diff --git a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
index 18a81e5..76b3a22 100644
--- a/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
+++ b/asterix-app/src/main/java/edu/uci/ics/asterix/api/common/AsterixAppRuntimeContext.java
@@ -29,6 +29,7 @@
 import edu.uci.ics.asterix.common.context.AsterixFileMapManager;
 import edu.uci.ics.asterix.common.context.ConstantMergePolicy;
 import edu.uci.ics.asterix.common.context.DatasetLifecycleManager;
+import edu.uci.ics.asterix.common.context.PrefixMergePolicy;
 import edu.uci.ics.asterix.common.exceptions.ACIDException;
 import edu.uci.ics.asterix.common.exceptions.AsterixException;
 import edu.uci.ics.asterix.common.transactions.IAsterixAppRuntimeContextProvider;
@@ -110,7 +111,7 @@
 
         AsynchronousScheduler.INSTANCE.init(ncApplicationContext.getThreadFactory());
         lsmIOScheduler = AsynchronousScheduler.INSTANCE;
-        mergePolicy = new ConstantMergePolicy(storageProperties.getLSMIndexMergeThreshold(), this);
+        mergePolicy = new PrefixMergePolicy(10485760, 5, this);//new ConstantMergePolicy(storageProperties.getLSMIndexMergeThreshold(), this);
 
         ILocalResourceRepositoryFactory persistentLocalResourceRepositoryFactory = new PersistentLocalResourceRepositoryFactory(
                 ioManager);
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
index cf69bfe..4e1239f 100644
--- a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/ConstantMergePolicy.java
@@ -15,6 +15,7 @@
 
 package edu.uci.ics.asterix.common.context;
 
+import java.util.ArrayList;
 import java.util.List;
 
 import edu.uci.ics.asterix.common.api.IAsterixAppRuntimeContext;
@@ -39,11 +40,11 @@
 
     @Override
     public void diskComponentAdded(final ILSMIndex index) throws HyracksDataException, IndexException {
-        List<ILSMComponent> immutableComponents = index.getImmutableComponents();
+        List<ILSMComponent> immutableComponents = new ArrayList<ILSMComponent>(index.getImmutableComponents());
         if (!ctx.isShuttingdown() && immutableComponents.size() >= threshold) {
             ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(NoOpOperationCallback.INSTANCE,
                     NoOpOperationCallback.INSTANCE);
-            accessor.scheduleMerge(NoOpIOOperationCallback.INSTANCE);
+            accessor.scheduleMerge(NoOpIOOperationCallback.INSTANCE, immutableComponents);
         }
     }
 }
diff --git a/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrefixMergePolicy.java b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrefixMergePolicy.java
new file mode 100644
index 0000000..d975c2a
--- /dev/null
+++ b/asterix-common/src/main/java/edu/uci/ics/asterix/common/context/PrefixMergePolicy.java
@@ -0,0 +1,78 @@
+/*
+ * Copyright 2009-2013 by The Regents of the University of California
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * you may obtain a copy of the License from
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package edu.uci.ics.asterix.common.context;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import edu.uci.ics.asterix.common.api.IAsterixAppRuntimeContext;
+import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
+import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndex;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMIndexAccessor;
+import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMMergePolicy;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.AbstractDiskLSMComponent;
+import edu.uci.ics.hyracks.storage.am.lsm.common.impls.NoOpIOOperationCallback;
+
+public class PrefixMergePolicy implements ILSMMergePolicy {
+
+    private final long maxMergableComponentSize;
+    private final int maxTolernaceComponentCount;
+    private final IAsterixAppRuntimeContext ctx;
+
+    public PrefixMergePolicy(long maxMergableComponentSize, int maxTolernaceComponentCount,
+            IAsterixAppRuntimeContext ctx) {
+        this.maxMergableComponentSize = maxMergableComponentSize;
+        this.maxTolernaceComponentCount = maxTolernaceComponentCount;
+        this.ctx = ctx;
+    }
+
+    @Override
+    public void diskComponentAdded(final ILSMIndex index) throws HyracksDataException, IndexException {
+        if (!ctx.isShuttingdown()) {
+            // 1.  Look at the candidate components for merging in oldest-first order.  If one exists, identify the prefix of the sequence of
+            // all such components for which the sum of their sizes exceeds MaxMrgCompSz.  Schedule a merge of those components into a new component.
+            // 2.  If a merge from 1 doesn't happen, see if the set of candidate components for merging exceeds MaxTolCompCnt.  If so, schedule
+            // a merge all of the current candidates into a new single component.
+            List<ILSMComponent> immutableComponents = new ArrayList<ILSMComponent>(index.getImmutableComponents());
+            long totalSize = 0;
+            int startIndex = -1;
+            for (int i = 0; i < immutableComponents.size(); i++) {
+                ILSMComponent c = immutableComponents.get(i);
+                long componentSize = ((AbstractDiskLSMComponent) c).getComponentSize();
+                if (componentSize > maxMergableComponentSize) {
+                    startIndex = i;
+                    continue;
+                }
+                totalSize += componentSize;
+                boolean isLastComponent = i + 1 == immutableComponents.size() ? true : false;
+                if (totalSize > maxMergableComponentSize
+                        || (isLastComponent && i - startIndex >= maxTolernaceComponentCount)) {
+                    List<ILSMComponent> mergableCopments = new ArrayList<ILSMComponent>();
+                    for (int j = startIndex + 1; j <= i; j++) {
+                        mergableCopments.add(immutableComponents.get(j));
+                    }
+                    ILSMIndexAccessor accessor = (ILSMIndexAccessor) index.createAccessor(
+                            NoOpOperationCallback.INSTANCE, NoOpOperationCallback.INSTANCE);
+                    accessor.scheduleMerge(NoOpIOOperationCallback.INSTANCE, mergableCopments);
+                    break;
+                }
+            }
+        }
+    }
+}