diff --git a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
index 70ed7ef..a24a459 100644
--- a/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
+++ b/asterix-algebra/src/main/java/edu/uci/ics/asterix/optimizer/base/RuleCollections.java
@@ -63,6 +63,7 @@
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.ComplexUnnestToProductRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.ConsolidateAssignsRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.ConsolidateSelectsRule;
+import edu.uci.ics.hyracks.algebricks.rewriter.rules.EliminateGroupByEmptyKeyRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.EliminateSubplanRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.EnforceOrderByAfterSubplan;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.EnforceStructuralPropertiesRule;
@@ -82,6 +83,7 @@
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.IntroduceGroupByForSubplanRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.IntroduceProjectsRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.IsolateHyracksOperatorsRule;
+import edu.uci.ics.hyracks.algebricks.rewriter.rules.LeftOuterJoinToInnerJoinRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.PullSelectOutOfEqJoin;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.PushAssignBelowUnionAllRule;
 import edu.uci.ics.hyracks.algebricks.rewriter.rules.PushAssignDownThroughProductRule;
@@ -162,6 +164,8 @@
         condPushDownAndJoinInference.add(new PushProperJoinThroughProduct());
         condPushDownAndJoinInference.add(new PushGroupByThroughProduct());
         condPushDownAndJoinInference.add(new NestGroupByRule());
+        condPushDownAndJoinInference.add(new EliminateGroupByEmptyKeyRule());
+        condPushDownAndJoinInference.add(new LeftOuterJoinToInnerJoinRule());
 
         return condPushDownAndJoinInference;
     }
diff --git a/asterix-app/src/test/resources/optimizerts/queries/q08_group_by.aql b/asterix-app/src/test/resources/optimizerts/queries/q08_group_by.aql
new file mode 100644
index 0000000..96b20a4
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/q08_group_by.aql
@@ -0,0 +1,149 @@
+drop dataverse q08_group_by if exists;
+
+create dataverse q08_group_by;
+
+use dataverse q08_group_by;
+
+create type LineItemType as closed {
+  l_orderkey: int32, 
+  l_partkey: int32, 
+  l_suppkey: int32, 
+  l_linenumber: int32, 
+  l_quantity: double, 
+  l_extendedprice: double,
+  l_discount: double, 
+  l_tax: double,
+  l_returnflag: string, 
+  l_linestatus: string, 
+  l_shipdate: string,
+  l_commitdate: string, 
+  l_receiptdate: string, 
+  l_shipinstruct: string, 
+  l_shipmode: string, 
+  l_comment: string
+}
+
+create type OrderType as closed {
+  o_orderkey: int32, 
+  o_custkey: int32, 
+  o_orderstatus: string, 
+  o_totalprice: double, 
+  o_orderdate: string, 
+  o_orderpriority: string,
+  o_clerk: string, 
+  o_shippriority: int32, 
+  o_comment: string
+}
+
+create type CustomerType as closed {
+  c_custkey: int32, 
+  c_name: string, 
+  c_address: string, 
+  c_nationkey: int32, 
+  c_phone: string, 
+  c_acctbal: double, 
+  c_mktsegment: string,
+  c_comment: string
+}
+
+create type SupplierType as closed {
+  s_suppkey: int32, 
+  s_name: string,
+  s_address: string,
+  s_nationkey: int32,
+  s_phone: string,
+  s_acctbal: double,
+  s_comment: string
+}
+
+create type NationType as closed {
+  n_nationkey: int32,
+  n_name: string,
+  n_regionkey: int32,
+  n_comment: string
+}
+
+create type RegionType as closed {
+  r_regionkey: int32,
+  r_name: string,
+  r_comment: string
+}
+
+create type PartType as closed {
+  p_partkey: int32, 
+  p_name: string, 
+  p_mfgr: string,
+  p_brand: string,
+  p_type: string,
+  p_size: int32,
+  p_container: string,
+  p_retailprice: double,
+  p_comment: string
+}
+
+create dataset LineItem(LineItemType)
+  primary key l_orderkey, l_linenumber;
+create dataset Orders(OrderType)
+  primary key o_orderkey;
+create dataset Customer(CustomerType) 
+  primary key c_custkey;
+create dataset Supplier(SupplierType)
+  primary key s_suppkey;
+create dataset Nation(NationType) 
+  primary key n_nationkey;
+create dataset Region(RegionType)
+  primary key r_regionkey;
+create dataset Part(PartType)
+  primary key p_partkey;
+
+for $s in dataset("Supplier")
+    for $lnrcop in (
+      for $lnrco in (
+        for $l in dataset('LineItem')
+        for $nrco in (
+          for $o in dataset('Orders')
+          for $nrc in (
+            for $c in dataset('Customer')
+            for $nr in (
+              for $n1 in dataset('Nation')
+              for $r1 in dataset('Region')
+              where $n1.n_regionkey = $r1.r_regionkey and $r1.r_name = 'AMERICA'
+              return { "n_nationkey": $n1.n_nationkey }
+            )
+            where $c.c_nationkey = $nr.n_nationkey
+            return { "c_custkey": $c.c_custkey }
+          )
+          where $nrc.c_custkey = $o.o_custkey
+          return {
+            "o_orderdate" : $o.o_orderdate, 
+            "o_orderkey": $o.o_orderkey 
+          }
+        )
+        where $l.l_orderkey = $nrco.o_orderkey
+          and $nrco.o_orderdate >= '1995-01-01' 
+          and $nrco.o_orderdate <= '1996-12-31'
+        return {
+          "o_orderdate": $nrco.o_orderdate, 
+          "l_partkey": $l.l_partkey, 
+          "l_discount": $l.l_discount, 
+          "l_extendedprice": $l.l_extendedprice, 
+          "l_suppkey": $l.l_suppkey
+        }
+      )
+      for $p in dataset("Part")
+      where $p.p_partkey = $lnrco.l_partkey and $p.p_type = 'ECONOMY ANODIZED STEEL'
+      return {
+        "o_orderdate": $lnrco.o_orderdate, 
+        "l_discount": $lnrco.l_discount, 
+        "l_extendedprice": $lnrco.l_extendedprice, 
+        "l_suppkey": $lnrco.l_suppkey 
+      }
+    )
+    where $s.s_suppkey = $lnrcop.l_suppkey
+    return {
+      "o_orderdate": $lnrcop.o_orderdate, 
+      "l_discount": $lnrcop.l_discount, 
+      "l_extendedprice": $lnrcop.l_extendedprice, 
+      "l_suppkey": $lnrcop.l_suppkey, 
+      "s_nationkey": $s.s_nationkey
+    }
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/optimizerts/queries/q09_group_by.aql b/asterix-app/src/test/resources/optimizerts/queries/q09_group_by.aql
new file mode 100644
index 0000000..3c9dc47
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/q09_group_by.aql
@@ -0,0 +1,153 @@
+drop dataverse q09_group_by if exists;
+
+create dataverse q09_group_by;
+
+use dataverse q09_group_by;
+
+create type LineItemType as closed {
+  l_orderkey: int32, 
+  l_partkey: int32, 
+  l_suppkey: int32, 
+  l_linenumber: int32, 
+  l_quantity: int32, 
+  l_extendedprice: double,
+  l_discount: double, 
+  l_tax: double,
+  l_returnflag: string, 
+  l_linestatus: string, 
+  l_shipdate: string,
+  l_commitdate: string, 
+  l_receiptdate: string, 
+  l_shipinstruct: string, 
+  l_shipmode: string, 
+  l_comment: string
+}
+
+create type OrderType as closed {
+  o_orderkey: int32, 
+  o_custkey: int32, 
+  o_orderstatus: string, 
+  o_totalprice: double, 
+  o_orderdate: string, 
+  o_orderpriority: string,
+  o_clerk: string, 
+  o_shippriority: int32, 
+  o_comment: string
+}
+
+create type CustomerType as closed {
+  c_custkey: int32, 
+  c_name: string, 
+  c_address: string, 
+  c_nationkey: int32, 
+  c_phone: string, 
+  c_acctbal: double, 
+  c_mktsegment: string,
+  c_comment: string
+}
+
+create type SupplierType as closed {
+  s_suppkey: int32, 
+  s_name: string,
+  s_address: string,
+  s_nationkey: int32,
+  s_phone: string,
+  s_acctbal: double,
+  s_comment: string
+}
+
+create type NationType as closed {
+  n_nationkey: int32,
+  n_name: string,
+  n_regionkey: int32,
+  n_comment: string
+}
+
+create type RegionType as closed {
+	r_regionkey: int32, 
+	r_name: string, 
+	r_comment: string
+} 
+
+create type PartType as closed {
+  p_partkey: int32, 
+  p_name: string, 
+  p_mfgr: string,
+  p_brand: string,
+  p_type: string,
+  p_size: int32,
+  p_container: string,
+  p_retailprice: double,
+  p_comment: string
+}
+
+create type PartSuppType as closed {
+  ps_partkey: int32, 
+  ps_suppkey: int32,
+  ps_availqty: int32,
+  ps_supplycost: double,
+  ps_comment: string 
+}
+
+create dataset LineItem(LineItemType)
+  primary key l_orderkey, l_linenumber;
+create dataset Orders(OrderType)
+  primary key o_orderkey;
+create dataset Supplier(SupplierType)
+  primary key s_suppkey;
+create dataset Region(RegionType) 
+  primary key r_regionkey;
+create dataset Nation(NationType) 
+  primary key n_nationkey;
+create dataset Part(PartType)
+  primary key p_partkey;
+create dataset Partsupp(PartSuppType)
+  primary key ps_partkey, ps_suppkey;  
+create dataset Customer(CustomerType) 
+  primary key c_custkey;
+
+for $p in dataset('Part')
+    for $l2 in (
+      for $ps in dataset('Partsupp')
+      for $l1 in (
+        for $s1 in (
+          for $s in dataset('Supplier')
+          for $n in dataset('Nation')
+          where $n.n_nationkey = $s.s_nationkey
+          return {
+            "s_suppkey": $s.s_suppkey,
+            "n_name": $n.n_name
+          }
+        )
+        for $l in dataset('LineItem')
+        where $s1.s_suppkey = $l.l_suppkey       
+        return  {
+          "l_suppkey": $l.l_suppkey,
+          "l_extendedprice": $l.l_extendedprice,
+          "l_discount": $l.l_discount,
+          "l_quantity": $l.l_quantity,
+          "l_partkey": $l.l_partkey,
+          "l_orderkey": $l.l_orderkey,
+          "n_name": $s1.n_name
+        }
+      )
+      where $ps.ps_suppkey = $l1.l_suppkey and $ps.ps_partkey = $l1.l_partkey       
+      return {
+        "l_extendedprice": $l1.l_extendedprice,
+        "l_discount": $l1.l_discount,
+        "l_quantity": $l1.l_quantity,
+        "l_partkey": $l1.l_partkey,
+        "l_orderkey": $l1.l_orderkey,
+        "n_name": $l1.n_name,
+        "ps_supplycost": $ps.ps_supplycost
+      }
+    )
+    where contains($p.p_name, 'green') and $p.p_partkey = $l2.l_partkey    
+    return {
+      "l_extendedprice": $l2.l_extendedprice,
+      "l_discount": $l2.l_discount,
+      "l_quantity": $l2.l_quantity,
+      "l_orderkey": $l2.l_orderkey,
+      "n_name": $l2.n_name,
+      "ps_supplycost": $l2.ps_supplycost
+    }
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/optimizerts/results/q08_group_by.plan b/asterix-app/src/test/resources/optimizerts/results/q08_group_by.plan
new file mode 100644
index 0000000..fefdfcb
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/q08_group_by.plan
@@ -0,0 +1,78 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- STREAM_PROJECT  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- HYBRID_HASH_JOIN [$$78][$$104]  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- STREAM_PROJECT  |PARTITIONED|
+                  -- ASSIGN  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- DATASOURCE_SCAN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+              -- HASH_PARTITION_EXCHANGE [$$104]  |PARTITIONED|
+                -- STREAM_PROJECT  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- HYBRID_HASH_JOIN [$$101][$$85]  |PARTITIONED|
+                      -- HASH_PARTITION_EXCHANGE [$$101]  |PARTITIONED|
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                            -- HYBRID_HASH_JOIN [$$79][$$81]  |PARTITIONED|
+                              -- HASH_PARTITION_EXCHANGE [$$79]  |PARTITIONED|
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  -- ASSIGN  |PARTITIONED|
+                                    -- STREAM_PROJECT  |PARTITIONED|
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        -- DATASOURCE_SCAN  |PARTITIONED|
+                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                              -- HASH_PARTITION_EXCHANGE [$$81]  |PARTITIONED|
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    -- HYBRID_HASH_JOIN [$$96][$$82]  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$96]  |PARTITIONED|
+                                        -- STREAM_SELECT  |PARTITIONED|
+                                          -- STREAM_PROJECT  |PARTITIONED|
+                                            -- ASSIGN  |PARTITIONED|
+                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                -- DATASOURCE_SCAN  |PARTITIONED|
+                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$82]  |PARTITIONED|
+                                        -- STREAM_PROJECT  |PARTITIONED|
+                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                            -- HYBRID_HASH_JOIN [$$92][$$83]  |PARTITIONED|
+                                              -- HASH_PARTITION_EXCHANGE [$$92]  |PARTITIONED|
+                                                -- STREAM_PROJECT  |PARTITIONED|
+                                                  -- ASSIGN  |PARTITIONED|
+                                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                      -- DATASOURCE_SCAN  |PARTITIONED|
+                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                              -- HASH_PARTITION_EXCHANGE [$$83]  |PARTITIONED|
+                                                -- STREAM_PROJECT  |PARTITIONED|
+                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                    -- HYBRID_HASH_JOIN [$$89][$$84]  |PARTITIONED|
+                                                      -- HASH_PARTITION_EXCHANGE [$$89]  |PARTITIONED|
+                                                        -- STREAM_PROJECT  |PARTITIONED|
+                                                          -- ASSIGN  |PARTITIONED|
+                                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                        -- STREAM_PROJECT  |PARTITIONED|
+                                                          -- STREAM_SELECT  |PARTITIONED|
+                                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          -- STREAM_SELECT  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan b/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan
new file mode 100644
index 0000000..8a08e39
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan
@@ -0,0 +1,55 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- ASSIGN  |PARTITIONED|
+        -- STREAM_PROJECT  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- HYBRID_HASH_JOIN [$$62][$$80]  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- STREAM_PROJECT  |PARTITIONED|
+                  -- STREAM_SELECT  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- DATASOURCE_SCAN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+              -- HASH_PARTITION_EXCHANGE [$$80]  |PARTITIONED|
+                -- STREAM_PROJECT  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- HYBRID_HASH_JOIN [$$64, $$63][$$69, $$80]  |PARTITIONED|
+                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          -- ASSIGN  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                      -- HASH_PARTITION_EXCHANGE [$$80, $$69]  |PARTITIONED|
+                        -- STREAM_PROJECT  |PARTITIONED|
+                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                            -- HYBRID_HASH_JOIN [$$65][$$69]  |PARTITIONED|
+                              -- HASH_PARTITION_EXCHANGE [$$65]  |PARTITIONED|
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    -- HYBRID_HASH_JOIN [$$73][$$66]  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$73]  |PARTITIONED|
+                                        -- STREAM_PROJECT  |PARTITIONED|
+                                          -- ASSIGN  |PARTITIONED|
+                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        -- STREAM_PROJECT  |PARTITIONED|
+                                          -- ASSIGN  |PARTITIONED|
+                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                              -- DATASOURCE_SCAN  |PARTITIONED|
+                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                  -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                              -- HASH_PARTITION_EXCHANGE [$$69]  |PARTITIONED|
+                                -- STREAM_PROJECT  |PARTITIONED|
+                                  -- ASSIGN  |PARTITIONED|
+                                    -- STREAM_PROJECT  |PARTITIONED|
+                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                        -- DATASOURCE_SCAN  |PARTITIONED|
+                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/runtimets/queries/distinct/query-issue443-2/query-issue443-2.3.query.aql b/asterix-app/src/test/resources/runtimets/queries/distinct/query-issue443-2/query-issue443-2.3.query.aql
index eee12d3..38f292b 100644
--- a/asterix-app/src/test/resources/runtimets/queries/distinct/query-issue443-2/query-issue443-2.3.query.aql
+++ b/asterix-app/src/test/resources/runtimets/queries/distinct/query-issue443-2/query-issue443-2.3.query.aql
@@ -5,6 +5,6 @@
  * Date         : 22th May 2013
  */
 
-for $a in [ {"f" : 19, "g": 1} , {"f" : 12, "g": 4} , {"f" : 10, "g": 1} , {"f" : 17, "g": 1}, {"f" : 12, "g": 4} ]
+for $a in [ {"f" : 19, "g": 1} , {"f" : 12, "g": 2} , {"f" : 10, "g": 1} , {"f" : 17, "g": 1}, {"f" : 12, "g": 4} ]
 distinct by $a.f
 return $a
diff --git a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
index 5549c02..b980337 100644
--- a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
+++ b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/MetadataNode.java
@@ -74,7 +74,6 @@
 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.dataflow.common.util.TupleUtils;
-import edu.uci.ics.hyracks.storage.am.btree.exceptions.BTreeDuplicateKeyException;
 import edu.uci.ics.hyracks.storage.am.btree.impls.RangePredicate;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndex;
 import edu.uci.ics.hyracks.storage.am.common.api.IIndexAccessor;
@@ -83,6 +82,7 @@
 import edu.uci.ics.hyracks.storage.am.common.api.IModificationOperationCallback;
 import edu.uci.ics.hyracks.storage.am.common.api.ITreeIndexCursor;
 import edu.uci.ics.hyracks.storage.am.common.api.TreeIndexException;
+import edu.uci.ics.hyracks.storage.am.common.exceptions.TreeIndexDuplicateKeyException;
 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.ophelpers.MultiComparator;
@@ -147,7 +147,7 @@
             DataverseTupleTranslator tupleReaderWriter = new DataverseTupleTranslator(true);
             ITupleReference tuple = tupleReaderWriter.getTupleFromMetadataEntity(dataverse);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.DATAVERSE_DATASET, tuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A dataverse with this name " + dataverse.getDataverseName()
                     + " already exists.", e);
         } catch (Exception e) {
@@ -177,7 +177,7 @@
             ITupleReference dataTypeTuple = createTuple(dataset.getDataverseName(), dataset.getItemTypeName(),
                     dataset.getDatasetName());
             insertTupleIntoIndex(jobId, MetadataSecondaryIndexes.DATATYPENAME_ON_DATASET_INDEX, dataTypeTuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A dataset with this name " + dataset.getDatasetName()
                     + " already exists in dataverse '" + dataset.getDataverseName() + "'.", e);
         } catch (Exception e) {
@@ -191,7 +191,7 @@
             IndexTupleTranslator tupleWriter = new IndexTupleTranslator(true);
             ITupleReference tuple = tupleWriter.getTupleFromMetadataEntity(index);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.INDEX_DATASET, tuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("An index with name '" + index.getIndexName() + "' already exists.", e);
         } catch (Exception e) {
             throw new MetadataException(e);
@@ -204,7 +204,7 @@
             NodeTupleTranslator tupleReaderWriter = new NodeTupleTranslator(true);
             ITupleReference tuple = tupleReaderWriter.getTupleFromMetadataEntity(node);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.NODE_DATASET, tuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A node with name '" + node.getNodeName() + "' already exists.", e);
         } catch (Exception e) {
             throw new MetadataException(e);
@@ -217,7 +217,7 @@
             NodeGroupTupleTranslator tupleReaderWriter = new NodeGroupTupleTranslator(true);
             ITupleReference tuple = tupleReaderWriter.getTupleFromMetadataEntity(nodeGroup);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.NODEGROUP_DATASET, tuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A nodegroup with name '" + nodeGroup.getNodeGroupName() + "' already exists.",
                     e);
         } catch (Exception e) {
@@ -231,7 +231,7 @@
             DatatypeTupleTranslator tupleReaderWriter = new DatatypeTupleTranslator(jobId, this, true);
             ITupleReference tuple = tupleReaderWriter.getTupleFromMetadataEntity(datatype);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.DATATYPE_DATASET, tuple);
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A datatype with name '" + datatype.getDatatypeName() + "' already exists.", e);
         } catch (Exception e) {
             throw new MetadataException(e);
@@ -246,7 +246,7 @@
             ITupleReference functionTuple = tupleReaderWriter.getTupleFromMetadataEntity(function);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.FUNCTION_DATASET, functionTuple);
 
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A function with this name " + function.getName() + " and arity "
                     + function.getArity() + " already exists in dataverse '" + function.getDataverseName() + "'.", e);
         } catch (Exception e) {
@@ -1057,7 +1057,7 @@
             ITupleReference adapterTuple = tupleReaderWriter.getTupleFromMetadataEntity(adapter);
             insertTupleIntoIndex(jobId, MetadataPrimaryIndexes.DATASOURCE_ADAPTER_DATASET, adapterTuple);
 
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             throw new MetadataException("A adapter with this name " + adapter.getAdapterIdentifier().getAdapterName()
                     + " already exists in dataverse '" + adapter.getAdapterIdentifier().getNamespace() + "'.", e);
         } catch (Exception e) {
diff --git a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/entitytupletranslators/DatatypeTupleTranslator.java b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/entitytupletranslators/DatatypeTupleTranslator.java
index 6c55f12..541d703 100644
--- a/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/entitytupletranslators/DatatypeTupleTranslator.java
+++ b/asterix-metadata/src/main/java/edu/uci/ics/asterix/metadata/entitytupletranslators/DatatypeTupleTranslator.java
@@ -55,7 +55,7 @@
 import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
 import edu.uci.ics.hyracks.data.std.util.ArrayBackedValueStorage;
 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.common.exceptions.TreeIndexDuplicateKeyException;
 
 /**
  * Translates a Datatype metadata entity to an ITupleReference and vice versa.
@@ -437,7 +437,7 @@
             mn.insertIntoDatatypeSecondaryIndex(jobId, topLevelType.getDataverseName(), typeName,
                     topLevelType.getDatatypeName());
 
-        } catch (BTreeDuplicateKeyException e) {
+        } catch (TreeIndexDuplicateKeyException e) {
             // The key may have been inserted by a previous DDL statement or by
             // a previous nested type.
         }