address Sattam's comments
diff --git a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
index b503c8b..ba9351f 100644
--- a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
+++ b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
@@ -26,7 +26,6 @@
 import edu.uci.ics.hyracks.storage.am.btree.api.IPrefixSlotManager;
 import edu.uci.ics.hyracks.storage.am.btree.compressors.FieldPrefixCompressor;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeOpContext.PageValidationInfo;
 import edu.uci.ics.hyracks.storage.am.btree.impls.FieldPrefixPrefixTupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.impls.FieldPrefixSlotManager;
@@ -37,6 +36,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleReference;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleWriter;
 import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.frames.FrameOpSpaceStatus;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.FindTupleMode;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.FindTupleNoExactMatchPolicy;
@@ -411,7 +411,7 @@
         int tupleIndex = slotManager.decodeSecondSlotField(slot);
         // Error indicator is set if there is no exact match.
         if (tupleIndex == slotManager.getErrorIndicator()) {
-            throw new BTreeNonExistentKeyException("Trying to update a tuple with a nonexistent key in leaf node.");
+            throw new TreeIndexNonExistentKeyException("Trying to update a tuple with a nonexistent key in leaf node.");
         }
         return slot;
     }
@@ -423,7 +423,7 @@
         int tupleIndex = slotManager.decodeSecondSlotField(slot);
         // Error indicator is set if there is no exact match.
         if (tupleIndex == slotManager.getErrorIndicator()) {
-            throw new BTreeNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
+            throw new TreeIndexNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
         }
         return slot;
     }
diff --git a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
index 1974989..3a4f156 100644
--- a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
+++ b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
@@ -21,13 +21,13 @@
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.api.IBTreeLeafFrame;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeOpContext.PageValidationInfo;
 import edu.uci.ics.hyracks.storage.am.common.api.ISplitKey;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrame;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleReference;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexTupleWriter;
 import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.frames.TreeIndexNSMFrame;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.FindTupleMode;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.FindTupleNoExactMatchPolicy;
@@ -83,7 +83,7 @@
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
         // Error indicator is set if there is no exact match.
         if (tupleIndex == slotManager.getErrorIndicator() || tupleIndex == slotManager.getGreatestKeyIndicator()) {
-            throw new BTreeNonExistentKeyException("Trying to update a tuple with a nonexistent key in leaf node.");
+            throw new TreeIndexNonExistentKeyException("Trying to update a tuple with a nonexistent key in leaf node.");
         }
         return tupleIndex;
     }
@@ -121,7 +121,7 @@
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
         // Error indicator is set if there is no exact match.
         if (tupleIndex == slotManager.getErrorIndicator() || tupleIndex == slotManager.getGreatestKeyIndicator()) {
-            throw new BTreeNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
+            throw new TreeIndexNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
         }
         return tupleIndex;
     }
diff --git a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
index 42e876c..67ee936 100644
--- a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
+++ b/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
@@ -33,7 +33,6 @@
 import edu.uci.ics.hyracks.storage.am.btree.api.IBTreeLeafFrame;
 import edu.uci.ics.hyracks.storage.am.btree.api.ITupleAcceptor;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNotUpdateableException;
 import edu.uci.ics.hyracks.storage.am.btree.frames.BTreeNSMInteriorFrame;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTreeOpContext.PageValidationInfo;
@@ -53,6 +52,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
 import edu.uci.ics.hyracks.storage.am.common.api.UnsortedInputException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.frames.FrameOpSpaceStatus;
 import edu.uci.ics.hyracks.storage.am.common.impls.AbstractTreeIndex;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
@@ -562,7 +562,7 @@
         // This means that there could be underflow, even an empty page that is
         // pointed to by an interior node.
         if (ctx.leafFrame.getTupleCount() == 0) {
-            throw new BTreeNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
+            throw new TreeIndexNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
         }
         int tupleIndex = ctx.leafFrame.findDeleteTupleIndex(tuple);
         ITupleReference beforeTuple = ctx.leafFrame.getMatchingKeyTuple(tuple, tupleIndex);
@@ -879,12 +879,8 @@
 
         @Override
         public void delete(ITupleReference tuple) throws HyracksDataException, TreeIndexException {
-            try {
-                ctx.setOperation(IndexOperation.DELETE);
-                btree.delete(tuple, ctx);
-            } catch (BTreeNonExistentKeyException e) {
-                //allow deletion of non-existing keys
-            }
+            ctx.setOperation(IndexOperation.DELETE);
+            btree.delete(tuple, ctx);
         }
 
         @Override
diff --git a/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/dataflow/IndexInsertUpdateDeleteOperatorNodePushable.java b/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/dataflow/IndexInsertUpdateDeleteOperatorNodePushable.java
index 4a9cfb4..8c5a789 100644
--- a/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/dataflow/IndexInsertUpdateDeleteOperatorNodePushable.java
+++ b/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/dataflow/IndexInsertUpdateDeleteOperatorNodePushable.java
@@ -30,6 +30,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ITupleFilter;
 import edu.uci.ics.hyracks.storage.am.common.api.ITupleFilterFactory;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.common.tuples.PermutingFrameTupleReference;
@@ -109,7 +110,11 @@
                         break;
                     }
                     case DELETE: {
-                        indexAccessor.delete(tuple);
+                        try {
+                            indexAccessor.delete(tuple);
+                        } catch (TreeIndexNonExistentKeyException e) {
+                            // ingnore that exception to allow deletions of non-existing keys
+                        }
                         break;
                     }
                     default: {
diff --git a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/exceptions/BTreeNonExistentKeyException.java b/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/exceptions/TreeIndexNonExistentKeyException.java
similarity index 61%
rename from hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/exceptions/BTreeNonExistentKeyException.java
rename to hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/exceptions/TreeIndexNonExistentKeyException.java
index 7237046..8b62063 100644
--- a/hyracks/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/exceptions/BTreeNonExistentKeyException.java
+++ b/hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/exceptions/TreeIndexNonExistentKeyException.java
@@ -13,17 +13,19 @@
  * limitations under the License.
  */
 
-package edu.uci.ics.hyracks.storage.am.btree.exceptions;
+package edu.uci.ics.hyracks.storage.am.common.exceptions;
 
-public class BTreeNonExistentKeyException extends BTreeException {
+import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
 
-    private static final long serialVersionUID = 1L;
+public class TreeIndexNonExistentKeyException extends TreeIndexException {
 
-    public BTreeNonExistentKeyException(Exception e) {
-        super(e);
-    }
+	private static final long serialVersionUID = 1L;
 
-    public BTreeNonExistentKeyException(String message) {
-        super(message);
-    }
+	public TreeIndexNonExistentKeyException(Exception e) {
+		super(e);
+	}
+
+	public TreeIndexNonExistentKeyException(String message) {
+		super(message);
+	}
 }
diff --git a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/inmemory/InMemoryInvertedIndex.java b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/inmemory/InMemoryInvertedIndex.java
index 222f4de..98e1f13 100644
--- a/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/inmemory/InMemoryInvertedIndex.java
+++ b/hyracks/hyracks-storage-am-lsm-invertedindex/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/invertedindex/inmemory/InMemoryInvertedIndex.java
@@ -21,7 +21,6 @@
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.frames.BTreeLeafFrameType;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree.BTreeAccessor;
@@ -33,6 +32,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.IVirtualBufferCache;
 import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedIndex;
@@ -134,7 +134,7 @@
             ITupleReference deleteTuple = ctx.tupleIter.getTuple();
             try {
                 btreeAccessor.delete(deleteTuple);
-            } catch (BTreeNonExistentKeyException e) {
+            } catch (TreeIndexNonExistentKeyException e) {
                 // Ignore this exception, since a document may have duplicate tokens.
             }
         }
diff --git a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
index e3e690b..cf45a36 100644
--- a/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
+++ b/hyracks/hyracks-storage-am-lsm-rtree/src/main/java/edu/uci/ics/hyracks/storage/am/lsm/rtree/impls/AbstractLSMRTree.java
@@ -24,7 +24,6 @@
 import edu.uci.ics.hyracks.api.io.FileReference;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree.BTreeAccessor;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
@@ -36,6 +35,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexFrameFactory;
 import edu.uci.ics.hyracks.storage.am.common.api.IVirtualFreePageManager;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.impls.NoOpOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.IndexOperation;
 import edu.uci.ics.hyracks.storage.am.lsm.common.api.ILSMComponent;
@@ -306,7 +306,7 @@
             if (foundTupleInMemoryBTree) {
                 try {
                     ctx.memBTreeAccessor.delete(tuple);
-                } catch (BTreeNonExistentKeyException e) {
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Tuple has been deleted in the meantime. Do nothing.
                     // This normally shouldn't happen if we are dealing with
                     // good citizens since LSMRTree is used as a secondary
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/btree/multithread/BTreeTestWorker.java b/hyracks/hyracks-tests/hyracks-storage-am-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/btree/multithread/BTreeTestWorker.java
index 262e21c..1946eb5 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/btree/multithread/BTreeTestWorker.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/btree/multithread/BTreeTestWorker.java
@@ -20,7 +20,6 @@
 import edu.uci.ics.hyracks.dataflow.common.comm.io.ArrayTupleReference;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNotUpdateableException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.BTree;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
@@ -31,6 +30,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.datagen.DataGenThread;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
 
 public class BTreeTestWorker extends AbstractIndexTestWorker {
@@ -74,7 +74,7 @@
                 deleteTuple.reset(deleteTb.getFieldEndOffsets(), deleteTb.getByteArray());
                 try {
                     accessor.delete(deleteTuple);
-                } catch (BTreeNonExistentKeyException e) {
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Ignore non-existant keys, since we get random tuples.
                 }
                 break;
@@ -82,7 +82,7 @@
             case UPDATE:
                 try {
                     accessor.update(tuple);
-                } catch (BTreeNonExistentKeyException e) {
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Ignore non-existant keys, since we get random tuples.
                 } catch (BTreeNotUpdateableException e) {
                     // Ignore not updateable exception due to numKeys == numFields.
diff --git a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
index 8a37b4e..6bbe756 100644
--- a/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
+++ b/hyracks/hyracks-tests/hyracks-storage-am-lsm-btree-test/src/test/java/edu/uci/ics/hyracks/storage/am/lsm/btree/multithread/LSMBTreeTestWorker.java
@@ -20,7 +20,6 @@
 import edu.uci.ics.hyracks.dataflow.common.comm.io.ArrayTupleReference;
 import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNotUpdateableException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
 import edu.uci.ics.hyracks.storage.am.common.AbstractIndexTestWorker;
@@ -30,6 +29,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.IndexException;
 import edu.uci.ics.hyracks.storage.am.common.datagen.DataGenThread;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
 import edu.uci.ics.hyracks.storage.am.lsm.btree.impls.LSMBTree;
 import edu.uci.ics.hyracks.storage.am.lsm.btree.impls.LSMBTree.LSMBTreeAccessor;
@@ -74,7 +74,7 @@
                 deleteTuple.reset(deleteTb.getFieldEndOffsets(), deleteTb.getByteArray());
                 try {
                     accessor.delete(deleteTuple);
-                } catch (BTreeNonExistentKeyException e) {
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Ignore non-existant keys, since we get random tuples.
                 }
                 break;
@@ -82,7 +82,7 @@
             case UPDATE:
                 try {
                     accessor.update(tuple);
-                } catch (BTreeNonExistentKeyException e) {
+                } catch (TreeIndexNonExistentKeyException e) {
                     // Ignore non-existant keys, since we get random tuples.
                 } catch (BTreeNotUpdateableException e) {
                     // Ignore not updateable exception due to numKeys == numFields.