a..30e1cec 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexFlushOperation.java
@@ -19,7 +19,10 @@
 
 package org.apache.hyracks.storage.am.lsm.invertedindex.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.FlushOperation;
@@ -30,8 +33,8 @@
 
     public LSMInvertedIndexFlushOperation(ILSMIndexAccessor accessor, FileReference flushTarget,
             FileReference deletedKeysBTreeFlushTarget, FileReference bloomFilterFlushTarget,
-            ILSMIOOperationCallback callback, String indexIdentifier) {
-        super(accessor, flushTarget, callback, indexIdentifier);
+            ILSMIOOperationCallback callback, String indexIdentifier, List<ILSMIOOperation> dependingOps) {
+        super(accessor, flushTarget, callback, indexIdentifier, dependingOps);
         this.deletedKeysBTreeFlushTarget = deletedKeysBTreeFlushTarget;
         this.bloomFilterFlushTarget = bloomFilterFlushTarget;
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
index 2c1db0f..8361f24 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/org/apache/hyracks/storage/am/lsm/invertedindex/impls/LSMInvertedIndexMergeOperation.java
@@ -19,7 +19,10 @@
 
 package org.apache.hyracks.storage.am.lsm.invertedindex.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.MergeOperation;
@@ -31,8 +34,8 @@
 
     public LSMInvertedIndexMergeOperation(ILSMIndexAccessor accessor, IIndexCursor cursor, FileReference target,
             FileReference deletedKeysBTreeMergeTarget, FileReference bloomFilterMergeTarget,
-            ILSMIOOperationCallback callback, String indexIdentifier) {
-        super(accessor, target, callback, indexIdentifier, cursor);
+            ILSMIOOperationCallback callback, String indexIdentifier, List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, cursor, dependingOps);
         this.deletedKeysBTreeMergeTarget = deletedKeysBTreeMergeTarget;
         this.bloomFilterMergeTarget = bloomFilterMergeTarget;
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/ExternalRTree.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/ExternalRTree.java
index 6595403..110d873 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/ExternalRTree.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/ExternalRTree.java
@@ -416,7 +416,7 @@
 
     // Not supported
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         throw new UnsupportedOperationException("flush not supported in LSM-Disk-Only-RTree");
     }
@@ -623,7 +623,7 @@
     // The only change the the schedule merge is the method used to create the
     // opCtx. first line <- in schedule merge, we->
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
         ILSMIndexOperationContext rctx = createOpContext(NoOpOperationCallback.INSTANCE, -1);
         rctx.setOperation(IndexOperation.MERGE);
@@ -634,10 +634,12 @@
                         (ILSMDiskComponent) mergingComponents.get(mergingComponents.size() - 1));
         ILSMIndexAccessor accessor = new LSMRTreeAccessor(getLsmHarness(), rctx, buddyBTreeFields);
         // create the merge operation.
-        LSMRTreeMergeOperation mergeOp = new LSMRTreeMergeOperation(accessor, cursor,
-                relMergeFileRefs.getInsertIndexFileReference(), relMergeFileRefs.getDeleteIndexFileReference(),
-                relMergeFileRefs.getBloomFilterFileReference(), callback, fileManager.getBaseDir().getAbsolutePath());
+        ILSMIOOperation mergeOp =
+                new LSMRTreeMergeOperation(accessor, cursor, relMergeFileRefs.getInsertIndexFileReference(),
+                        relMergeFileRefs.getDeleteIndexFileReference(), relMergeFileRefs.getBloomFilterFileReference(),
+                        callback, fileManager.getBaseDir().getAbsolutePath(), ctx.getDependingOps());
         ioScheduler.scheduleOperation(mergeOp);
+        return mergeOp;
     }
 
     @Override
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
index ca0e4e1..a4d6a65 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTree.java
@@ -420,7 +420,7 @@
         LSMRTreeAccessor accessor = new LSMRTreeAccessor(getLsmHarness(), opCtx, buddyBTreeFields);
         return new LSMRTreeFlushOperation(accessor, componentFileRefs.getInsertIndexFileReference(),
                 componentFileRefs.getDeleteIndexFileReference(), componentFileRefs.getBloomFilterFileReference(),
-                callback, fileManager.getBaseDir().getAbsolutePath());
+                callback, fileManager.getBaseDir().getAbsolutePath(), opCtx.getDependingOps());
     }
 
     @Override
@@ -430,6 +430,6 @@
         ILSMIndexAccessor accessor = new LSMRTreeAccessor(getLsmHarness(), opCtx, buddyBTreeFields);
         return new LSMRTreeMergeOperation(accessor, cursor, mergeFileRefs.getInsertIndexFileReference(),
                 mergeFileRefs.getDeleteIndexFileReference(), mergeFileRefs.getBloomFilterFileReference(), callback,
-                fileManager.getBaseDir().getAbsolutePath());
+                fileManager.getBaseDir().getAbsolutePath(), opCtx.getDependingOps());
     }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
index 6991c56..a08d854 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeFlushOperation.java
@@ -18,7 +18,10 @@
  */
 package org.apache.hyracks.storage.am.lsm.rtree.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.FlushOperation;
@@ -29,8 +32,9 @@
     private final FileReference bloomFilterFlushTarget;
 
     public LSMRTreeFlushOperation(ILSMIndexAccessor accessor, FileReference flushTarget, FileReference btreeFlushTarget,
-            FileReference bloomFilterFlushTarget, ILSMIOOperationCallback callback, String indexIdentifier) {
-        super(accessor, flushTarget, callback, indexIdentifier);
+            FileReference bloomFilterFlushTarget, ILSMIOOperationCallback callback, String indexIdentifier,
+            List<ILSMIOOperation> dependingOps) {
+        super(accessor, flushTarget, callback, indexIdentifier, dependingOps);
         this.btreeFlushTarget = btreeFlushTarget;
         this.bloomFilterFlushTarget = bloomFilterFlushTarget;
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
index 83872cf..a07e57b 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeMergeOperation.java
@@ -18,8 +18,11 @@
  */
 package org.apache.hyracks.storage.am.lsm.rtree.impls;
 
+import java.util.List;
+
 import org.apache.hyracks.api.io.FileReference;
 import org.apache.hyracks.storage.am.common.api.ITreeIndexCursor;
+import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperation;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIOOperationCallback;
 import org.apache.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
 import org.apache.hyracks.storage.am.lsm.common.impls.MergeOperation;
@@ -30,8 +33,8 @@
 
     public LSMRTreeMergeOperation(ILSMIndexAccessor accessor, ITreeIndexCursor cursor, FileReference target,
             FileReference btreeMergeTarget, FileReference bloomFilterMergeTarget, ILSMIOOperationCallback callback,
-            String indexIdentifier) {
-        super(accessor, target, callback, indexIdentifier, cursor);
+            String indexIdentifier, List<ILSMIOOperation> dependingOps) {
+        super(accessor, target, callback, indexIdentifier, cursor, dependingOps);
         this.btreeMergeTarget = btreeMergeTarget;
         this.bloomFilterMergeTarget = bloomFilterMergeTarget;
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
index 1e15455..a18f10c 100644
--- a/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
+++ b/hyracks-fullstack/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/org/apache/hyracks/storage/am/lsm/rtree/impls/LSMRTreeWithAntiMatterTuples.java
@@ -332,7 +332,7 @@
             throws HyracksDataException {
         ILSMIndexAccessor accessor = new LSMTreeIndexAccessor(getLsmHarness(), opCtx, cursorFactory);
         return new LSMRTreeFlushOperation(accessor, componentFileRefs.getInsertIndexFileReference(), null, null,
-                callback, fileManager.getBaseDir().getAbsolutePath());
+                callback, fileManager.getBaseDir().getAbsolutePath(), opCtx.getDependingOps());
     }
 
     @Override
@@ -346,6 +346,6 @@
         ITreeIndexCursor cursor = new LSMRTreeWithAntiMatterTuplesSearchCursor(opCtx, returnDeletedTuples);
         ILSMIndexAccessor accessor = new LSMTreeIndexAccessor(getLsmHarness(), opCtx, cursorFactory);
         return new MergeOperation(accessor, mergeFileRefs.getInsertIndexFileReference(), callback,
-                fileManager.getBaseDir().getAbsolutePath(), cursor);
+                fileManager.getBaseDir().getAbsolutePath(), cursor, opCtx.getDependingOps());
     }
 }
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFileManagerTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFileManagerTest.java
index 5d6d8de..4f7515e 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFileManagerTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFileManagerTest.java
@@ -72,7 +72,7 @@
         accessor.insert(tuple);
 
         // Flush to generate a disk component
-        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
 
         // Make sure the disk component was generated
         LSMBTree btree = (LSMBTree) ctx.getIndex();
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFilterMergeTestDriver.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFilterMergeTestDriver.java
index c5eb97c..98faf01 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFilterMergeTestDriver.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeFilterMergeTestDriver.java
@@ -117,7 +117,7 @@
 
                 StubIOOperationCallback stub = new StubIOOperationCallback();
                 BlockingIOOperationCallbackWrapper waiter = new BlockingIOOperationCallbackWrapper(stub);
-                accessor.scheduleFlush(waiter);
+                accessor.scheduleFlush(waiter, null);
                 waiter.waitForIO();
                 if (minMax != null) {
                     Pair<ITupleReference, ITupleReference> obsMinMax =
@@ -146,7 +146,7 @@
                 }
             }
             accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                    ((LSMBTree) ctx.getIndex()).getDiskComponents());
+                    ((LSMBTree) ctx.getIndex()).getDiskComponents(), null);
 
             flushedComponents = ((LSMBTree) ctx.getIndex()).getDiskComponents();
             Pair<ITupleReference, ITupleReference> mergedMinMax =
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeMergeTestDriver.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeMergeTestDriver.java
index 7dac1e5..15dbfdb 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeMergeTestDriver.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeMergeTestDriver.java
@@ -76,7 +76,7 @@
 
             ILSMIndexAccessor accessor = (ILSMIndexAccessor) ctx.getIndexAccessor();
             accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                    ((LSMBTree) ctx.getIndex()).getDiskComponents());
+                    ((LSMBTree) ctx.getIndex()).getDiskComponents(), null);
 
             orderedIndexTestUtils.checkPointSearches(ctx);
             orderedIndexTestUtils.checkScan(ctx);
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
index b633614..11ecf0b 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeModificationOperationCallbackTest.java
@@ -81,7 +81,7 @@
             }
 
             if (j == 1) {
-                accessor.scheduleFlush(ioOpCallback);
+                accessor.scheduleFlush(ioOpCallback, null);
                 ioOpCallback.waitForIO();
                 isFoundNull = true;
             } else {
@@ -94,7 +94,7 @@
             }
 
             if (j == 1) {
-                accessor.scheduleFlush(ioOpCallback);
+                accessor.scheduleFlush(ioOpCallback, null);
                 ioOpCallback.waitForIO();
                 isFoundNull = true;
             } else {
@@ -106,7 +106,7 @@
                 accessor.delete(tuple);
             }
 
-            accessor.scheduleFlush(ioOpCallback);
+            accessor.scheduleFlush(ioOpCallback, null);
             ioOpCallback.waitForIO();
         }
     }
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeScanDiskComponentsTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeScanDiskComponentsTest.java
index acbeaef..f3cf9de 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeScanDiskComponentsTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeScanDiskComponentsTest.java
@@ -19,7 +19,7 @@
 
 package org.apache.hyracks.storage.am.lsm.btree;
 
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 import java.io.ByteArrayInputStream;
 import java.io.DataInput;
@@ -116,17 +116,17 @@
         //component 2 contains 1 and 2
         upsertTuple(ctx, fieldSerdes, getValue(1, fieldSerdes));
         upsertTuple(ctx, fieldSerdes, getValue(2, fieldSerdes));
-        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
 
         //component 1 contains 1 and -2
         upsertTuple(ctx, fieldSerdes, getValue(1, fieldSerdes));
         deleteTuple(ctx, fieldSerdes, getValue(2, fieldSerdes));
-        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
 
         //component 0 contains 2 and 3
         upsertTuple(ctx, fieldSerdes, getValue(3, fieldSerdes));
         upsertTuple(ctx, fieldSerdes, getValue(2, fieldSerdes));
-        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
 
         LSMBTree btree = (LSMBTree) ctx.getIndex();
         Assert.assertEquals("Check disk components", 3, btree.getDiskComponents().size());
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceScanDiskComponentsTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceScanDiskComponentsTest.java
index fbcbcc2..a7efd6d 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceScanDiskComponentsTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceScanDiskComponentsTest.java
@@ -19,7 +19,7 @@
 
 package org.apache.hyracks.storage.am.lsm.btree;
 
-import static org.junit.Assert.fail;
+import static org.junit.Assert.*;
 
 import java.io.ByteArrayInputStream;
 import java.io.DataInput;
@@ -352,7 +352,7 @@
         op1.performOperation(ctx, AccessMethodTestsConfig.BTREE_NUM_TUPLES_TO_INSERT);
         op2.performOperation(ctx,
                 AccessMethodTestsConfig.BTREE_NUM_TUPLES_TO_INSERT / AccessMethodTestsConfig.BTREE_NUM_INSERT_ROUNDS);
-        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback());
+        accessor.scheduleFlush(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(), null);
 
         LSMBTree btree = (LSMBTree) ctx.getIndex();
         Assert.assertEquals("Check disk components", 1, btree.getDiskComponents().size());
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceTest.java
index e059faa..adcb3d9 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/LSMBTreeUpdateInPlaceTest.java
@@ -109,7 +109,7 @@
             }
 
             if (j == 1) {
-                lsmAccessor.scheduleFlush(ioOpCallback);
+                lsmAccessor.scheduleFlush(ioOpCallback, null);
                 ioOpCallback.waitForIO();
                 isFoundNull = true;
                 isUpdated = false;
@@ -124,7 +124,7 @@
             }
 
             if (j == 1) {
-                lsmAccessor.scheduleFlush(ioOpCallback);
+                lsmAccessor.scheduleFlush(ioOpCallback, null);
                 ioOpCallback.waitForIO();
             } else {
                 isFoundNull = false;
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/impl/TestLsmBtree.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/impl/TestLsmBtree.java
index 6c1a406..0e16280 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/impl/TestLsmBtree.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/impl/TestLsmBtree.java
@@ -103,17 +103,19 @@
     }
 
     @Override
-    public void scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleFlush(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        super.scheduleFlush(ctx, callback);
+        ILSMIOOperation flushOp = super.scheduleFlush(ctx, callback);
         numScheduledFlushes++;
+        return flushOp;
     }
 
     @Override
-    public void scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
+    public ILSMIOOperation scheduleMerge(ILSMIndexOperationContext ctx, ILSMIOOperationCallback callback)
             throws HyracksDataException {
-        super.scheduleMerge(ctx, callback);
+        ILSMIOOperation mergeOp = super.scheduleMerge(ctx, callback);
         numScheduledMerges++;
+        return mergeOp;
     }
 
     @Override
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
index 1667e47..377ce05 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/org/apache/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
@@ -119,7 +119,7 @@
 
             case MERGE:
                 accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                        lsmBTree.getDiskComponents());
+                        lsmBTree.getDiskComponents(), null);
                 break;
 
             default:
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-common-test/src/test/java/org/apache/hyracks/storage/am/lsm/common/test/PrefixMergePolicyTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-common-test/src/test/java/org/apache/hyracks/storage/am/lsm/common/test/PrefixMergePolicyTest.java
index e521b4b..eaa0321 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-common-test/src/test/java/org/apache/hyracks/storage/am/lsm/common/test/PrefixMergePolicyTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-common-test/src/test/java/org/apache/hyracks/storage/am/lsm/common/test/PrefixMergePolicyTest.java
@@ -221,7 +221,7 @@
                 return null;
             }
         }).when(accessor).scheduleMerge(Mockito.any(ILSMIOOperationCallback.class),
-                Mockito.anyListOf(ILSMDiskComponent.class));
+                Mockito.anyListOf(ILSMDiskComponent.class), Mockito.any());
 
         Mockito.when(index.createAccessor(Mockito.any(IModificationOperationCallback.class),
                 Mockito.any(ISearchOperationCallback.class))).thenReturn(accessor);
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/LSMInvertedIndexMergeTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/LSMInvertedIndexMergeTest.java
index d093aac..fd744b0 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/LSMInvertedIndexMergeTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/LSMInvertedIndexMergeTest.java
@@ -58,7 +58,7 @@
             }
             // Perform merge.
             invIndexAccessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                    ((LSMInvertedIndex) invIndex).getDiskComponents());
+                    ((LSMInvertedIndex) invIndex).getDiskComponents(), null);
             validateAndCheckIndex(testCtx);
             runTinySearchWorkload(testCtx, tupleGen);
         }
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/PartitionedLSMInvertedIndexMergeTest.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/PartitionedLSMInvertedIndexMergeTest.java
index 3dc7262..cfca8f1 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/PartitionedLSMInvertedIndexMergeTest.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/PartitionedLSMInvertedIndexMergeTest.java
@@ -60,7 +60,7 @@
             }
             // Perform merge.
             invIndexAccessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                    ((LSMInvertedIndex) invIndex).getDiskComponents());
+                    ((LSMInvertedIndex) invIndex).getDiskComponents(), null);
             validateAndCheckIndex(testCtx);
             runTinySearchWorkload(testCtx, tupleGen);
         }
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/multithread/LSMInvertedIndexTestWorker.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/multithread/LSMInvertedIndexTestWorker.java
index 2345698..594e019 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/multithread/LSMInvertedIndexTestWorker.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-invertedindex-test/src/test/java/org/apache/hyracks/storage/am/lsm/invertedindex/multithread/LSMInvertedIndexTestWorker.java
@@ -116,7 +116,7 @@
 
             case MERGE: {
                 accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                        invIndex.getDiskComponents());
+                        invIndex.getDiskComponents(), null);
                 break;
             }
 
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTestDriver.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTestDriver.java
index 9209a3e..58c71dd 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTestDriver.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/LSMRTreeMergeTestDriver.java
@@ -78,7 +78,7 @@
 
             ILSMIndexAccessor accessor = (ILSMIndexAccessor) ctx.getIndexAccessor();
             accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                    ((AbstractLSMRTree) ctx.getIndex()).getDiskComponents());
+                    ((AbstractLSMRTree) ctx.getIndex()).getDiskComponents(), null);
 
             rTreeTestUtils.checkScan(ctx);
             rTreeTestUtils.checkDiskOrderScan(ctx);
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeTestWorker.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeTestWorker.java
index fe4870b..4630c28 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeTestWorker.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeTestWorker.java
@@ -79,7 +79,7 @@
 
             case MERGE:
                 accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                        lsmRTree.getDiskComponents());
+                        lsmRTree.getDiskComponents(), null);
                 break;
 
             default:
diff --git a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesTestWorker.java b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesTestWorker.java
index 2855f2e..bbada89 100644
--- a/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesTestWorker.java
+++ b/hyracks-fullstack/hyracks/hyracks-tests/hyracks-storage-am-lsm-rtree-test/src/test/java/org/apache/hyracks/storage/am/lsm/rtree/multithread/LSMRTreeWithAntiMatterTuplesTestWorker.java
@@ -68,7 +68,7 @@
 
             case MERGE:
                 accessor.scheduleMerge(NoOpIOOperationCallbackFactory.INSTANCE.createIoOpCallback(),
-                        ((AbstractLSMRTree) lsmRTree).getDiskComponents());
+                        ((AbstractLSMRTree) lsmRTree).getDiskComponents(), null);
                 break;
 
             default: