diff --git a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
index 02ad3a1..0ad8b68 100644
--- a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
+++ b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeFieldPrefixNSMLeafFrame.java
@@ -31,7 +31,6 @@
 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.BTreeException;
 import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeNonExistentKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.FieldPrefixPrefixTupleReference;
 import edu.uci.ics.hyracks.storage.am.btree.impls.FieldPrefixSlotManager;
diff --git a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMInteriorFrame.java b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMInteriorFrame.java
index aaf9845..93b7ea7 100644
--- a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMInteriorFrame.java
+++ b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMInteriorFrame.java
@@ -82,23 +82,8 @@
     @Override
     public int findInsertTupleIndex(ITupleReference tuple, MultiComparator cmp) throws TreeIndexException {
         frameTuple.setFieldCount(cmp.getKeyFieldCount());
-        int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.INCLUSIVE,
+        return slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.INCLUSIVE,
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
-        int slotOff = slotManager.getSlotOff(tupleIndex);
-        boolean isDuplicate = true;
-
-        // TODO: We may not need to check for duplicates in interior nodes.
-        if (tupleIndex < 0)
-            isDuplicate = false; // greater than all existing keys
-        else {
-            frameTuple.resetByTupleOffset(buf, slotManager.getTupleOff(slotOff));
-            if (cmp.compare(tuple, frameTuple) != 0)
-                isDuplicate = false;
-        }
-        if (isDuplicate) {
-            throw new BTreeNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
-        }
-        return tupleIndex;
     }
     
     @Override
@@ -303,7 +288,7 @@
         int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, targetCmp, fsm,
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
         int slotOff = slotManager.getSlotOff(tupleIndex);
-        if (tupleIndex < 0) {
+        if (slotManager.isHighestTupleIndex(tupleIndex)) {
             return buf.getInt(rightLeafOff);
         } else {
             int origTupleOff = slotManager.getTupleOff(slotOff);
@@ -342,13 +327,10 @@
     @Override
     public void delete(ITupleReference tuple, MultiComparator cmp, int tupleIndex) {
         frameTuple.setFieldCount(cmp.getKeyFieldCount());
-        //int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.INCLUSIVE,
-        //        FindTupleNoExactMatchPolicy.FTP_HIGHER_KEY);
         int slotOff = slotManager.getSlotOff(tupleIndex);
         int tupleOff;
         int keySize;
-
-        if (tupleIndex < 0) {
+        if (slotManager.isHighestTupleIndex(tupleIndex)) {
             tupleOff = slotManager.getTupleOff(slotManager.getSlotEndOff());
             frameTuple.resetByTupleOffset(buf, tupleOff);
             keySize = tupleWriter.bytesRequired(frameTuple, 0, cmp.getKeyFieldCount());
diff --git a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
index 02adb01..9b75843 100644
--- a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
+++ b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/BTreeNSMLeafFrame.java
@@ -70,22 +70,10 @@
     @Override
     public int findInsertTupleIndex(ITupleReference tuple, MultiComparator cmp) throws TreeIndexException {
         frameTuple.setFieldCount(cmp.getFieldCount());
-        int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.INCLUSIVE,
+        int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.EXCLUSIVE_ERROR_IF_EXISTS,
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
-        int slotOff = slotManager.getSlotOff(tupleIndex);
-        // TODO: Push this check into findSlot, and distinguish between greatest slot and errors.
-        boolean isDuplicate = true;
-        if (tupleIndex < 0) {
-            // Greater than all existing keys.
-            isDuplicate = false;
-        }
-        else {
-            frameTuple.resetByTupleOffset(buf, slotManager.getTupleOff(slotOff));
-            if (cmp.compare(tuple, frameTuple) != 0) {
-                isDuplicate = false;
-            }
-        }
-        if (isDuplicate) {
+        // Error indicator is set if there is an exact match.
+        if (slotManager.isErrorTupleIndex(tupleIndex)) {
             throw new BTreeDuplicateKeyException("Trying to insert duplicate key into leaf node.");
         }
         return tupleIndex;
@@ -96,8 +84,8 @@
         frameTuple.setFieldCount(cmp.getFieldCount());
         int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.EXACT,
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
-        // TODO: Push this check into findSlot, and distinguish between greatest slot and errors.
-        if (tupleIndex < 0) {
+        // Error indicator is set if there is no exact match.
+        if (slotManager.isErrorTupleIndex(tupleIndex)) {
             throw new BTreeNonExistentKeyException("Trying to update a tuple with a nonexistent key in leaf node.");
         }        
         return tupleIndex;
@@ -108,8 +96,8 @@
         frameTuple.setFieldCount(cmp.getFieldCount());
         int tupleIndex = slotManager.findTupleIndex(tuple, frameTuple, cmp, FindTupleMode.EXACT,
                 FindTupleNoExactMatchPolicy.HIGHER_KEY);
-        // TODO: Push this check into findSlot, and distinguish between greatest slot and errors.
-        if (tupleIndex < 0) {
+        // Error indicator is set if there is no exact match.
+        if (slotManager.isErrorTupleIndex(tupleIndex)) {
             throw new BTreeNonExistentKeyException("Trying to delete a tuple with a nonexistent key in leaf node.");
         }        
         return tupleIndex;
diff --git a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/OrderedSlotManager.java b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/OrderedSlotManager.java
index 1f62f30..4a07fa4 100644
--- a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/OrderedSlotManager.java
+++ b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/frames/OrderedSlotManager.java
@@ -24,11 +24,15 @@
 
 public class OrderedSlotManager extends AbstractSlotManager {
     
+    private final int HIGHEST_TUPLE_INDEX = -1;
+    private final int ERROR_TUPLE_INDEX = -2;
+    
 	@Override
     public int findTupleIndex(ITupleReference searchKey, ITreeIndexTupleReference frameTuple, MultiComparator multiCmp,
             FindTupleMode mode, FindTupleNoExactMatchPolicy matchPolicy) {
-        if (frame.getTupleCount() <= 0)
+        if (frame.getTupleCount() <= 0) {
             return -1;
+        }
 
         int mid;
         int begin = 0;
@@ -45,42 +49,52 @@
                 begin = mid + 1;
             } else {
                 if (mode == FindTupleMode.EXCLUSIVE) {
-                    if (matchPolicy == FindTupleNoExactMatchPolicy.HIGHER_KEY)
+                    if (matchPolicy == FindTupleNoExactMatchPolicy.HIGHER_KEY) {
                         begin = mid + 1;
-                    else
+                    } else {
                         end = mid - 1;
+                    }
                 } else {
-                    return mid;
+                    if (mode == FindTupleMode.EXCLUSIVE_ERROR_IF_EXISTS) {
+                        return ERROR_TUPLE_INDEX;
+                    } else {
+                        return mid;
+                    }
                 }
             }
         }
 
-        if (mode == FindTupleMode.EXACT)
-            return -1;
+        if (mode == FindTupleMode.EXACT) {
+            return ERROR_TUPLE_INDEX;
+        }
 
         if (matchPolicy == FindTupleNoExactMatchPolicy.HIGHER_KEY) {
-            if (begin > frame.getTupleCount() - 1)
-                return -1;
+            if (begin > frame.getTupleCount() - 1) {
+                return HIGHEST_TUPLE_INDEX;
+            }
             frameTuple.resetByTupleIndex(frame, begin);
-            if (multiCmp.compare(searchKey, frameTuple) < 0)
+            if (multiCmp.compare(searchKey, frameTuple) < 0) {
                 return begin;
-            else
-                return -1;
+            } else {
+                return HIGHEST_TUPLE_INDEX;
+            }
         } else {
-            if (end < 0)
-                return -1;
+            if (end < 0) {
+                return HIGHEST_TUPLE_INDEX;
+            }
             frameTuple.resetByTupleIndex(frame, end);
-            if (multiCmp.compare(searchKey, frameTuple) > 0)
+            if (multiCmp.compare(searchKey, frameTuple) > 0) {
                 return end;
-            else
-                return -1;
+            } else {
+                return HIGHEST_TUPLE_INDEX;
+            }
         }
     }
     
     @Override
     public int insertSlot(int tupleIndex, int tupleOff) {
         int slotOff = getSlotOff(tupleIndex);
-        if (tupleIndex < 0) {
+        if (tupleIndex == HIGHEST_TUPLE_INDEX) {
             slotOff = getSlotEndOff() - slotSize;
             setSlot(slotOff, tupleOff);
             return slotOff;
@@ -93,4 +107,14 @@
             return slotOff;
         }
     }
+
+    @Override
+    public boolean isHighestTupleIndex(int tupleIndex) {
+        return tupleIndex == HIGHEST_TUPLE_INDEX;
+    }
+
+    @Override
+    public boolean isErrorTupleIndex(int tupleIndex) {
+        return tupleIndex == ERROR_TUPLE_INDEX;
+    }
 }
diff --git a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
index 0d3c35e..9a47d7b 100644
--- a/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
+++ b/hyracks-storage-am-btree/src/main/java/edu/uci/ics/hyracks/storage/am/btree/impls/BTree.java
@@ -125,12 +125,18 @@
 
         ICachedPage page = bufferCache.pin(BufferedFileHandle.getDiskPageId(fileId, currentPageId), false);
         page.acquireReadLatch();
-        cursor.setBufferCache(bufferCache);
-        cursor.setFileId(fileId);
-        cursor.setCurrentPageId(currentPageId);
-        cursor.setMaxPageId(maxPageId);
-        ctx.cursorInitialState.setPage(page);
-        cursor.open(ctx.cursorInitialState, diskOrderScanPredicate);
+        try {
+            cursor.setBufferCache(bufferCache);
+            cursor.setFileId(fileId);
+            cursor.setCurrentPageId(currentPageId);
+            cursor.setMaxPageId(maxPageId);
+            ctx.cursorInitialState.setPage(page);
+            cursor.open(ctx.cursorInitialState, diskOrderScanPredicate);
+        } catch (Exception e) {
+            page.releaseReadLatch();
+            bufferCache.unpin(page);
+            throw new HyracksDataException(e);
+        }
     }
 
     public void search(ITreeIndexCursor cursor, RangePredicate pred, BTreeOpContext ctx) throws Exception {
diff --git a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/api/ISlotManager.java b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/api/ISlotManager.java
index a6102ab..93f3cf0 100644
--- a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/api/ISlotManager.java
+++ b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/api/ISlotManager.java
@@ -27,6 +27,10 @@
 			ITreeIndexTupleReference frameTuple, MultiComparator multiCmp,
 			FindTupleMode mode, FindTupleNoExactMatchPolicy matchPolicy);
 
+	public boolean isHighestTupleIndex(int tupleIndex);
+	
+	public boolean isErrorTupleIndex(int tupleIndex);
+	
 	public int insertSlot(int tupleIndex, int tupleOff);
 
 	public int getSlotStartOff();
diff --git a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/frames/TreeIndexNSMFrame.java b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/frames/TreeIndexNSMFrame.java
index bec3418..e9f5ebc 100644
--- a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/frames/TreeIndexNSMFrame.java
+++ b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/frames/TreeIndexNSMFrame.java
@@ -29,9 +29,6 @@
 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.ophelpers.FindTupleMode;
-import edu.uci.ics.hyracks.storage.am.common.ophelpers.FindTupleNoExactMatchPolicy;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.MultiComparator;
 import edu.uci.ics.hyracks.storage.am.common.ophelpers.SlotOffTupleOff;
 import edu.uci.ics.hyracks.storage.common.buffercache.ICachedPage;
diff --git a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/impls/TreeDiskOrderScanCursor.java b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/impls/TreeDiskOrderScanCursor.java
index e1a0dd6..c3c256e 100644
--- a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/impls/TreeDiskOrderScanCursor.java
+++ b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/impls/TreeDiskOrderScanCursor.java
@@ -15,9 +15,7 @@
 
 package edu.uci.ics.hyracks.storage.am.common.impls;
 
-import edu.uci.ics.hyracks.api.dataflow.value.ISerializerDeserializer;
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
-import edu.uci.ics.hyracks.dataflow.common.data.marshalling.IntegerSerializerDeserializer;
 import edu.uci.ics.hyracks.storage.am.common.api.ICursorInitialState;
 import edu.uci.ics.hyracks.storage.am.common.api.ISearchPredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
diff --git a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/ophelpers/FindTupleMode.java b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/ophelpers/FindTupleMode.java
index 11ac257..5002189 100644
--- a/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/ophelpers/FindTupleMode.java
+++ b/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/ophelpers/FindTupleMode.java
@@ -16,5 +16,5 @@
 package edu.uci.ics.hyracks.storage.am.common.ophelpers;
 
 public enum FindTupleMode {
-	FTM_INCLUSIVE, FTM_EXCLUSIVE, FTM_EXACT
+	INCLUSIVE, EXCLUSIVE, EXCLUSIVE_ERROR_IF_EXISTS, EXACT
 }