diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1047.aql b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1047.aql
new file mode 100644
index 0000000..4210fc3
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1047.aql
@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+/**
+ * This query is to verify the fix of ASTERIXDB-1047.
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+use dataverse test;
+
+create type DBLPType as open {
+  id: int64,
+  dblpid: string,
+  title: string,
+  authors: string,
+  misc: string
+}
+
+create dataset DBLP(DBLPType) primary key id;
+
+
+(for $d in dataset DBLP where $d.id = 1 return $d)
+  union
+(for $d in dataset DBLP where $d.authors = "Alfred V. Aho John E. Hopcroft Jeffrey D. Ullman" return $d);
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-2.aql b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-2.aql
new file mode 100644
index 0000000..82d1430
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-2.aql
@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+/**
+ * This query is to verify the fix of ASTERIXDB-1205.
+ */
+
+let $aa := [{"fa":1, "fb":1}, {"fa":2, "fb":1}]
+let $bb := [{"fa":1, "fb":0}, {"fa":1, "fb":1}, {"fa":3, "fb":1}]
+
+for $tt in ($aa union $bb)
+order by $tt.fa, $tt.fb
+return $tt;
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-3.aql b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-3.aql
new file mode 100644
index 0000000..2ab92dc
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-3.aql
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+/**
+ * This query is to verify the fix of ASTERIXDB-1205.
+ */
+
+let $aa := [{"fa":1, "fb":1}, {"fa":2, "fb":1}]
+let $bb := [{"fa":1, "fb":0}, {"fa":1, "fb":1}, {"fa":3, "fb":1}]
+return $aa union $bb;
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-4.aql b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-4.aql
new file mode 100644
index 0000000..48f7c2a
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205-4.aql
@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+/**
+ * This query is to verify the fix of ASTERIXDB-1205.
+ */
+
+let $aa := [{"fa":1, "fb":1}, {"fa":2, "fb":1}]
+let $bb := [{"fa":1, "fb":0}, {"fa":1, "fb":1}, {"fa":3, "fb":1}]
+let $dd := [{"fa":4, "fb":5}, {"fa":6, "fb":7}]
+let $ccc := $aa union $bb union $dd
+
+for $tt in $ccc
+order by $tt.fa, $tt.fb
+return $tt;
\ No newline at end of file
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205.aql b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205.aql
new file mode 100644
index 0000000..763aba1
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/query-ASTERIXDB-1205.aql
@@ -0,0 +1,29 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+/**
+ * This query is to verify the fix of ASTERIXDB-1205.
+ */
+
+let $aa := [{"fa":1, "fb":1}, {"fa":2, "fb":1}]
+let $bb := [{"fa":1, "fb":0}, {"fa":1, "fb":1}, {"fa":3, "fb":1}]
+let $ccc := $aa union $bb
+
+for $tt in $ccc
+order by $tt.fa, $tt.fb
+return $tt;
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset.aql b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset.aql
new file mode 100644
index 0000000..7a55ee5
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset.aql
@@ -0,0 +1,35 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+drop dataverse TinySocial if exists;
+create dataverse TinySocial;
+use dataverse TinySocial;
+
+create type FacebookUserType as open {
+        id: int
+}
+
+create dataset FacebookUsers(FacebookUserType)
+primary key id;
+
+create dataset FacebookUsers2(FacebookUserType)
+primary key id;
+
+
+let $c := dataset("FacebookUsers") union dataset("FacebookUsers2")
+for $res in $c order by $res.id return $res
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset2.aql b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset2.aql
new file mode 100644
index 0000000..049652f
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset2.aql
@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+drop dataverse TinySocial if exists;
+create dataverse TinySocial;
+use dataverse TinySocial;
+
+create type FacebookUserType as open {
+        id: int
+}
+
+create dataset FacebookUsers(FacebookUserType)
+primary key id;
+
+create dataset FacebookUsers2(FacebookUserType)
+primary key id;
+
+dataset("FacebookUsers") union dataset("FacebookUsers2");
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset3.aql b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset3.aql
new file mode 100644
index 0000000..edb429f
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/union_dataset3.aql
@@ -0,0 +1,35 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+drop dataverse TinySocial if exists;
+create dataverse TinySocial;
+use dataverse TinySocial;
+
+create type FacebookUserType as open {
+        id: int
+}
+
+create dataset FacebookUsers(FacebookUserType)
+primary key id;
+
+create dataset FacebookUsers2(FacebookUserType)
+primary key id;
+
+
+for $res in (dataset("FacebookUsers") union dataset("FacebookUsers2"))
+order by $res.id return $res
diff --git a/asterix-app/src/test/resources/optimizerts/queries/union/union_query.aql b/asterix-app/src/test/resources/optimizerts/queries/union/union_query.aql
new file mode 100644
index 0000000..3e6ebaf
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/queries/union/union_query.aql
@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 at
+ *
+ *   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.
+ */
+
+drop dataverse TinySocial if exists;
+create dataverse TinySocial;
+use dataverse TinySocial;
+
+create type FacebookUserType as open {
+        id: int
+}
+
+create type FacebookMessageType as open {
+        message-id: int
+}
+
+create dataset FacebookUsers(FacebookUserType)
+primary key id;
+
+create dataset FacebookMessages(FacebookMessageType)
+primary key message-id;
+
+let $t1 := for $t in dataset FacebookUsers return $t.id
+let $t2 := for $s in dataset FacebookMessages return $s.message-id
+let $c := $t1 union $t2
+for $res in $c distinct by $res order by $res return $res
diff --git a/asterix-app/src/test/resources/optimizerts/results/q05_local_supplier_volume.plan b/asterix-app/src/test/resources/optimizerts/results/q05_local_supplier_volume.plan
index 1f99eee..9d17ca8 100644
--- a/asterix-app/src/test/resources/optimizerts/results/q05_local_supplier_volume.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/q05_local_supplier_volume.plan
@@ -2,8 +2,8 @@
   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
     -- STREAM_PROJECT  |PARTITIONED|
       -- ASSIGN  |PARTITIONED|
-        -- SORT_MERGE_EXCHANGE [$$100(DESC) ]  |PARTITIONED|
-          -- STABLE_SORT [$$100(DESC)]  |PARTITIONED|
+        -- SORT_MERGE_EXCHANGE [$$89(DESC) ]  |PARTITIONED|
+          -- STABLE_SORT [$$89(DESC)]  |PARTITIONED|
             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
               -- EXTERNAL_GROUP_BY[$$119]  |PARTITIONED|
                       {
@@ -19,7 +19,7 @@
                     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                       -- STREAM_PROJECT  |PARTITIONED|
                         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                          -- HYBRID_HASH_JOIN [$$81, $$98][$$115, $$88]  |PARTITIONED|
+                          -- HYBRID_HASH_JOIN [$$94, $$81][$$88, $$115]  |PARTITIONED|
                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                               -- STREAM_PROJECT  |PARTITIONED|
                                 -- ASSIGN  |PARTITIONED|
@@ -66,8 +66,8 @@
                                                     -- HASH_PARTITION_EXCHANGE [$$86]  |PARTITIONED|
                                                       -- STREAM_PROJECT  |PARTITIONED|
                                                         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                          -- HYBRID_HASH_JOIN [$$89][$$87]  |PARTITIONED|
-                                                            -- HASH_PARTITION_EXCHANGE [$$89]  |PARTITIONED|
+                                                          -- HYBRID_HASH_JOIN [$$90][$$87]  |PARTITIONED|
+                                                            -- HASH_PARTITION_EXCHANGE [$$90]  |PARTITIONED|
                                                               -- STREAM_PROJECT  |PARTITIONED|
                                                                 -- ASSIGN  |PARTITIONED|
                                                                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
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
index 601091e..1aca471 100644
--- a/asterix-app/src/test/resources/optimizerts/results/q08_group_by.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/q08_group_by.plan
@@ -31,8 +31,8 @@
                               -- HASH_PARTITION_EXCHANGE [$$81]  |PARTITIONED|
                                 -- STREAM_PROJECT  |PARTITIONED|
                                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                    -- HYBRID_HASH_JOIN [$$92][$$82]  |PARTITIONED|
-                                      -- HASH_PARTITION_EXCHANGE [$$92]  |PARTITIONED|
+                                    -- HYBRID_HASH_JOIN [$$94][$$82]  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$94]  |PARTITIONED|
                                         -- STREAM_SELECT  |PARTITIONED|
                                           -- STREAM_PROJECT  |PARTITIONED|
                                             -- ASSIGN  |PARTITIONED|
@@ -43,8 +43,8 @@
                                       -- HASH_PARTITION_EXCHANGE [$$82]  |PARTITIONED|
                                         -- STREAM_PROJECT  |PARTITIONED|
                                           -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                            -- HYBRID_HASH_JOIN [$$89][$$83]  |PARTITIONED|
-                                              -- HASH_PARTITION_EXCHANGE [$$89]  |PARTITIONED|
+                                            -- HYBRID_HASH_JOIN [$$91][$$83]  |PARTITIONED|
+                                              -- HASH_PARTITION_EXCHANGE [$$91]  |PARTITIONED|
                                                 -- STREAM_PROJECT  |PARTITIONED|
                                                   -- ASSIGN  |PARTITIONED|
                                                     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
@@ -54,8 +54,8 @@
                                               -- HASH_PARTITION_EXCHANGE [$$83]  |PARTITIONED|
                                                 -- STREAM_PROJECT  |PARTITIONED|
                                                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                    -- HYBRID_HASH_JOIN [$$87][$$84]  |PARTITIONED|
-                                                      -- HASH_PARTITION_EXCHANGE [$$87]  |PARTITIONED|
+                                                    -- HYBRID_HASH_JOIN [$$89][$$84]  |PARTITIONED|
+                                                      -- HASH_PARTITION_EXCHANGE [$$89]  |PARTITIONED|
                                                         -- STREAM_PROJECT  |PARTITIONED|
                                                           -- ASSIGN  |PARTITIONED|
                                                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan b/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan
index fc2abd2..9f48723 100644
--- a/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/q09_group_by.plan
@@ -15,7 +15,7 @@
               -- HASH_PARTITION_EXCHANGE [$$84]  |PARTITIONED|
                 -- STREAM_PROJECT  |PARTITIONED|
                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                    -- HYBRID_HASH_JOIN [$$64, $$63][$$69, $$84]  |PARTITIONED|
+                    -- HYBRID_HASH_JOIN [$$63, $$64][$$84, $$69]  |PARTITIONED|
                       -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                         -- STREAM_PROJECT  |PARTITIONED|
                           -- ASSIGN  |PARTITIONED|
@@ -30,8 +30,8 @@
                               -- HASH_PARTITION_EXCHANGE [$$65]  |PARTITIONED|
                                 -- STREAM_PROJECT  |PARTITIONED|
                                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                    -- HYBRID_HASH_JOIN [$$77][$$66]  |PARTITIONED|
-                                      -- HASH_PARTITION_EXCHANGE [$$77]  |PARTITIONED|
+                                    -- HYBRID_HASH_JOIN [$$72][$$66]  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$72]  |PARTITIONED|
                                         -- STREAM_PROJECT  |PARTITIONED|
                                           -- ASSIGN  |PARTITIONED|
                                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/query-issue562.plan b/asterix-app/src/test/resources/optimizerts/results/query-issue562.plan
index 5062719..28625aa 100644
--- a/asterix-app/src/test/resources/optimizerts/results/query-issue562.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/query-issue562.plan
@@ -3,12 +3,12 @@
     -- STREAM_PROJECT  |PARTITIONED|
       -- ASSIGN  |PARTITIONED|
         -- SORT_MERGE_EXCHANGE [$$7(ASC) ]  |PARTITIONED|
-          -- PRE_CLUSTERED_GROUP_BY[$$89]  |PARTITIONED|
+          -- PRE_CLUSTERED_GROUP_BY[$$86]  |PARTITIONED|
                   {
                     -- AGGREGATE  |LOCAL|
                       -- NESTED_TUPLE_SOURCE  |LOCAL|
                   }
-            -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$89(ASC)] HASH:[$$89]  |PARTITIONED|
+            -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$86(ASC)] HASH:[$$86]  |PARTITIONED|
               -- SORT_GROUP_BY[$$59]  |PARTITIONED|
                       {
                         -- AGGREGATE  |LOCAL|
@@ -21,46 +21,48 @@
                         -- STREAM_SELECT  |PARTITIONED|
                           -- STREAM_PROJECT  |PARTITIONED|
                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                              -- PRE_CLUSTERED_GROUP_BY[$$86]  |PARTITIONED|
+                              -- SORT_GROUP_BY[$$83]  |PARTITIONED|
                                       {
                                         -- AGGREGATE  |LOCAL|
                                           -- NESTED_TUPLE_SOURCE  |LOCAL|
                                       }
-                                -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$86(ASC)] HASH:[$$86]  |PARTITIONED|
-                                  -- PRE_CLUSTERED_GROUP_BY[$$62]  |PARTITIONED|
-                                          {
-                                            -- AGGREGATE  |LOCAL|
-                                              -- STREAM_SELECT  |LOCAL|
-                                                -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                          }
+                                -- HASH_PARTITION_EXCHANGE [$$83]  |PARTITIONED|
+                                  -- STREAM_PROJECT  |PARTITIONED|
                                     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                      -- STABLE_SORT [$$62(ASC)]  |PARTITIONED|
+                                      -- PRE_CLUSTERED_GROUP_BY[$$65, $$11, $$62]  |PARTITIONED|
+                                              {
+                                                -- AGGREGATE  |LOCAL|
+                                                  -- STREAM_SELECT  |LOCAL|
+                                                    -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                              }
                                         -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                          -- STREAM_PROJECT  |PARTITIONED|
+                                          -- STABLE_SORT [$$65(ASC), $$65(ASC), $$62(ASC)]  |PARTITIONED|
                                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                              -- HYBRID_HASH_JOIN [$$67][$$68]  |PARTITIONED|
-                                                -- HASH_PARTITION_EXCHANGE [$$67]  |PARTITIONED|
-                                                  -- ASSIGN  |PARTITIONED|
-                                                    -- STREAM_PROJECT  |PARTITIONED|
-                                                      -- ASSIGN  |PARTITIONED|
-                                                        -- STREAM_PROJECT  |PARTITIONED|
-                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                            -- HYBRID_HASH_JOIN [$$83][$$82]  |PARTITIONED|
-                                                              -- HASH_PARTITION_EXCHANGE [$$83]  |PARTITIONED|
-                                                                -- UNNEST  |UNPARTITIONED|
-                                                                  -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
-                                                              -- HASH_PARTITION_EXCHANGE [$$82]  |PARTITIONED|
-                                                                -- ASSIGN  |PARTITIONED|
-                                                                  -- STREAM_PROJECT  |PARTITIONED|
+                                              -- STABLE_SORT [$$65(ASC), $$65(ASC), $$62(ASC)]  |PARTITIONED|
+                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                  -- STREAM_PROJECT  |PARTITIONED|
+                                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                      -- HYBRID_HASH_JOIN [$$68][$$69]  |PARTITIONED|
+                                                        -- HASH_PARTITION_EXCHANGE [$$68]  |PARTITIONED|
+                                                          -- ASSIGN  |PARTITIONED|
+                                                            -- ASSIGN  |PARTITIONED|
+                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                -- HYBRID_HASH_JOIN [$$65][$$11]  |PARTITIONED|
+                                                                  -- HASH_PARTITION_EXCHANGE [$$65]  |PARTITIONED|
+                                                                    -- UNNEST  |UNPARTITIONED|
+                                                                      -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+                                                                  -- HASH_PARTITION_EXCHANGE [$$11]  |PARTITIONED|
                                                                     -- ASSIGN  |PARTITIONED|
-                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                        -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                      -- STREAM_PROJECT  |PARTITIONED|
+                                                                        -- ASSIGN  |PARTITIONED|
                                                                           -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
-                                                -- HASH_PARTITION_EXCHANGE [$$68]  |PARTITIONED|
-                                                  -- ASSIGN  |PARTITIONED|
-                                                    -- STREAM_PROJECT  |PARTITIONED|
-                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                        -- DATASOURCE_SCAN  |PARTITIONED|
-                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                                            -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                        -- HASH_PARTITION_EXCHANGE [$$69]  |PARTITIONED|
+                                                          -- ASSIGN  |PARTITIONED|
+                                                            -- STREAM_PROJECT  |PARTITIONED|
+                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/split-materialization-above-join.plan b/asterix-app/src/test/resources/optimizerts/results/split-materialization-above-join.plan
index 19eaf25..f22f71a 100644
--- a/asterix-app/src/test/resources/optimizerts/results/split-materialization-above-join.plan
+++ b/asterix-app/src/test/resources/optimizerts/results/split-materialization-above-join.plan
@@ -8,151 +8,153 @@
               -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                 -- STREAM_PROJECT  |PARTITIONED|
                   -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                    -- HYBRID_HASH_JOIN [$$94, $$93][$$26, $$25]  |PARTITIONED|
-                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                        -- NESTED_LOOP  |PARTITIONED|
-                          -- BROADCAST_EXCHANGE  |PARTITIONED|
-                            -- DATASOURCE_SCAN  |PARTITIONED|
-                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
-                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                            -- STREAM_PROJECT  |PARTITIONED|
-                              -- ASSIGN  |PARTITIONED|
-                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                  -- SPLIT  |PARTITIONED|
-                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                      -- DATASOURCE_SCAN  |PARTITIONED|
-                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                    -- HYBRID_HASH_JOIN [$$26][$$94]  |PARTITIONED|
                       -- HASH_PARTITION_EXCHANGE [$$26]  |PARTITIONED|
-                        -- PRE_CLUSTERED_GROUP_BY[$$122, $$124]  |PARTITIONED|
-                                {
-                                  -- AGGREGATE  |LOCAL|
-                                    -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                }
+                        -- STREAM_PROJECT  |PARTITIONED|
                           -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                            -- STABLE_SORT [$$122(ASC), $$124(ASC)]  |PARTITIONED|
-                              -- HASH_PARTITION_EXCHANGE [$$122, $$124]  |PARTITIONED|
-                                -- STREAM_PROJECT  |PARTITIONED|
-                                  -- ASSIGN  |PARTITIONED|
-                                    -- STREAM_SELECT  |PARTITIONED|
-                                      -- STREAM_PROJECT  |PARTITIONED|
-                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                          -- HYBRID_HASH_JOIN [$$12][$$23]  |PARTITIONED|
-                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                            -- HYBRID_HASH_JOIN [$$93][$$25]  |PARTITIONED|
+                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                -- DATASOURCE_SCAN  |PARTITIONED|
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                              -- HASH_PARTITION_EXCHANGE [$$25]  |PARTITIONED|
+                                -- PRE_CLUSTERED_GROUP_BY[$$122, $$124]  |PARTITIONED|
+                                        {
+                                          -- AGGREGATE  |LOCAL|
+                                            -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                        }
+                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                    -- STABLE_SORT [$$122(ASC), $$124(ASC)]  |PARTITIONED|
+                                      -- HASH_PARTITION_EXCHANGE [$$122, $$124]  |PARTITIONED|
+                                        -- STREAM_PROJECT  |PARTITIONED|
+                                          -- ASSIGN  |PARTITIONED|
+                                            -- STREAM_SELECT  |PARTITIONED|
                                               -- STREAM_PROJECT  |PARTITIONED|
-                                                -- ASSIGN  |PARTITIONED|
-                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                    -- SPLIT  |PARTITIONED|
-                                                      -- HASH_PARTITION_EXCHANGE [$$23]  |PARTITIONED|
-                                                        -- UNNEST  |PARTITIONED|
-                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                            -- PRE_CLUSTERED_GROUP_BY[$$97]  |PARTITIONED|
-                                                                    {
-                                                                      -- AGGREGATE  |LOCAL|
-                                                                        -- STREAM_SELECT  |LOCAL|
-                                                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                                    }
-                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                -- STABLE_SORT [$$97(ASC), $$21(ASC)]  |PARTITIONED|
-                                                                  -- HASH_PARTITION_EXCHANGE [$$97]  |PARTITIONED|
-                                                                    -- STREAM_PROJECT  |PARTITIONED|
-                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                        -- HYBRID_HASH_JOIN [$$15][$$18]  |PARTITIONED|
-                                                                          -- HASH_PARTITION_EXCHANGE [$$15]  |PARTITIONED|
-                                                                            -- STREAM_PROJECT  |PARTITIONED|
-                                                                              -- UNNEST  |PARTITIONED|
-                                                                                -- ASSIGN  |PARTITIONED|
-                                                                                  -- STREAM_PROJECT  |PARTITIONED|
-                                                                                    -- ASSIGN  |PARTITIONED|
-                                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                        -- DATASOURCE_SCAN  |PARTITIONED|
-                                                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
-                                                                          -- HASH_PARTITION_EXCHANGE [$$18]  |PARTITIONED|
-                                                                            -- ASSIGN  |PARTITIONED|
-                                                                              -- RUNNING_AGGREGATE  |PARTITIONED|
-                                                                                -- STREAM_PROJECT  |PARTITIONED|
-                                                                                  -- SORT_MERGE_EXCHANGE [$$105(ASC), $$18(ASC) ]  |PARTITIONED|
-                                                                                    -- STABLE_SORT [$$105(ASC), $$18(ASC)]  |PARTITIONED|
-                                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                        -- PRE_CLUSTERED_GROUP_BY[$$130]  |PARTITIONED|
-                                                                                                {
-                                                                                                  -- AGGREGATE  |LOCAL|
-                                                                                                    -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                                                                }
-                                                                                          -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$130(ASC)] HASH:[$$130]  |PARTITIONED|
-                                                                                            -- SORT_GROUP_BY[$$17]  |PARTITIONED|
-                                                                                                    {
-                                                                                                      -- AGGREGATE  |LOCAL|
-                                                                                                        -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                                                                    }
-                                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                -- STREAM_PROJECT  |PARTITIONED|
-                                                                                                  -- UNNEST  |PARTITIONED|
-                                                                                                    -- STREAM_PROJECT  |PARTITIONED|
-                                                                                                      -- ASSIGN  |PARTITIONED|
-                                                                                                        -- STREAM_PROJECT  |PARTITIONED|
-                                                                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                            -- SPLIT  |PARTITIONED|
-                                                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                                -- DATASOURCE_SCAN  |PARTITIONED|
-                                                                                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
-                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                              -- SPLIT  |PARTITIONED|
-                                                -- HASH_PARTITION_EXCHANGE [$$23]  |PARTITIONED|
-                                                  -- UNNEST  |PARTITIONED|
+                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                  -- HYBRID_HASH_JOIN [$$12][$$23]  |PARTITIONED|
                                                     -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                      -- PRE_CLUSTERED_GROUP_BY[$$97]  |PARTITIONED|
-                                                              {
-                                                                -- AGGREGATE  |LOCAL|
-                                                                  -- STREAM_SELECT  |LOCAL|
-                                                                    -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                              }
-                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                          -- STABLE_SORT [$$97(ASC), $$21(ASC)]  |PARTITIONED|
-                                                            -- HASH_PARTITION_EXCHANGE [$$97]  |PARTITIONED|
-                                                              -- STREAM_PROJECT  |PARTITIONED|
-                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                  -- HYBRID_HASH_JOIN [$$15][$$18]  |PARTITIONED|
-                                                                    -- HASH_PARTITION_EXCHANGE [$$15]  |PARTITIONED|
-                                                                      -- STREAM_PROJECT  |PARTITIONED|
-                                                                        -- UNNEST  |PARTITIONED|
-                                                                          -- ASSIGN  |PARTITIONED|
+                                                      -- STREAM_PROJECT  |PARTITIONED|
+                                                        -- ASSIGN  |PARTITIONED|
+                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                            -- SPLIT  |PARTITIONED|
+                                                              -- HASH_PARTITION_EXCHANGE [$$23]  |PARTITIONED|
+                                                                -- UNNEST  |PARTITIONED|
+                                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                    -- PRE_CLUSTERED_GROUP_BY[$$97]  |PARTITIONED|
+                                                                            {
+                                                                              -- AGGREGATE  |LOCAL|
+                                                                                -- STREAM_SELECT  |LOCAL|
+                                                                                  -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                            }
+                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                        -- STABLE_SORT [$$97(ASC), $$21(ASC)]  |PARTITIONED|
+                                                                          -- HASH_PARTITION_EXCHANGE [$$97]  |PARTITIONED|
                                                                             -- STREAM_PROJECT  |PARTITIONED|
-                                                                              -- ASSIGN  |PARTITIONED|
-                                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                  -- DATASOURCE_SCAN  |PARTITIONED|
-                                                                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                      -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
-                                                                    -- HASH_PARTITION_EXCHANGE [$$18]  |PARTITIONED|
-                                                                      -- ASSIGN  |PARTITIONED|
-                                                                        -- RUNNING_AGGREGATE  |PARTITIONED|
-                                                                          -- STREAM_PROJECT  |PARTITIONED|
-                                                                            -- SORT_MERGE_EXCHANGE [$$105(ASC), $$18(ASC) ]  |PARTITIONED|
-                                                                              -- STABLE_SORT [$$105(ASC), $$18(ASC)]  |PARTITIONED|
-                                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                  -- PRE_CLUSTERED_GROUP_BY[$$130]  |PARTITIONED|
-                                                                                          {
-                                                                                            -- AGGREGATE  |LOCAL|
-                                                                                              -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                                                          }
-                                                                                    -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$130(ASC)] HASH:[$$130]  |PARTITIONED|
-                                                                                      -- SORT_GROUP_BY[$$17]  |PARTITIONED|
-                                                                                              {
-                                                                                                -- AGGREGATE  |LOCAL|
-                                                                                                  -- NESTED_TUPLE_SOURCE  |LOCAL|
-                                                                                              }
-                                                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                -- HYBRID_HASH_JOIN [$$15][$$18]  |PARTITIONED|
+                                                                                  -- HASH_PARTITION_EXCHANGE [$$15]  |PARTITIONED|
+                                                                                    -- STREAM_PROJECT  |PARTITIONED|
+                                                                                      -- UNNEST  |PARTITIONED|
+                                                                                        -- ASSIGN  |PARTITIONED|
                                                                                           -- STREAM_PROJECT  |PARTITIONED|
-                                                                                            -- UNNEST  |PARTITIONED|
-                                                                                              -- STREAM_PROJECT  |PARTITIONED|
-                                                                                                -- ASSIGN  |PARTITIONED|
+                                                                                            -- ASSIGN  |PARTITIONED|
+                                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                                                  -- HASH_PARTITION_EXCHANGE [$$18]  |PARTITIONED|
+                                                                                    -- ASSIGN  |PARTITIONED|
+                                                                                      -- RUNNING_AGGREGATE  |PARTITIONED|
+                                                                                        -- STREAM_PROJECT  |PARTITIONED|
+                                                                                          -- SORT_MERGE_EXCHANGE [$$102(ASC), $$18(ASC) ]  |PARTITIONED|
+                                                                                            -- STABLE_SORT [$$102(ASC), $$18(ASC)]  |PARTITIONED|
+                                                                                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                -- PRE_CLUSTERED_GROUP_BY[$$130]  |PARTITIONED|
+                                                                                                        {
+                                                                                                          -- AGGREGATE  |LOCAL|
+                                                                                                            -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                                                        }
+                                                                                                  -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$130(ASC)] HASH:[$$130]  |PARTITIONED|
+                                                                                                    -- SORT_GROUP_BY[$$17]  |PARTITIONED|
+                                                                                                            {
+                                                                                                              -- AGGREGATE  |LOCAL|
+                                                                                                                -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                                                            }
+                                                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                        -- STREAM_PROJECT  |PARTITIONED|
+                                                                                                          -- UNNEST  |PARTITIONED|
+                                                                                                            -- STREAM_PROJECT  |PARTITIONED|
+                                                                                                              -- ASSIGN  |PARTITIONED|
+                                                                                                                -- STREAM_PROJECT  |PARTITIONED|
+                                                                                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                                    -- SPLIT  |PARTITIONED|
+                                                                                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                                        -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                                                                          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                                                            -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                      -- SPLIT  |PARTITIONED|
+                                                        -- HASH_PARTITION_EXCHANGE [$$23]  |PARTITIONED|
+                                                          -- UNNEST  |PARTITIONED|
+                                                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                              -- PRE_CLUSTERED_GROUP_BY[$$97]  |PARTITIONED|
+                                                                      {
+                                                                        -- AGGREGATE  |LOCAL|
+                                                                          -- STREAM_SELECT  |LOCAL|
+                                                                            -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                      }
+                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                  -- STABLE_SORT [$$97(ASC), $$21(ASC)]  |PARTITIONED|
+                                                                    -- HASH_PARTITION_EXCHANGE [$$97]  |PARTITIONED|
+                                                                      -- STREAM_PROJECT  |PARTITIONED|
+                                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                          -- HYBRID_HASH_JOIN [$$15][$$18]  |PARTITIONED|
+                                                                            -- HASH_PARTITION_EXCHANGE [$$15]  |PARTITIONED|
+                                                                              -- STREAM_PROJECT  |PARTITIONED|
+                                                                                -- UNNEST  |PARTITIONED|
+                                                                                  -- ASSIGN  |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 [$$18]  |PARTITIONED|
+                                                                              -- ASSIGN  |PARTITIONED|
+                                                                                -- RUNNING_AGGREGATE  |PARTITIONED|
+                                                                                  -- STREAM_PROJECT  |PARTITIONED|
+                                                                                    -- SORT_MERGE_EXCHANGE [$$102(ASC), $$18(ASC) ]  |PARTITIONED|
+                                                                                      -- STABLE_SORT [$$102(ASC), $$18(ASC)]  |PARTITIONED|
+                                                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                                                          -- PRE_CLUSTERED_GROUP_BY[$$130]  |PARTITIONED|
+                                                                                                  {
+                                                                                                    -- AGGREGATE  |LOCAL|
+                                                                                                      -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                                                  }
+                                                                                            -- HASH_PARTITION_MERGE_EXCHANGE MERGE:[$$130(ASC)] HASH:[$$130]  |PARTITIONED|
+                                                                                              -- SORT_GROUP_BY[$$17]  |PARTITIONED|
+                                                                                                      {
+                                                                                                        -- AGGREGATE  |LOCAL|
+                                                                                                          -- NESTED_TUPLE_SOURCE  |LOCAL|
+                                                                                                      }
+                                                                                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
                                                                                                   -- STREAM_PROJECT  |PARTITIONED|
-                                                                                                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                      -- SPLIT  |PARTITIONED|
-                                                                                                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                          -- DATASOURCE_SCAN  |PARTITIONED|
+                                                                                                    -- UNNEST  |PARTITIONED|
+                                                                                                      -- STREAM_PROJECT  |PARTITIONED|
+                                                                                                        -- ASSIGN  |PARTITIONED|
+                                                                                                          -- STREAM_PROJECT  |PARTITIONED|
                                                                                                             -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                                                                                              -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+                                                                                                              -- SPLIT  |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|
+                              -- SPLIT  |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/union/query-ASTERIXDB-1047.plan b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1047.plan
new file mode 100644
index 0000000..59a50fb
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1047.plan
@@ -0,0 +1,19 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- AGGREGATE  |UNPARTITIONED|
+      -- RANDOM_MERGE_EXCHANGE  |PARTITIONED|
+        -- UNION_ALL  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- STREAM_PROJECT  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- BTREE_SEARCH  |PARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- ASSIGN  |PARTITIONED|
+                      -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- STREAM_SELECT  |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/optimizerts/results/union/query-ASTERIXDB-1205-2.plan b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-2.plan
new file mode 100644
index 0000000..1d21071
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-2.plan
@@ -0,0 +1,19 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+        -- STABLE_SORT [$$19(ASC), $$20(ASC)]  |UNPARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+            -- UNION_ALL  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- STREAM_PROJECT  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- ASSIGN  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- STREAM_PROJECT  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- ASSIGN  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-3.plan b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-3.plan
new file mode 100644
index 0000000..a1f37e8
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-3.plan
@@ -0,0 +1,15 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- AGGREGATE  |UNPARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+        -- UNION_ALL  |UNPARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+            -- STREAM_PROJECT  |UNPARTITIONED|
+              -- UNNEST  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+            -- STREAM_PROJECT  |UNPARTITIONED|
+              -- UNNEST  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-4.plan b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-4.plan
new file mode 100644
index 0000000..48950e8
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205-4.plan
@@ -0,0 +1,27 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+        -- STABLE_SORT [$$28(ASC), $$29(ASC)]  |UNPARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+            -- UNION_ALL  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- UNION_ALL  |UNPARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                    -- ASSIGN  |UNPARTITIONED|
+                      -- STREAM_PROJECT  |UNPARTITIONED|
+                        -- UNNEST  |UNPARTITIONED|
+                          -- ASSIGN  |UNPARTITIONED|
+                            -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+                  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                    -- ASSIGN  |UNPARTITIONED|
+                      -- STREAM_PROJECT  |UNPARTITIONED|
+                        -- UNNEST  |UNPARTITIONED|
+                          -- ASSIGN  |UNPARTITIONED|
+                            -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- STREAM_PROJECT  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- ASSIGN  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205.plan b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205.plan
new file mode 100644
index 0000000..115b5b6
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/query-ASTERIXDB-1205.plan
@@ -0,0 +1,19 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+        -- STABLE_SORT [$$20(ASC), $$21(ASC)]  |UNPARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+            -- UNION_ALL  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- STREAM_PROJECT  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- ASSIGN  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- STREAM_PROJECT  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- ASSIGN  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/union/union_dataset.plan b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset.plan
new file mode 100644
index 0000000..fdc7d4c
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset.plan
@@ -0,0 +1,21 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- SORT_MERGE_EXCHANGE [$$11(ASC) ]  |PARTITIONED|
+        -- STABLE_SORT [$$11(ASC)]  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- UNION_ALL  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_PROJECT  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- DATASOURCE_SCAN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |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/optimizerts/results/union/union_dataset2.plan b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset2.plan
new file mode 100644
index 0000000..c1b97aa
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset2.plan
@@ -0,0 +1,17 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- AGGREGATE  |UNPARTITIONED|
+      -- RANDOM_MERGE_EXCHANGE  |PARTITIONED|
+        -- UNION_ALL  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- STREAM_PROJECT  |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|
+              -- 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/union/union_dataset3.plan b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset3.plan
new file mode 100644
index 0000000..9d51d1c
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/union_dataset3.plan
@@ -0,0 +1,21 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- STREAM_PROJECT  |PARTITIONED|
+      -- SORT_MERGE_EXCHANGE [$$10(ASC) ]  |PARTITIONED|
+        -- STABLE_SORT [$$10(ASC)]  |PARTITIONED|
+          -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+            -- UNION_ALL  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_PROJECT  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- DATASOURCE_SCAN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_PROJECT  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- DATASOURCE_SCAN  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterix-app/src/test/resources/optimizerts/results/union/union_query.plan b/asterix-app/src/test/resources/optimizerts/results/union/union_query.plan
new file mode 100644
index 0000000..67de4c9
--- /dev/null
+++ b/asterix-app/src/test/resources/optimizerts/results/union/union_query.plan
@@ -0,0 +1,19 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- SORT_MERGE_EXCHANGE [$$16(ASC) ]  |PARTITIONED|
+    -- PRE_SORTED_DISTINCT_BY  |PARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+        -- STABLE_SORT [$$16(ASC)]  |PARTITIONED|
+          -- HASH_PARTITION_EXCHANGE [$$16]  |PARTITIONED|
+            -- UNION_ALL  |PARTITIONED|
+              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                -- STREAM_PROJECT  |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|
+                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                    -- DATASOURCE_SCAN  |PARTITIONED|
+                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|