diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/base/RuleCollections.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/base/RuleCollections.java
index ece78f8..80469a7 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/base/RuleCollections.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/base/RuleCollections.java
@@ -94,6 +94,8 @@
 import org.apache.hyracks.algebricks.rewriter.rules.ComplexUnnestToProductRule;
 import org.apache.hyracks.algebricks.rewriter.rules.ConsolidateAssignsRule;
 import org.apache.hyracks.algebricks.rewriter.rules.ConsolidateSelectsRule;
+import org.apache.hyracks.algebricks.rewriter.rules.ReuseWindowAggregateRule;
+import org.apache.hyracks.algebricks.rewriter.rules.ConsolidateWindowOperatorsRule;
 import org.apache.hyracks.algebricks.rewriter.rules.CopyLimitDownRule;
 import org.apache.hyracks.algebricks.rewriter.rules.EliminateGroupByEmptyKeyRule;
 import org.apache.hyracks.algebricks.rewriter.rules.EnforceOrderByAfterSubplan;
@@ -291,6 +293,10 @@
         //PushUnnestDownUnion => RemoveRedundantListifyRule cause these rules are correlated
         consolidation.add(new PushUnnestDownThroughUnionRule());
         consolidation.add(new RemoveRedundantListifyRule());
+        // Window operator consolidation rules
+        consolidation.add(new ConsolidateWindowOperatorsRule());
+        consolidation.add(new ReuseWindowAggregateRule());
+        consolidation.add(new RemoveRedundantVariablesRule());
         return consolidation;
     }
 
diff --git a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/LoadRecordFieldsRule.java b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/LoadRecordFieldsRule.java
index 32fa744..4d61307 100644
--- a/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/LoadRecordFieldsRule.java
+++ b/asterixdb/asterix-algebra/src/main/java/org/apache/asterix/optimizer/rules/LoadRecordFieldsRule.java
@@ -321,10 +321,10 @@
                 }
             } else if (opChild.getOperatorTag() == LogicalOperatorTag.NESTEDTUPLESOURCE) {
                 NestedTupleSourceOperator nts = (NestedTupleSourceOperator) opChild;
-                AbstractLogicalOperator opBelowNestedPlan =
-                        (AbstractLogicalOperator) nts.getDataSourceReference().getValue().getInputs().get(0).getValue();
+                AbstractLogicalOperator opWithNestedPlan =
+                        (AbstractLogicalOperator) nts.getDataSourceReference().getValue();
                 ILogicalExpression expr1 =
-                        findFieldExpression(opBelowNestedPlan, recordVar, accessKey, typeEnvironment, resolver);
+                        findFieldExpression(opWithNestedPlan, recordVar, accessKey, typeEnvironment, resolver);
                 if (expr1 != null) {
                     return expr1;
                 }
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/window_01.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_misc/win_misc_01.sqlpp
similarity index 100%
rename from asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/window_01.sqlpp
rename to asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_misc/win_misc_01.sqlpp
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/window_02.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_misc/win_misc_02.sqlpp
similarity index 100%
rename from asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/window_02.sqlpp
rename to asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_misc/win_misc_02.sqlpp
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_1.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_1.sqlpp
new file mode 100644
index 0000000..d53d092
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_1.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of two running aggregates
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  round_half_to_even(percent_rank() over (partition by m order by t), 2)  as `percent_rank`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_2.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_2.sqlpp
new file mode 100644
index 0000000..c403726
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_2.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate and one regular aggregate
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t) over (partition by m order by t) as `sum`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_3.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_3.sqlpp
new file mode 100644
index 0000000..25d559d
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_3.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate
+ *                and one regular aggregate with complex argument
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t + m) over (partition by m order by t) as `sum`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_4.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_4.sqlpp
new file mode 100644
index 0000000..06f5ac3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_4.sqlpp
@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate and
+ *                two regular aggregates with complex arguments
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t + m) over (partition by m order by t) as `sum`,
+  round_half_to_even(avg(t - m) over (partition by m order by t), 2) as `avg`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_5.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_5.sqlpp
new file mode 100644
index 0000000..b6bfd66
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_5.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of two window functions in LET clauses
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t, row_number, ntile
+FROM range(1, 16) t
+LET m = t % 4,
+    row_number = row_number() over (partition by m order by t),
+    ntile = ntile(2) over (partition by m order by t)
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_6.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_6.sqlpp
new file mode 100644
index 0000000..0019ba8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_6.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of data dependency between two window functions.
+ *                No operator consolidation in this case.
+ * Expected Res : SUCCESS (two window operators in the optimized plan)
+ */
+
+SELECT m, t, row_number, ntile
+FROM range(1, 16) t
+LET m = t % 4,
+    row_number = row_number() over (partition by m order by t),
+    ntile = ntile(row_number + 1) over (partition by m order by t)
+ORDER BY m, t;
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_7.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_7.sqlpp
new file mode 100644
index 0000000..f139ab8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/window/win_opt_01/win_opt_01_7.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of ROW frame mode
+ * Expected Res : SUCCESS (two window operators in the optimized plan)
+ */
+
+SELECT m, t,
+  sum(t) over (partition by m order by t rows between unbounded preceding and current row) as `sum`,
+  round_half_to_even(avg(t) over (partition by m order by t rows between unbounded preceding and current row), 2) as `avg`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_misc/win_misc_01.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_misc/win_misc_01.plan
new file mode 100644
index 0000000..8191e74
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_misc/win_misc_01.plan
@@ -0,0 +1,29 @@
+-- DISTRIBUTE_RESULT  |UNPARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+    -- STREAM_PROJECT  |UNPARTITIONED|
+      -- ASSIGN  |UNPARTITIONED|
+        -- AGGREGATE  |UNPARTITIONED|
+          -- RANDOM_MERGE_EXCHANGE  |PARTITIONED|
+            -- AGGREGATE  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ASSIGN  |PARTITIONED|
+                  -- STREAM_PROJECT  |PARTITIONED|
+                    -- ASSIGN  |PARTITIONED|
+                      -- STREAM_PROJECT  |PARTITIONED|
+                        -- ASSIGN  |PARTITIONED|
+                          -- STREAM_PROJECT  |PARTITIONED|
+                            -- WINDOW  |PARTITIONED|
+                              -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                -- STABLE_SORT [$$t1.c2(ASC), $$p(ASC), $$n(DESC)]  |PARTITIONED|
+                                  -- HASH_PARTITION_EXCHANGE [$$t1.c2, $$p]  |PARTITIONED|
+                                    -- STREAM_PROJECT  |PARTITIONED|
+                                      -- UNNEST  |PARTITIONED|
+                                        -- UNNEST  |PARTITIONED|
+                                          -- UNNEST  |PARTITIONED|
+                                            -- STREAM_PROJECT  |PARTITIONED|
+                                              -- ASSIGN  |PARTITIONED|
+                                                -- STREAM_PROJECT  |PARTITIONED|
+                                                  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                    -- DATASOURCE_SCAN  |PARTITIONED|
+                                                      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                                        -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/window_02.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_misc/win_misc_02.plan
similarity index 100%
rename from asterixdb/asterix-app/src/test/resources/optimizerts/results/window/window_02.plan
rename to asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_misc/win_misc_02.plan
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_1.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_1.plan
new file mode 100644
index 0000000..871ea8e
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_1.plan
@@ -0,0 +1,11 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+          -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+            -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- UNNEST  |UNPARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_2.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_2.plan
new file mode 100644
index 0000000..a131487
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_2.plan
@@ -0,0 +1,15 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+                {
+                  -- AGGREGATE  |LOCAL|
+                    -- NESTED_TUPLE_SOURCE  |LOCAL|
+                }
+          -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+            -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- UNNEST  |UNPARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_3.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_3.plan
new file mode 100644
index 0000000..a131487
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_3.plan
@@ -0,0 +1,15 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+                {
+                  -- AGGREGATE  |LOCAL|
+                    -- NESTED_TUPLE_SOURCE  |LOCAL|
+                }
+          -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+            -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- UNNEST  |UNPARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_4.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_4.plan
new file mode 100644
index 0000000..a131487
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_4.plan
@@ -0,0 +1,15 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+                {
+                  -- AGGREGATE  |LOCAL|
+                    -- NESTED_TUPLE_SOURCE  |LOCAL|
+                }
+          -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+            -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- UNNEST  |UNPARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_5.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_5.plan
new file mode 100644
index 0000000..871ea8e
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_5.plan
@@ -0,0 +1,11 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+          -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+            -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                -- ASSIGN  |UNPARTITIONED|
+                  -- UNNEST  |UNPARTITIONED|
+                    -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_6.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_6.plan
new file mode 100644
index 0000000..ab78ecc
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_6.plan
@@ -0,0 +1,12 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- WINDOW  |LOCAL|
+          -- WINDOW  |LOCAL|
+            -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+              -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+                -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                  -- ASSIGN  |UNPARTITIONED|
+                    -- UNNEST  |UNPARTITIONED|
+                      -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_7.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_7.plan
new file mode 100644
index 0000000..5b3d480
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/win_opt_01/win_opt_01_7.plan
@@ -0,0 +1,17 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- STREAM_PROJECT  |LOCAL|
+          -- WINDOW  |LOCAL|
+                  {
+                    -- AGGREGATE  |LOCAL|
+                      -- NESTED_TUPLE_SOURCE  |LOCAL|
+                  }
+            -- WINDOW  |LOCAL|
+              -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                -- STABLE_SORT [$$m(ASC), $$t(ASC)]  |LOCAL|
+                  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                    -- ASSIGN  |UNPARTITIONED|
+                      -- UNNEST  |UNPARTITIONED|
+                        -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/window_01.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/window_01.plan
deleted file mode 100644
index 91e9cfc..0000000
--- a/asterixdb/asterix-app/src/test/resources/optimizerts/results/window/window_01.plan
+++ /dev/null
@@ -1,30 +0,0 @@
--- DISTRIBUTE_RESULT  |UNPARTITIONED|
-  -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
-    -- STREAM_PROJECT  |UNPARTITIONED|
-      -- ASSIGN  |UNPARTITIONED|
-        -- AGGREGATE  |UNPARTITIONED|
-          -- RANDOM_MERGE_EXCHANGE  |PARTITIONED|
-            -- AGGREGATE  |PARTITIONED|
-              -- STREAM_PROJECT  |PARTITIONED|
-                -- ASSIGN  |PARTITIONED|
-                  -- STREAM_PROJECT  |PARTITIONED|
-                    -- ASSIGN  |PARTITIONED|
-                      -- STREAM_PROJECT  |PARTITIONED|
-                        -- ASSIGN  |PARTITIONED|
-                          -- STREAM_PROJECT  |PARTITIONED|
-                            -- WINDOW  |PARTITIONED|
-                              -- WINDOW  |PARTITIONED|
-                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
-                                  -- STABLE_SORT [$$t1.c2(ASC), $$p(ASC), $$n(DESC)]  |PARTITIONED|
-                                    -- HASH_PARTITION_EXCHANGE [$$t1.c2, $$p]  |PARTITIONED|
-                                      -- STREAM_PROJECT  |PARTITIONED|
-                                        -- UNNEST  |PARTITIONED|
-                                          -- UNNEST  |PARTITIONED|
-                                            -- UNNEST  |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/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/misc_01/misc_01.7.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/misc_01/misc_01.7.query.sqlpp
new file mode 100644
index 0000000..a04ab08
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/misc_01/misc_01.7.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window function distinct aggregate
+ * Expected Res : SUCCESS
+ */
+
+SELECT m, t,
+  sum(t % 4) over (partition by m order by t rows between unbounded preceding and current row) as `sum`,
+  sum(distinct t % 4) over (partition by m order by t rows between unbounded preceding and current row) as `sum_distinct`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.1.query.sqlpp
new file mode 100644
index 0000000..d53d092
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.1.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of two running aggregates
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  round_half_to_even(percent_rank() over (partition by m order by t), 2)  as `percent_rank`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.2.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.2.query.sqlpp
new file mode 100644
index 0000000..c403726
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.2.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate and one regular aggregate
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t) over (partition by m order by t) as `sum`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.3.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.3.query.sqlpp
new file mode 100644
index 0000000..25d559d
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.3.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate
+ *                and one regular aggregate with complex argument
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t + m) over (partition by m order by t) as `sum`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.4.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.4.query.sqlpp
new file mode 100644
index 0000000..06f5ac3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.4.query.sqlpp
@@ -0,0 +1,31 @@
+/*
+ * 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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of one running aggregate and
+ *                two regular aggregates with complex arguments
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t,
+  row_number() over (partition by m order by t) as `row_nubmer`,
+  sum(t + m) over (partition by m order by t) as `sum`,
+  round_half_to_even(avg(t - m) over (partition by m order by t), 2) as `avg`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.5.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.5.query.sqlpp
new file mode 100644
index 0000000..b6bfd66
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.5.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of two window functions in LET clauses
+ * Expected Res : SUCCESS (one window operator in the optimized plan)
+ */
+
+SELECT m, t, row_number, ntile
+FROM range(1, 16) t
+LET m = t % 4,
+    row_number = row_number() over (partition by m order by t),
+    ntile = ntile(2) over (partition by m order by t)
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.6.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.6.query.sqlpp
new file mode 100644
index 0000000..0019ba8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.6.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of data dependency between two window functions.
+ *                No operator consolidation in this case.
+ * Expected Res : SUCCESS (two window operators in the optimized plan)
+ */
+
+SELECT m, t, row_number, ntile
+FROM range(1, 16) t
+LET m = t % 4,
+    row_number = row_number() over (partition by m order by t),
+    ntile = ntile(row_number + 1) over (partition by m order by t)
+ORDER BY m, t;
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.7.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.7.query.sqlpp
new file mode 100644
index 0000000..f139ab8
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/window/win_opt_01/win_opt_01.7.query.sqlpp
@@ -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.
+ */
+/*
+ * Description  : Test window operator consolidation rule handling of ROW frame mode
+ * Expected Res : SUCCESS (two window operators in the optimized plan)
+ */
+
+SELECT m, t,
+  sum(t) over (partition by m order by t rows between unbounded preceding and current row) as `sum`,
+  round_half_to_even(avg(t) over (partition by m order by t rows between unbounded preceding and current row), 2) as `avg`
+FROM range(1, 20) t
+LET m = t % 4
+ORDER BY m, t;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/misc_01/misc_01.7.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/misc_01/misc_01.7.adm
new file mode 100644
index 0000000..9deb329
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/misc_01/misc_01.7.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "sum": 0, "sum_distinct": 0 }
+{ "m": 0, "t": 8, "sum": 0, "sum_distinct": 0 }
+{ "m": 0, "t": 12, "sum": 0, "sum_distinct": 0 }
+{ "m": 0, "t": 16, "sum": 0, "sum_distinct": 0 }
+{ "m": 0, "t": 20, "sum": 0, "sum_distinct": 0 }
+{ "m": 1, "t": 1, "sum": 1, "sum_distinct": 1 }
+{ "m": 1, "t": 5, "sum": 2, "sum_distinct": 1 }
+{ "m": 1, "t": 9, "sum": 3, "sum_distinct": 1 }
+{ "m": 1, "t": 13, "sum": 4, "sum_distinct": 1 }
+{ "m": 1, "t": 17, "sum": 5, "sum_distinct": 1 }
+{ "m": 2, "t": 2, "sum": 2, "sum_distinct": 2 }
+{ "m": 2, "t": 6, "sum": 4, "sum_distinct": 2 }
+{ "m": 2, "t": 10, "sum": 6, "sum_distinct": 2 }
+{ "m": 2, "t": 14, "sum": 8, "sum_distinct": 2 }
+{ "m": 2, "t": 18, "sum": 10, "sum_distinct": 2 }
+{ "m": 3, "t": 3, "sum": 3, "sum_distinct": 3 }
+{ "m": 3, "t": 7, "sum": 6, "sum_distinct": 3 }
+{ "m": 3, "t": 11, "sum": 9, "sum_distinct": 3 }
+{ "m": 3, "t": 15, "sum": 12, "sum_distinct": 3 }
+{ "m": 3, "t": 19, "sum": 15, "sum_distinct": 3 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.1.adm
new file mode 100644
index 0000000..75263ed
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.1.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "row_nubmer": 1, "percent_rank": 0.0 }
+{ "m": 0, "t": 8, "row_nubmer": 2, "percent_rank": 0.25 }
+{ "m": 0, "t": 12, "row_nubmer": 3, "percent_rank": 0.5 }
+{ "m": 0, "t": 16, "row_nubmer": 4, "percent_rank": 0.75 }
+{ "m": 0, "t": 20, "row_nubmer": 5, "percent_rank": 1.0 }
+{ "m": 1, "t": 1, "row_nubmer": 1, "percent_rank": 0.0 }
+{ "m": 1, "t": 5, "row_nubmer": 2, "percent_rank": 0.25 }
+{ "m": 1, "t": 9, "row_nubmer": 3, "percent_rank": 0.5 }
+{ "m": 1, "t": 13, "row_nubmer": 4, "percent_rank": 0.75 }
+{ "m": 1, "t": 17, "row_nubmer": 5, "percent_rank": 1.0 }
+{ "m": 2, "t": 2, "row_nubmer": 1, "percent_rank": 0.0 }
+{ "m": 2, "t": 6, "row_nubmer": 2, "percent_rank": 0.25 }
+{ "m": 2, "t": 10, "row_nubmer": 3, "percent_rank": 0.5 }
+{ "m": 2, "t": 14, "row_nubmer": 4, "percent_rank": 0.75 }
+{ "m": 2, "t": 18, "row_nubmer": 5, "percent_rank": 1.0 }
+{ "m": 3, "t": 3, "row_nubmer": 1, "percent_rank": 0.0 }
+{ "m": 3, "t": 7, "row_nubmer": 2, "percent_rank": 0.25 }
+{ "m": 3, "t": 11, "row_nubmer": 3, "percent_rank": 0.5 }
+{ "m": 3, "t": 15, "row_nubmer": 4, "percent_rank": 0.75 }
+{ "m": 3, "t": 19, "row_nubmer": 5, "percent_rank": 1.0 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.2.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.2.adm
new file mode 100644
index 0000000..a08ac96
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.2.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "row_nubmer": 1, "sum": 4 }
+{ "m": 0, "t": 8, "row_nubmer": 2, "sum": 12 }
+{ "m": 0, "t": 12, "row_nubmer": 3, "sum": 24 }
+{ "m": 0, "t": 16, "row_nubmer": 4, "sum": 40 }
+{ "m": 0, "t": 20, "row_nubmer": 5, "sum": 60 }
+{ "m": 1, "t": 1, "row_nubmer": 1, "sum": 1 }
+{ "m": 1, "t": 5, "row_nubmer": 2, "sum": 6 }
+{ "m": 1, "t": 9, "row_nubmer": 3, "sum": 15 }
+{ "m": 1, "t": 13, "row_nubmer": 4, "sum": 28 }
+{ "m": 1, "t": 17, "row_nubmer": 5, "sum": 45 }
+{ "m": 2, "t": 2, "row_nubmer": 1, "sum": 2 }
+{ "m": 2, "t": 6, "row_nubmer": 2, "sum": 8 }
+{ "m": 2, "t": 10, "row_nubmer": 3, "sum": 18 }
+{ "m": 2, "t": 14, "row_nubmer": 4, "sum": 32 }
+{ "m": 2, "t": 18, "row_nubmer": 5, "sum": 50 }
+{ "m": 3, "t": 3, "row_nubmer": 1, "sum": 3 }
+{ "m": 3, "t": 7, "row_nubmer": 2, "sum": 10 }
+{ "m": 3, "t": 11, "row_nubmer": 3, "sum": 21 }
+{ "m": 3, "t": 15, "row_nubmer": 4, "sum": 36 }
+{ "m": 3, "t": 19, "row_nubmer": 5, "sum": 55 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.3.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.3.adm
new file mode 100644
index 0000000..f356720
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.3.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "row_nubmer": 1, "sum": 4 }
+{ "m": 0, "t": 8, "row_nubmer": 2, "sum": 12 }
+{ "m": 0, "t": 12, "row_nubmer": 3, "sum": 24 }
+{ "m": 0, "t": 16, "row_nubmer": 4, "sum": 40 }
+{ "m": 0, "t": 20, "row_nubmer": 5, "sum": 60 }
+{ "m": 1, "t": 1, "row_nubmer": 1, "sum": 2 }
+{ "m": 1, "t": 5, "row_nubmer": 2, "sum": 8 }
+{ "m": 1, "t": 9, "row_nubmer": 3, "sum": 18 }
+{ "m": 1, "t": 13, "row_nubmer": 4, "sum": 32 }
+{ "m": 1, "t": 17, "row_nubmer": 5, "sum": 50 }
+{ "m": 2, "t": 2, "row_nubmer": 1, "sum": 4 }
+{ "m": 2, "t": 6, "row_nubmer": 2, "sum": 12 }
+{ "m": 2, "t": 10, "row_nubmer": 3, "sum": 24 }
+{ "m": 2, "t": 14, "row_nubmer": 4, "sum": 40 }
+{ "m": 2, "t": 18, "row_nubmer": 5, "sum": 60 }
+{ "m": 3, "t": 3, "row_nubmer": 1, "sum": 6 }
+{ "m": 3, "t": 7, "row_nubmer": 2, "sum": 16 }
+{ "m": 3, "t": 11, "row_nubmer": 3, "sum": 30 }
+{ "m": 3, "t": 15, "row_nubmer": 4, "sum": 48 }
+{ "m": 3, "t": 19, "row_nubmer": 5, "sum": 70 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.4.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.4.adm
new file mode 100644
index 0000000..e14d3a2
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.4.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "row_nubmer": 1, "sum": 4, "avg": 4.0 }
+{ "m": 0, "t": 8, "row_nubmer": 2, "sum": 12, "avg": 6.0 }
+{ "m": 0, "t": 12, "row_nubmer": 3, "sum": 24, "avg": 8.0 }
+{ "m": 0, "t": 16, "row_nubmer": 4, "sum": 40, "avg": 10.0 }
+{ "m": 0, "t": 20, "row_nubmer": 5, "sum": 60, "avg": 12.0 }
+{ "m": 1, "t": 1, "row_nubmer": 1, "sum": 2, "avg": 0.0 }
+{ "m": 1, "t": 5, "row_nubmer": 2, "sum": 8, "avg": 2.0 }
+{ "m": 1, "t": 9, "row_nubmer": 3, "sum": 18, "avg": 4.0 }
+{ "m": 1, "t": 13, "row_nubmer": 4, "sum": 32, "avg": 6.0 }
+{ "m": 1, "t": 17, "row_nubmer": 5, "sum": 50, "avg": 8.0 }
+{ "m": 2, "t": 2, "row_nubmer": 1, "sum": 4, "avg": 0.0 }
+{ "m": 2, "t": 6, "row_nubmer": 2, "sum": 12, "avg": 2.0 }
+{ "m": 2, "t": 10, "row_nubmer": 3, "sum": 24, "avg": 4.0 }
+{ "m": 2, "t": 14, "row_nubmer": 4, "sum": 40, "avg": 6.0 }
+{ "m": 2, "t": 18, "row_nubmer": 5, "sum": 60, "avg": 8.0 }
+{ "m": 3, "t": 3, "row_nubmer": 1, "sum": 6, "avg": 0.0 }
+{ "m": 3, "t": 7, "row_nubmer": 2, "sum": 16, "avg": 2.0 }
+{ "m": 3, "t": 11, "row_nubmer": 3, "sum": 30, "avg": 4.0 }
+{ "m": 3, "t": 15, "row_nubmer": 4, "sum": 48, "avg": 6.0 }
+{ "m": 3, "t": 19, "row_nubmer": 5, "sum": 70, "avg": 8.0 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.5.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.5.adm
new file mode 100644
index 0000000..fa8f4af
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.5.adm
@@ -0,0 +1,16 @@
+{ "m": 0, "t": 4, "row_number": 1, "ntile": 1 }
+{ "m": 0, "t": 8, "row_number": 2, "ntile": 1 }
+{ "m": 0, "t": 12, "row_number": 3, "ntile": 2 }
+{ "m": 0, "t": 16, "row_number": 4, "ntile": 2 }
+{ "m": 1, "t": 1, "row_number": 1, "ntile": 1 }
+{ "m": 1, "t": 5, "row_number": 2, "ntile": 1 }
+{ "m": 1, "t": 9, "row_number": 3, "ntile": 2 }
+{ "m": 1, "t": 13, "row_number": 4, "ntile": 2 }
+{ "m": 2, "t": 2, "row_number": 1, "ntile": 1 }
+{ "m": 2, "t": 6, "row_number": 2, "ntile": 1 }
+{ "m": 2, "t": 10, "row_number": 3, "ntile": 2 }
+{ "m": 2, "t": 14, "row_number": 4, "ntile": 2 }
+{ "m": 3, "t": 3, "row_number": 1, "ntile": 1 }
+{ "m": 3, "t": 7, "row_number": 2, "ntile": 1 }
+{ "m": 3, "t": 11, "row_number": 3, "ntile": 2 }
+{ "m": 3, "t": 15, "row_number": 4, "ntile": 2 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.6.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.6.adm
new file mode 100644
index 0000000..fa8f4af
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.6.adm
@@ -0,0 +1,16 @@
+{ "m": 0, "t": 4, "row_number": 1, "ntile": 1 }
+{ "m": 0, "t": 8, "row_number": 2, "ntile": 1 }
+{ "m": 0, "t": 12, "row_number": 3, "ntile": 2 }
+{ "m": 0, "t": 16, "row_number": 4, "ntile": 2 }
+{ "m": 1, "t": 1, "row_number": 1, "ntile": 1 }
+{ "m": 1, "t": 5, "row_number": 2, "ntile": 1 }
+{ "m": 1, "t": 9, "row_number": 3, "ntile": 2 }
+{ "m": 1, "t": 13, "row_number": 4, "ntile": 2 }
+{ "m": 2, "t": 2, "row_number": 1, "ntile": 1 }
+{ "m": 2, "t": 6, "row_number": 2, "ntile": 1 }
+{ "m": 2, "t": 10, "row_number": 3, "ntile": 2 }
+{ "m": 2, "t": 14, "row_number": 4, "ntile": 2 }
+{ "m": 3, "t": 3, "row_number": 1, "ntile": 1 }
+{ "m": 3, "t": 7, "row_number": 2, "ntile": 1 }
+{ "m": 3, "t": 11, "row_number": 3, "ntile": 2 }
+{ "m": 3, "t": 15, "row_number": 4, "ntile": 2 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.7.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.7.adm
new file mode 100644
index 0000000..30ed6e2
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/window/win_opt_01/win_opt_01.7.adm
@@ -0,0 +1,20 @@
+{ "m": 0, "t": 4, "sum": 4, "avg": 4.0 }
+{ "m": 0, "t": 8, "sum": 12, "avg": 6.0 }
+{ "m": 0, "t": 12, "sum": 24, "avg": 8.0 }
+{ "m": 0, "t": 16, "sum": 40, "avg": 10.0 }
+{ "m": 0, "t": 20, "sum": 60, "avg": 12.0 }
+{ "m": 1, "t": 1, "sum": 1, "avg": 1.0 }
+{ "m": 1, "t": 5, "sum": 6, "avg": 3.0 }
+{ "m": 1, "t": 9, "sum": 15, "avg": 5.0 }
+{ "m": 1, "t": 13, "sum": 28, "avg": 7.0 }
+{ "m": 1, "t": 17, "sum": 45, "avg": 9.0 }
+{ "m": 2, "t": 2, "sum": 2, "avg": 2.0 }
+{ "m": 2, "t": 6, "sum": 8, "avg": 4.0 }
+{ "m": 2, "t": 10, "sum": 18, "avg": 6.0 }
+{ "m": 2, "t": 14, "sum": 32, "avg": 8.0 }
+{ "m": 2, "t": 18, "sum": 50, "avg": 10.0 }
+{ "m": 3, "t": 3, "sum": 3, "avg": 3.0 }
+{ "m": 3, "t": 7, "sum": 10, "avg": 5.0 }
+{ "m": 3, "t": 11, "sum": 21, "avg": 7.0 }
+{ "m": 3, "t": 15, "sum": 36, "avg": 9.0 }
+{ "m": 3, "t": 19, "sum": 55, "avg": 11.0 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results_parser_sqlpp/window/misc_01/misc_01.7.ast b/asterixdb/asterix-app/src/test/resources/runtimets/results_parser_sqlpp/window/misc_01/misc_01.7.ast
new file mode 100644
index 0000000..2271af5
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results_parser_sqlpp/window/misc_01/misc_01.7.ast
@@ -0,0 +1,58 @@
+Query:
+SELECT [
+Variable [ Name=$m ]
+m
+Variable [ Name=$t ]
+t
+WINDOW null.sum@1[
+  OperatorExpr [
+    Variable [ Name=$t ]
+    mod
+    LiteralExpr [LONG] [4]
+  ]
+]
+OVER (
+  PARTITION BY
+    Variable [ Name=$m ]
+  ORDER BY
+    Variable [ Name=$t ]
+    ASC
+  rows between unbounded preceding and current row exclude no others
+)
+sum
+WINDOW null.sum-distinct@1[
+  OperatorExpr [
+    Variable [ Name=$t ]
+    mod
+    LiteralExpr [LONG] [4]
+  ]
+]
+OVER (
+  PARTITION BY
+    Variable [ Name=$m ]
+  ORDER BY
+    Variable [ Name=$t ]
+    ASC
+  rows between unbounded preceding and current row exclude no others
+)
+sum_distinct
+]
+FROM [  FunctionCall null.range@2[
+    LiteralExpr [LONG] [1]
+    LiteralExpr [LONG] [20]
+  ]
+  AS Variable [ Name=$t ]
+]
+Let Variable [ Name=$m ]
+  :=
+  OperatorExpr [
+    Variable [ Name=$t ]
+    mod
+    LiteralExpr [LONG] [4]
+  ]
+Orderby
+  Variable [ Name=$m ]
+  ASC
+  Variable [ Name=$t ]
+  ASC
+
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
index 7bd1eaf..3a857c1 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -9260,6 +9260,11 @@
         <output-dir compare="Text">row_number_01</output-dir>
       </compilation-unit>
     </test-case>
+    <test-case FilePath="window">
+      <compilation-unit name="win_opt_01">
+        <output-dir compare="Text">win_opt_01</output-dir>
+      </compilation-unit>
+    </test-case>
   </test-group>
   <test-group name="writers">
     <test-case FilePath="writers">
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppDistinctAggregationSugarVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppDistinctAggregationSugarVisitor.java
index 80844ab..efcd7e0 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppDistinctAggregationSugarVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppDistinctAggregationSugarVisitor.java
@@ -38,6 +38,7 @@
 import org.apache.asterix.lang.sqlpp.clause.SelectElement;
 import org.apache.asterix.lang.sqlpp.clause.SelectSetOperation;
 import org.apache.asterix.lang.sqlpp.expression.SelectExpression;
+import org.apache.asterix.lang.sqlpp.expression.WindowExpression;
 import org.apache.asterix.lang.sqlpp.struct.SetOperationInput;
 import org.apache.asterix.lang.sqlpp.visitor.base.AbstractSqlppSimpleExpressionVisitor;
 import org.apache.asterix.om.functions.BuiltinFunctions;
@@ -59,25 +60,45 @@
 
     @Override
     public Expression visit(CallExpr callExpr, ILangExpression arg) throws CompilationException {
-        FunctionSignature signature = callExpr.getFunctionSignature();
-        IFunctionInfo finfo = FunctionUtil.getFunctionInfo(signature);
-        FunctionIdentifier aggFn =
-                finfo != null ? BuiltinFunctions.getAggregateFunction(finfo.getFunctionIdentifier()) : null;
-        FunctionIdentifier newAggFn = aggFn != null ? BuiltinFunctions.getAggregateFunctionForDistinct(aggFn) : null;
+        FunctionIdentifier newAggFn = getAggregateFunctionForDistinct(callExpr.getFunctionSignature());
         if (newAggFn == null) {
             return super.visit(callExpr, arg);
         }
-        List<Expression> exprList = callExpr.getExprList();
-        List<Expression> newExprList = new ArrayList<>(exprList.size());
-        for (Expression expr : exprList) {
-            Expression newExpr = rewriteArgument(expr);
-            newExprList.add(newExpr.accept(this, arg));
-        }
+        List<Expression> newExprList = rewriteArgumentList(callExpr.getExprList(), arg);
         callExpr.setFunctionSignature(new FunctionSignature(newAggFn));
         callExpr.setExprList(newExprList);
         return callExpr;
     }
 
+    @Override
+    public Expression visit(WindowExpression winExpr, ILangExpression arg) throws CompilationException {
+        FunctionIdentifier newAggFn = getAggregateFunctionForDistinct(winExpr.getFunctionSignature());
+        if (newAggFn == null) {
+            return super.visit(winExpr, arg);
+        }
+        List<Expression> newExprList = rewriteArgumentList(winExpr.getExprList(), arg);
+        winExpr.setFunctionSignature(new FunctionSignature(newAggFn));
+        winExpr.setExprList(newExprList);
+        return winExpr;
+    }
+
+    private FunctionIdentifier getAggregateFunctionForDistinct(FunctionSignature signature) {
+        IFunctionInfo finfo = FunctionUtil.getFunctionInfo(signature);
+        FunctionIdentifier aggFn =
+                finfo != null ? BuiltinFunctions.getAggregateFunction(finfo.getFunctionIdentifier()) : null;
+        return aggFn != null ? BuiltinFunctions.getAggregateFunctionForDistinct(aggFn) : null;
+    }
+
+    private List<Expression> rewriteArgumentList(List<Expression> exprList, ILangExpression arg)
+            throws CompilationException {
+        List<Expression> result = new ArrayList<>(exprList.size());
+        for (Expression expr : exprList) {
+            Expression newExpr = rewriteArgument(expr);
+            result.add(newExpr.accept(this, arg));
+        }
+        return result;
+    }
+
     /**
      * rewrites {@code expr -> FROM expr AS i SELECT DISTINCT VALUE i}
      */
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/VariableCheckAndRewriteVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/VariableCheckAndRewriteVisitor.java
index b48e024..7ffebc2 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/VariableCheckAndRewriteVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/VariableCheckAndRewriteVisitor.java
@@ -204,6 +204,7 @@
         return path.length == 2 && metadataProvider.findDataset(path[0], path[1]) != null;
     }
 
+    @Override
     public Expression visit(CallExpr callExpr, ILangExpression arg) throws CompilationException {
         // skip variables inside SQL-92 aggregates (they will be resolved by SqlppGroupByAggregationSugarVisitor)
         if (FunctionMapUtil.isSql92AggregateFunction(callExpr.getFunctionSignature())) {
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/SqlppAstPrintVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/SqlppAstPrintVisitor.java
index f1039ff..d906a82 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/SqlppAstPrintVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/SqlppAstPrintVisitor.java
@@ -379,8 +379,8 @@
             }
         }
         if (winExpr.hasFrameDefinition()) {
-            out.println(skip(step + 1) + winExpr.getFrameMode() + ' ' + winExpr.getFrameStartKind() + ' '
-                    + winExpr.getFrameEndKind() + " EXCLUDE " + winExpr.getFrameExclusionKind());
+            out.println(skip(step + 1) + winExpr.getFrameMode() + " between " + winExpr.getFrameStartKind() + " and "
+                    + winExpr.getFrameEndKind() + " exclude " + winExpr.getFrameExclusionKind());
             if (winExpr.hasFrameStartExpr()) {
                 winExpr.getFrameStartExpr().accept(this, step + 2);
             }
diff --git a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
index 08f5139..54c8330 100644
--- a/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
+++ b/asterixdb/asterix-om/src/main/java/org/apache/asterix/om/functions/BuiltinFunctions.java
@@ -1790,9 +1790,9 @@
         addFunction(SCALAR_SQL_COUNT_DISTINCT, AInt64TypeComputer.INSTANCE, true);
 
         addFunction(SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
+        addFunction(SCALAR_SUM_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
         addFunction(SQL_SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
-        addFunction(SCALAR_SQL_SUM_DISTINCT, NumericSumAggTypeComputer.INSTANCE, true);
+        addFunction(SCALAR_SQL_SUM_DISTINCT, ScalarVersionOfAggregateResultType.INSTANCE, true);
 
         addFunction(AVG_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
         addFunction(SCALAR_AVG_DISTINCT, NullableDoubleTypeComputer.INSTANCE, true);
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/WindowOperator.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/WindowOperator.java
index e09b471..8f563b3 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/WindowOperator.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/WindowOperator.java
@@ -68,7 +68,7 @@
 
     private final List<Mutable<ILogicalExpression>> frameExcludeExpressions;
 
-    private final int frameExcludeNegationStartIdx;
+    private int frameExcludeNegationStartIdx;
 
     private final Mutable<ILogicalExpression> frameOffset;
 
@@ -175,6 +175,10 @@
         return frameExcludeNegationStartIdx;
     }
 
+    public void setFrameExcludeNegationStartIdx(int value) {
+        this.frameExcludeNegationStartIdx = value;
+    }
+
     public Mutable<ILogicalExpression> getFrameOffset() {
         return frameOffset;
     }
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
index 764fe49..a39af41 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismOperatorVisitor.java
@@ -624,32 +624,10 @@
             return false;
         }
         WindowOperator windowOpArg = (WindowOperator) copyAndSubstituteVar(op, arg);
-        if (!VariableUtilities.varListEqualUnordered(op.getPartitionExpressions(),
-                windowOpArg.getPartitionExpressions())) {
+        if (!compareWindowPartitionSpec(op, windowOpArg)) {
             return false;
         }
-        if (!compareIOrderAndExpressions(op.getOrderExpressions(), windowOpArg.getOrderExpressions())) {
-            return false;
-        }
-        if (!compareIOrderAndExpressions(op.getFrameValueExpressions(), windowOpArg.getFrameValueExpressions())) {
-            return false;
-        }
-        if (!compareExpressions(op.getFrameStartExpressions(), windowOpArg.getFrameStartExpressions())) {
-            return false;
-        }
-        if (!compareExpressions(op.getFrameEndExpressions(), windowOpArg.getFrameEndExpressions())) {
-            return false;
-        }
-        if (!compareExpressions(op.getFrameExcludeExpressions(), windowOpArg.getFrameExcludeExpressions())) {
-            return false;
-        }
-        if (op.getFrameExcludeNegationStartIdx() != windowOpArg.getFrameExcludeNegationStartIdx()) {
-            return false;
-        }
-        if (!Objects.equals(op.getFrameOffset().getValue(), windowOpArg.getFrameOffset().getValue())) {
-            return false;
-        }
-        if (op.getFrameMaxObjects() != windowOpArg.getFrameMaxObjects()) {
+        if (!compareWindowFrameSpec(op, windowOpArg)) {
             return false;
         }
         if (!VariableUtilities.varListEqualUnordered(getPairList(op.getVariables(), op.getExpressions()),
@@ -662,36 +640,52 @@
         return isomorphic;
     }
 
-    private Boolean compareExpressions(List<Mutable<ILogicalExpression>> opExprs,
+    public static boolean compareWindowPartitionSpec(WindowOperator winOp1, WindowOperator winOp2) {
+        return VariableUtilities.varListEqualUnordered(winOp1.getPartitionExpressions(),
+                winOp2.getPartitionExpressions())
+                && compareIOrderAndExpressions(winOp1.getOrderExpressions(), winOp2.getOrderExpressions());
+    }
+
+    public static boolean compareWindowFrameSpec(WindowOperator winOp1, WindowOperator winOp2) {
+        return compareIOrderAndExpressions(winOp1.getFrameValueExpressions(), winOp2.getFrameValueExpressions())
+                && compareExpressions(winOp1.getFrameStartExpressions(), winOp2.getFrameStartExpressions())
+                && compareExpressions(winOp1.getFrameEndExpressions(), winOp2.getFrameEndExpressions())
+                && compareExpressions(winOp1.getFrameExcludeExpressions(), winOp2.getFrameExcludeExpressions())
+                && winOp1.getFrameExcludeNegationStartIdx() == winOp2.getFrameExcludeNegationStartIdx()
+                && Objects.equals(winOp1.getFrameOffset().getValue(), winOp2.getFrameOffset().getValue())
+                && winOp1.getFrameMaxObjects() == winOp2.getFrameMaxObjects();
+    }
+
+    private static boolean compareExpressions(List<Mutable<ILogicalExpression>> opExprs,
             List<Mutable<ILogicalExpression>> argExprs) {
         if (opExprs.size() != argExprs.size()) {
-            return Boolean.FALSE;
+            return false;
         }
         for (int i = 0; i < opExprs.size(); i++) {
             boolean isomorphic = opExprs.get(i).getValue().equals(argExprs.get(i).getValue());
             if (!isomorphic) {
-                return Boolean.FALSE;
+                return false;
             }
         }
-        return Boolean.TRUE;
+        return true;
     }
 
-    private Boolean compareIOrderAndExpressions(List<Pair<IOrder, Mutable<ILogicalExpression>>> opOrderExprs,
+    private static boolean compareIOrderAndExpressions(List<Pair<IOrder, Mutable<ILogicalExpression>>> opOrderExprs,
             List<Pair<IOrder, Mutable<ILogicalExpression>>> argOrderExprs) {
         if (opOrderExprs.size() != argOrderExprs.size()) {
-            return Boolean.FALSE;
+            return false;
         }
         for (int i = 0; i < opOrderExprs.size(); i++) {
             boolean isomorphic = opOrderExprs.get(i).first.equals(argOrderExprs.get(i).first);
             if (!isomorphic) {
-                return Boolean.FALSE;
+                return false;
             }
             isomorphic = opOrderExprs.get(i).second.getValue().equals(argOrderExprs.get(i).second.getValue());
             if (!isomorphic) {
-                return Boolean.FALSE;
+                return false;
             }
         }
-        return Boolean.TRUE;
+        return true;
     }
 
     private boolean compareSubplans(List<ILogicalPlan> plans, List<ILogicalPlan> plansArg) throws AlgebricksException {
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
index 5591053..eca2508 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/operators/logical/visitors/IsomorphismVariableMappingVisitor.java
@@ -99,7 +99,7 @@
     @Override
     public Void visitWindowOperator(WindowOperator op, ILogicalOperator arg) throws AlgebricksException {
         mapChildren(op, arg);
-        mapVariablesForAbstractAssign(op, arg);
+        mapVariablesForWindow(op, arg);
         mapVariablesInNestedPlans(op, arg);
         return null;
     }
@@ -359,7 +359,7 @@
                 rightOp.getExpressions());
     }
 
-    private void mapVariablesForGroupBy(ILogicalOperator left, ILogicalOperator right) throws AlgebricksException {
+    private void mapVariablesForGroupBy(ILogicalOperator left, ILogicalOperator right) {
         if (left.getOperatorTag() != right.getOperatorTag()) {
             return;
         }
@@ -373,6 +373,16 @@
         mapVarExprPairList(leftPairs, rightPairs);
     }
 
+    private void mapVariablesForWindow(ILogicalOperator left, ILogicalOperator right) {
+        if (left.getOperatorTag() != right.getOperatorTag()) {
+            return;
+        }
+        WindowOperator leftOp = (WindowOperator) left;
+        WindowOperator rightOp = (WindowOperator) right;
+        mapVariablesForAbstractAssign(leftOp.getVariables(), leftOp.getExpressions(), rightOp.getVariables(),
+                rightOp.getExpressions());
+    }
+
     private void mapVarExprPairList(List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> leftPairs,
             List<Pair<LogicalVariable, Mutable<ILogicalExpression>>> rightPairs) {
         if (leftPairs.size() != rightPairs.size()) {
@@ -420,6 +430,9 @@
 
     private void mapVariablesInNestedPlans(AbstractOperatorWithNestedPlans op, ILogicalOperator arg)
             throws AlgebricksException {
+        if (op.getOperatorTag() != arg.getOperatorTag()) {
+            return;
+        }
         AbstractOperatorWithNestedPlans argOp = (AbstractOperatorWithNestedPlans) arg;
         List<ILogicalPlan> plans = op.getNestedPlans();
         List<ILogicalPlan> plansArg = argOp.getNestedPlans();
diff --git a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java
index 4d05a1b..967ad6f 100644
--- a/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java
+++ b/hyracks-fullstack/algebricks/algebricks-core/src/main/java/org/apache/hyracks/algebricks/core/algebra/util/OperatorManipulationUtil.java
@@ -36,6 +36,7 @@
 import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
 import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
@@ -407,4 +408,25 @@
         }
         return clonedExprList;
     }
+
+    /**
+     * Finds a variable assigned to a given expression and returns a new {@link VariableReferenceExpression}
+     * referring to this variable.
+     * @param assignVarList list of variables
+     * @param assignExprList list of expressions assigned to those variables
+     * @param searchExpr expression to search for
+     * @return said value, {@code null} if a variable is not found
+     */
+    public static VariableReferenceExpression findAssignedVariable(List<LogicalVariable> assignVarList,
+            List<Mutable<ILogicalExpression>> assignExprList, ILogicalExpression searchExpr) {
+        for (int i = 0, n = assignExprList.size(); i < n; i++) {
+            ILogicalExpression expr = assignExprList.get(i).getValue();
+            if (expr.equals(searchExpr)) {
+                VariableReferenceExpression result = new VariableReferenceExpression(assignVarList.get(i));
+                result.setSourceLocation(expr.getSourceLocation());
+                return result;
+            }
+        }
+        return null;
+    }
 }
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ConsolidateWindowOperatorsRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ConsolidateWindowOperatorsRule.java
new file mode 100644
index 0000000..61880a2
--- /dev/null
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ConsolidateWindowOperatorsRule.java
@@ -0,0 +1,155 @@
+/*
+ * 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.
+ */
+
+package org.apache.hyracks.algebricks.rewriter.rules;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalPlan;
+import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.WindowOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.IsomorphismOperatorVisitor;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.IsomorphismUtilities;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
+import org.apache.hyracks.algebricks.core.algebra.util.OperatorPropertiesUtil;
+import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * Merges two adjacent window operators into one if their window specifications are compatible.
+ * <pre>
+ * window [$x] <- [f()] with nested plan (aggergate [$a] <- [agg_1()] - ... - nts )
+ * window [$y] <- [g()] with nesedd plan (aggregate [$b] <- [agg_2()] - ... - nts )
+ * -->
+ * window [$x, $y] <- [f(), g()] with nested plan ( aggregate [$a, $b] <- [agg_1(), agg_2()] - ... - nts )
+ * </pre>
+ */
+public class ConsolidateWindowOperatorsRule implements IAlgebraicRewriteRule {
+
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op1 = (AbstractLogicalOperator) opRef.getValue();
+        if (op1.getOperatorTag() != LogicalOperatorTag.WINDOW) {
+            return false;
+        }
+        WindowOperator winOp1 = (WindowOperator) op1;
+
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op1.getInputs().get(0).getValue();
+        if (op2.getOperatorTag() != LogicalOperatorTag.WINDOW) {
+            return false;
+        }
+
+        WindowOperator winOp2 = (WindowOperator) op2;
+
+        if (!IsomorphismOperatorVisitor.compareWindowPartitionSpec(winOp1, winOp2)) {
+            return false;
+        }
+        if (winOp1.hasNestedPlans() && winOp2.hasNestedPlans()
+                && !IsomorphismOperatorVisitor.compareWindowFrameSpec(winOp1, winOp2)) {
+            return false;
+        }
+
+        Set<LogicalVariable> used1 = new HashSet<>();
+        VariableUtilities.getUsedVariables(winOp1, used1);
+        if (!OperatorPropertiesUtil.disjoint(winOp2.getVariables(), used1)) {
+            return false;
+        }
+
+        if (winOp2.hasNestedPlans() && !consolidateNestedPlans(winOp1, winOp2, context)) {
+            return false;
+        }
+
+        winOp1.getVariables().addAll(winOp2.getVariables());
+        winOp1.getExpressions().addAll(winOp2.getExpressions());
+
+        winOp1.getInputs().clear();
+        winOp1.getInputs().addAll(winOp2.getInputs());
+        context.computeAndSetTypeEnvironmentForOperator(winOp1);
+
+        return true;
+    }
+
+    private boolean consolidateNestedPlans(WindowOperator winOpTo, WindowOperator winOpFrom,
+            IOptimizationContext context) throws AlgebricksException {
+        if (winOpTo.hasNestedPlans()) {
+            AggregateOperator aggTo = getAggregateRoot(winOpTo.getNestedPlans());
+            if (aggTo == null) {
+                return false;
+            }
+            AggregateOperator aggFrom = getAggregateRoot(winOpFrom.getNestedPlans());
+            if (aggFrom == null) {
+                return false;
+            }
+            if (!IsomorphismUtilities.isOperatorIsomorphicPlanSegment(aggTo.getInputs().get(0).getValue(),
+                    aggFrom.getInputs().get(0).getValue())) {
+                return false;
+            }
+            aggTo.getVariables().addAll(aggFrom.getVariables());
+            aggTo.getExpressions().addAll(aggFrom.getExpressions());
+            context.computeAndSetTypeEnvironmentForOperator(aggTo);
+        } else {
+            setAll(winOpTo.getNestedPlans(), winOpFrom.getNestedPlans());
+            setAll(winOpTo.getFrameValueExpressions(), winOpFrom.getFrameValueExpressions());
+            setAll(winOpTo.getFrameStartExpressions(), winOpFrom.getFrameStartExpressions());
+            setAll(winOpTo.getFrameEndExpressions(), winOpFrom.getFrameEndExpressions());
+            setAll(winOpTo.getFrameExcludeExpressions(), winOpFrom.getFrameExcludeExpressions());
+            winOpTo.setFrameExcludeNegationStartIdx(winOpFrom.getFrameExcludeNegationStartIdx());
+            winOpTo.getFrameOffset().setValue(winOpFrom.getFrameOffset().getValue());
+            winOpTo.setFrameMaxObjects(winOpFrom.getFrameMaxObjects());
+        }
+        return true;
+    }
+
+    private AggregateOperator getAggregateRoot(List<ILogicalPlan> nestedPlans) {
+        if (nestedPlans.size() != 1) {
+            return null;
+        }
+        List<Mutable<ILogicalOperator>> roots = nestedPlans.get(0).getRoots();
+        if (roots.size() != 1) {
+            return null;
+        }
+        ILogicalOperator rootOp = roots.get(0).getValue();
+        if (rootOp.getOperatorTag() != LogicalOperatorTag.AGGREGATE) {
+            return null;
+        }
+        return (AggregateOperator) rootOp;
+    }
+
+    private <T> void setAll(Collection<? super T> to, Collection<? extends T> from) {
+        if (!to.isEmpty()) {
+            throw new IllegalStateException(String.valueOf(to.size()));
+        }
+        to.addAll(from);
+    }
+}
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineAssignIntoAggregateRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineAssignIntoAggregateRule.java
index d0dff03..a97c38b 100644
--- a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineAssignIntoAggregateRule.java
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineAssignIntoAggregateRule.java
@@ -34,9 +34,9 @@
 import org.apache.hyracks.algebricks.core.algebra.expressions.ConstantExpression;
 import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AggregateOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
-import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
 import org.apache.hyracks.algebricks.core.algebra.visitors.AbstractConstVarFunVisitor;
 import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
 
@@ -51,48 +51,71 @@
     public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
             throws AlgebricksException {
         AbstractLogicalOperator op = (AbstractLogicalOperator) opRef.getValue();
-        if (op.getOperatorTag() != LogicalOperatorTag.GROUP) {
+        if (op.getOperatorTag() != LogicalOperatorTag.GROUP && op.getOperatorTag() != LogicalOperatorTag.WINDOW) {
             return false;
         }
         boolean changed = false;
-        GroupByOperator gbyOp = (GroupByOperator) op;
-        for (ILogicalPlan p : gbyOp.getNestedPlans()) {
+        AbstractOperatorWithNestedPlans opWithNestedPlan = (AbstractOperatorWithNestedPlans) op;
+        for (ILogicalPlan p : opWithNestedPlan.getNestedPlans()) {
             for (Mutable<ILogicalOperator> r : p.getRoots()) {
-                if (inlined(r)) {
-                    changed = true;
-                }
+                changed |= inlined(r.getValue(), opWithNestedPlan);
             }
         }
         return changed;
     }
 
-    private boolean inlined(Mutable<ILogicalOperator> r) throws AlgebricksException {
-        AbstractLogicalOperator op1 = (AbstractLogicalOperator) r.getValue();
+    private boolean inlined(ILogicalOperator planRootOp, AbstractOperatorWithNestedPlans opWithNestedPlan)
+            throws AlgebricksException {
+        AbstractLogicalOperator op1 = (AbstractLogicalOperator) planRootOp;
         if (op1.getOperatorTag() != LogicalOperatorTag.AGGREGATE) {
             return false;
         }
-        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op1.getInputs().get(0).getValue();
+        AggregateOperator aggOp = (AggregateOperator) op1;
+        boolean inlined = inlineInputAssignIntoAgg(aggOp);
+        if (opWithNestedPlan.getOperatorTag() == LogicalOperatorTag.WINDOW) {
+            inlined |= inlineOuterInputAssignIntoAgg(aggOp, opWithNestedPlan);
+        }
+        return inlined;
+    }
+
+    private boolean inlineInputAssignIntoAgg(AggregateOperator aggOp) throws AlgebricksException {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) aggOp.getInputs().get(0).getValue();
         if (op2.getOperatorTag() != LogicalOperatorTag.ASSIGN) {
             return false;
         }
-        AggregateOperator agg = (AggregateOperator) op1;
-        AssignOperator assign = (AssignOperator) op2;
-        VarExprSubstitution ves = new VarExprSubstitution(assign.getVariables(), assign.getExpressions());
-        for (Mutable<ILogicalExpression> exprRef : agg.getExpressions()) {
-            ILogicalExpression expr = exprRef.getValue();
-            Pair<Boolean, ILogicalExpression> p = expr.accept(ves, null);
-            if (p.first == true) {
-                exprRef.setValue(p.second);
-            }
-            // AbstractLogicalExpression ale = (AbstractLogicalExpression) expr;
-            // ale.accept(ves, null);
-        }
-        List<Mutable<ILogicalOperator>> op1InpList = op1.getInputs();
+        AssignOperator assignOp = (AssignOperator) op2;
+        VarExprSubstitution ves = new VarExprSubstitution(assignOp.getVariables(), assignOp.getExpressions());
+        inlineVariables(aggOp, ves);
+        List<Mutable<ILogicalOperator>> op1InpList = aggOp.getInputs();
         op1InpList.clear();
         op1InpList.add(op2.getInputs().get(0));
         return true;
     }
 
+    private boolean inlineOuterInputAssignIntoAgg(AggregateOperator aggOp,
+            AbstractOperatorWithNestedPlans opWithNestedPlans) throws AlgebricksException {
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) opWithNestedPlans.getInputs().get(0).getValue();
+        if (op2.getOperatorTag() != LogicalOperatorTag.ASSIGN) {
+            return false;
+        }
+        AssignOperator assignOp = (AssignOperator) op2;
+        VarExprSubstitution ves = new VarExprSubstitution(assignOp.getVariables(), assignOp.getExpressions());
+        return inlineVariables(aggOp, ves);
+    }
+
+    private boolean inlineVariables(AggregateOperator aggOp, VarExprSubstitution ves) throws AlgebricksException {
+        boolean inlined = false;
+        for (Mutable<ILogicalExpression> exprRef : aggOp.getExpressions()) {
+            ILogicalExpression expr = exprRef.getValue();
+            Pair<Boolean, ILogicalExpression> p = expr.accept(ves, null);
+            if (p.first) {
+                exprRef.setValue(p.second);
+                inlined = true;
+            }
+        }
+        return inlined;
+    }
+
     private class VarExprSubstitution extends AbstractConstVarFunVisitor<Pair<Boolean, ILogicalExpression>, Void> {
 
         private List<LogicalVariable> variables;
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
index 5d6237a..729d6f9 100644
--- a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/InlineVariablesRule.java
@@ -39,8 +39,8 @@
 import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
 import org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractOperatorWithNestedPlans;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
-import org.apache.hyracks.algebricks.core.algebra.operators.logical.SubplanOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.VariableUtilities;
 import org.apache.hyracks.algebricks.core.algebra.visitors.ILogicalExpressionReferenceTransform;
 import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
@@ -157,9 +157,9 @@
         }
 
         // Descend into subplan
-        if (op.getOperatorTag() == LogicalOperatorTag.SUBPLAN) {
-            SubplanOperator subplanOp = (SubplanOperator) op;
-            for (ILogicalPlan nestedPlan : subplanOp.getNestedPlans()) {
+        if (op.getOperatorTag() == LogicalOperatorTag.SUBPLAN || op.getOperatorTag() == LogicalOperatorTag.WINDOW) {
+            List<ILogicalPlan> nestedPlans = ((AbstractOperatorWithNestedPlans) op).getNestedPlans();
+            for (ILogicalPlan nestedPlan : nestedPlans) {
                 for (Mutable<ILogicalOperator> root : nestedPlan.getRoots()) {
                     if (inlineVariables(root, context)) {
                         modified = true;
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ReuseWindowAggregateRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ReuseWindowAggregateRule.java
new file mode 100644
index 0000000..59272ec
--- /dev/null
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/ReuseWindowAggregateRule.java
@@ -0,0 +1,119 @@
+/*
+ * 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.
+ */
+
+package org.apache.hyracks.algebricks.rewriter.rules;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.apache.commons.lang3.mutable.Mutable;
+import org.apache.commons.lang3.mutable.MutableObject;
+import org.apache.hyracks.algebricks.common.exceptions.AlgebricksException;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalExpression;
+import org.apache.hyracks.algebricks.core.algebra.base.ILogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.base.IOptimizationContext;
+import org.apache.hyracks.algebricks.core.algebra.base.LogicalOperatorTag;
+import org.apache.hyracks.algebricks.core.algebra.base.LogicalVariable;
+import org.apache.hyracks.algebricks.core.algebra.expressions.VariableReferenceExpression;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AbstractLogicalOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.AssignOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.WindowOperator;
+import org.apache.hyracks.algebricks.core.algebra.operators.logical.visitors.IsomorphismOperatorVisitor;
+import org.apache.hyracks.algebricks.core.algebra.util.OperatorManipulationUtil;
+import org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * If two adjacent window operators compute the same running aggregate then replace the second computation with
+ * the assign operator referring to the first operator's output variable:
+ *
+ * <pre>
+ * window [$x] <- [f()] ...
+ * window [$y] <- [f()] ...
+ * -->
+ * assign [$x] <- [$y]
+ * window [] <- [] ...
+ * window [$y] <- [f()] ...
+ * </pre>
+ *
+ * Both window operators must have the same partitioning specification.
+ *
+ * This rule must be followed by {@link RemoveRedundantVariablesRule} to substitute {@code $x} references with
+ * {@code $y} and then {@link RemoveUnusedAssignAndAggregateRule} to eliminate the new assign operator.
+ */
+public class ReuseWindowAggregateRule implements IAlgebraicRewriteRule {
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context) {
+        return false;
+    }
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op1 = (AbstractLogicalOperator) opRef.getValue();
+        if (op1.getOperatorTag() != LogicalOperatorTag.WINDOW) {
+            return false;
+        }
+        WindowOperator winOp1 = (WindowOperator) op1;
+
+        AbstractLogicalOperator op2 = (AbstractLogicalOperator) op1.getInputs().get(0).getValue();
+        if (op2.getOperatorTag() != LogicalOperatorTag.WINDOW) {
+            return false;
+        }
+
+        WindowOperator winOp2 = (WindowOperator) op2;
+
+        if (!IsomorphismOperatorVisitor.compareWindowPartitionSpec(winOp1, winOp2)) {
+            return false;
+        }
+
+        List<LogicalVariable> assignVars = new ArrayList<>();
+        List<Mutable<ILogicalExpression>> assignExprs = new ArrayList<>();
+
+        List<LogicalVariable> varsOp1 = winOp1.getVariables();
+        List<LogicalVariable> varsOp2 = winOp2.getVariables();
+        List<Mutable<ILogicalExpression>> exprsOp1 = winOp1.getExpressions();
+        List<Mutable<ILogicalExpression>> exprsOp2 = winOp2.getExpressions();
+        Iterator<LogicalVariable> varsOp1Iter = varsOp1.iterator();
+        Iterator<Mutable<ILogicalExpression>> exprsOp1Iter = exprsOp1.iterator();
+        while (varsOp1Iter.hasNext()) {
+            LogicalVariable varOp1 = varsOp1Iter.next();
+            Mutable<ILogicalExpression> exprOp1 = exprsOp1Iter.next();
+            VariableReferenceExpression varOp2Ref =
+                    OperatorManipulationUtil.findAssignedVariable(varsOp2, exprsOp2, exprOp1.getValue());
+            if (varOp2Ref != null) {
+                varsOp1Iter.remove();
+                exprsOp1Iter.remove();
+                assignVars.add(varOp1);
+                assignExprs.add(new MutableObject<>(varOp2Ref));
+            }
+        }
+
+        if (assignVars.isEmpty()) {
+            return false;
+        }
+
+        AssignOperator assignOp = new AssignOperator(assignVars, assignExprs);
+        assignOp.getInputs().add(new MutableObject<>(winOp1));
+        assignOp.setSourceLocation(winOp1.getSourceLocation());
+        context.computeAndSetTypeEnvironmentForOperator(assignOp);
+        opRef.setValue(assignOp);
+        return true;
+    }
+}
\ No newline at end of file