diff --git a/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/comparators/ListItemBinaryComparatorFactory.java b/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/comparators/ListItemBinaryComparatorFactory.java
index 379a7e3..01e34b0 100644
--- a/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/comparators/ListItemBinaryComparatorFactory.java
+++ b/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/comparators/ListItemBinaryComparatorFactory.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright 2009-2010 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.dataflow.data.nontagged.comparators;
 
 import edu.uci.ics.asterix.formats.nontagged.UTF8StringLowercasePointable;
diff --git a/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/hash/ListItemBinaryHashFunctionFactory.java b/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/hash/ListItemBinaryHashFunctionFactory.java
index 1c0773c..67878a3 100644
--- a/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/hash/ListItemBinaryHashFunctionFactory.java
+++ b/asterix-om/src/main/java/edu/uci/ics/asterix/dataflow/data/nontagged/hash/ListItemBinaryHashFunctionFactory.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright 2009-2010 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.dataflow.data.nontagged.hash;
 
 import edu.uci.ics.asterix.formats.nontagged.UTF8StringLowercasePointable;
@@ -7,10 +22,13 @@
 import edu.uci.ics.hyracks.api.dataflow.value.IBinaryHashFunctionFactory;
 import edu.uci.ics.hyracks.data.std.accessors.MurmurHash3BinaryHashFunctionFamily;
 import edu.uci.ics.hyracks.data.std.accessors.PointableBinaryHashFunctionFactory;
-import edu.uci.ics.hyracks.data.std.primitive.FloatPointable;
-import edu.uci.ics.hyracks.data.std.primitive.IntegerPointable;
-import edu.uci.ics.hyracks.data.std.primitive.UTF8StringPointable;
 
+/**
+ * This hash function factory is introduced to be able to hash heterogeneous list items.
+ * The item type tag is also included in the hash computation to distinguish the different 
+ * types with the same raw bytes.
+ * 
+ */
 public class ListItemBinaryHashFunctionFactory implements IBinaryHashFunctionFactory {
 
     private static final long serialVersionUID = 1L;
@@ -27,19 +45,9 @@
     
     public IBinaryHashFunction createBinaryHashFunction(final ATypeTag itemTypeTag, final boolean ignoreCase) {
         return new IBinaryHashFunction() {
-
-            private IBinaryHashFunction boolHash = BooleanBinaryHashFunctionFactory.INSTANCE.createBinaryHashFunction();
-            private IBinaryHashFunction intHash = new PointableBinaryHashFunctionFactory(IntegerPointable.FACTORY)
-                    .createBinaryHashFunction();
-            private IBinaryHashFunction longHash = LongBinaryHashFunctionFactory.INSTANCE.createBinaryHashFunction();
-            private IBinaryHashFunction floatHash = new PointableBinaryHashFunctionFactory(FloatPointable.FACTORY)
-                    .createBinaryHashFunction();
-            private IBinaryHashFunction stringHash = new PointableBinaryHashFunctionFactory(UTF8StringPointable.FACTORY)
-                    .createBinaryHashFunction();
+        	
             private IBinaryHashFunction lowerCaseStringHash = new PointableBinaryHashFunctionFactory(UTF8StringLowercasePointable.FACTORY)
             		.createBinaryHashFunction();
-            private IBinaryHashFunction doubleHash = DoubleBinaryHashFunctionFactory.INSTANCE
-                    .createBinaryHashFunction();
             private IBinaryHashFunction genericBinaryHash = MurmurHash3BinaryHashFunctionFamily.INSTANCE
                     .createBinaryHashFunction(0);
 
@@ -52,38 +60,21 @@
             		skip = 1;
             	}
                 switch (tag) {
-                    case BOOLEAN: {
-                        return boolHash.hash(bytes, offset + skip, length - skip);
-                    }
-                    case TIME:
-                    case DATE:
-                    case YEARMONTHDURATION:
-                    case INT32: {
-                        return intHash.hash(bytes, offset + skip, length - skip);
-                    }
-                    case DATETIME:
-                    case DAYTIMEDURATION:
-                    case INT64: {
-                        return longHash.hash(bytes, offset + skip, length - skip);
-                    }
-                    case FLOAT: {
-                        return floatHash.hash(bytes, offset + skip, length - skip);
-                    }
-                    case DOUBLE: {
-                        return doubleHash.hash(bytes, offset + skip, length - skip);
-                    }
                     case STRING: {
                     	if (ignoreCase) {
                     		return lowerCaseStringHash.hash(bytes, offset + skip, length - skip);
-                    	} else {
-                    		return stringHash.hash(bytes, offset + skip, length - skip);
                     	}
                     }
-                    case NULL: {
-                        return 0;
-                    }
                     default: {
-                        return genericBinaryHash.hash(bytes, offset + skip, length - skip);
+                    	if (itemTypeTag != ATypeTag.ANY) {
+                    		// add the type tag
+                    		byte[] taggedBytes = new byte[length + 1];
+                    		taggedBytes[0] = itemTypeTag.serialize();
+                    		System.arraycopy(bytes, offset, taggedBytes, 1, length);
+                    		return genericBinaryHash.hash(taggedBytes, 0, length + 1);
+                    	} else {
+                    		return genericBinaryHash.hash(bytes, offset, length);
+                    	}
                     }
                 }
             }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AbstractAsterixListIterator.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AbstractAsterixListIterator.java
index 84eef1d..2f9cfc7 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AbstractAsterixListIterator.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AbstractAsterixListIterator.java
@@ -15,7 +15,8 @@
     protected int pos = -1;
     protected int nextPos = -1;
     protected int itemLen = -1;
-    protected int size = -1;
+    protected int numberOfItems = -1;
+    protected int listLength = -1;
     protected int startOff = -1;
     protected IBinaryComparator cmp;
 
@@ -29,12 +30,12 @@
 
     @Override
     public boolean hasNext() {
-        return count < size;
+        return count < numberOfItems;
     }
 
     @Override
     public int size() {
-        return size;
+        return numberOfItems;
     }
 
     @Override
@@ -56,8 +57,8 @@
         try {
         	pos = nextPos;
         	++count;
-            nextPos = data.length;
-            if (count + 1 < size) {
+            nextPos = startOff + listLength;
+            if (count + 1 < numberOfItems) {
             	nextPos = getItemOffset(data, startOff, count + 1);
             }
             itemLen = nextPos - pos;
@@ -71,8 +72,8 @@
         count = 0;
         try {
             pos = getItemOffset(data, startOff, count);
-            nextPos = data.length;
-            if (count + 1 < size) {
+            nextPos = startOff + listLength;
+            if (count + 1 < numberOfItems) {
             	nextPos = getItemOffset(data, startOff, count + 1);
             }
             itemLen = nextPos - pos;
@@ -84,7 +85,8 @@
     public void reset(byte[] data, int startOff) {
         this.data = data;
         this.startOff = startOff;
-        size = getNumberOfItems(data, startOff);
+        this.numberOfItems = getNumberOfItems(data, startOff);
+        this.listLength = getListLength(data, startOff);
         ATypeTag tag = EnumDeserializer.ATYPETAGDESERIALIZER.deserialize(data[startOff + 1]);
         switch (tag) {
             case INT32: {
@@ -119,4 +121,6 @@
     protected abstract int getItemOffset(byte[] serOrderedList, int offset, int itemIndex) throws AsterixException;
 
     protected abstract int getNumberOfItems(byte[] serOrderedList, int offset);
+    
+    protected abstract int getListLength(byte[] serOrderedList, int offset);
 }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixOrderedListIterator.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixOrderedListIterator.java
index d3714c1..6a73b6d 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixOrderedListIterator.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixOrderedListIterator.java
@@ -14,4 +14,9 @@
     protected int getNumberOfItems(byte[] serOrderedList, int offset) {
         return AOrderedListSerializerDeserializer.getNumberOfItems(serOrderedList, offset);
     }
+
+	@Override
+	protected int getListLength(byte[] serOrderedList, int offset) {
+		return AOrderedListSerializerDeserializer.getOrderedListLength(serOrderedList, offset + 1);
+	}
 }
diff --git a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixUnorderedListIterator.java b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixUnorderedListIterator.java
index de7742b..90d9ae3 100644
--- a/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixUnorderedListIterator.java
+++ b/asterix-runtime/src/main/java/edu/uci/ics/asterix/runtime/evaluators/common/AsterixUnorderedListIterator.java
@@ -14,4 +14,9 @@
     protected int getNumberOfItems(byte[] serOrderedList, int offset) {
         return AUnorderedListSerializerDeserializer.getNumberOfItems(serOrderedList, offset);
     }
+
+	@Override
+	protected int getListLength(byte[] serOrderedList, int offset) {
+		return AUnorderedListSerializerDeserializer.getUnorderedListLength(serOrderedList, offset + 1);
+	}
 }