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 31be802..1dd5e9c 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
@@ -135,6 +135,7 @@
 import org.apache.hyracks.algebricks.rewriter.rules.SetExecutionModeRule;
 import org.apache.hyracks.algebricks.rewriter.rules.SimpleUnnestToProductRule;
 import org.apache.hyracks.algebricks.rewriter.rules.SwitchInnerJoinBranchRule;
+import org.apache.hyracks.algebricks.rewriter.rules.subplan.EliminateIsomorphicSubplanRule;
 import org.apache.hyracks.algebricks.rewriter.rules.subplan.EliminateSubplanRule;
 import org.apache.hyracks.algebricks.rewriter.rules.subplan.EliminateSubplanWithInputCardinalityOneRule;
 import org.apache.hyracks.algebricks.rewriter.rules.subplan.NestedSubplanToJoinRule;
@@ -224,6 +225,10 @@
         condPushDownAndJoinInference.add(new PushMapOperatorDownThroughProductRule());
         condPushDownAndJoinInference.add(new PushSubplanWithAggregateDownThroughProductRule());
         condPushDownAndJoinInference.add(new SubplanOutOfGroupRule());
+        // The following rule must run before PushAggregateIntoNestedSubplanRule
+        // (before common subplans diverge due to aggregate pushdown)
+        condPushDownAndJoinInference.add(new EliminateIsomorphicSubplanRule());
+
         condPushDownAndJoinInference.add(new AsterixExtractFunctionsFromJoinConditionRule());
 
         condPushDownAndJoinInference.add(new RemoveRedundantVariablesRule());
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/group-by/listify-3.1.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/group-by/listify-3.1.sqlpp
new file mode 100644
index 0000000..b15c3b3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/group-by/listify-3.1.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.
+ */
+
+WITH info AS (
+  SELECT avg(t) AS mean, min(t) AS min
+  FROM range(1, 10) t
+)[0]
+
+SELECT round_half_to_even(sqrt(avg(square)), 2) std
+FROM (
+  SELECT VALUE power(info.mean - t + info.min - 1, 2)
+  FROM range(1, 10) t
+) square;
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/group-by/listify-3.1.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/group-by/listify-3.1.plan
new file mode 100644
index 0000000..85fa62d
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/group-by/listify-3.1.plan
@@ -0,0 +1,43 @@
+-- DISTRIBUTE_RESULT  |LOCAL|
+  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+    -- STREAM_PROJECT  |LOCAL|
+      -- ASSIGN  |LOCAL|
+        -- AGGREGATE  |LOCAL|
+          -- AGGREGATE  |LOCAL|
+            -- STREAM_PROJECT  |LOCAL|
+              -- ASSIGN  |LOCAL|
+                -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                  -- NESTED_LOOP  |LOCAL|
+                    -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                      -- NESTED_LOOP  |LOCAL|
+                        -- ONE_TO_ONE_EXCHANGE  |UNPARTITIONED|
+                          -- UNNEST  |UNPARTITIONED|
+                            -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                          -- STREAM_PROJECT  |LOCAL|
+                            -- ASSIGN  |LOCAL|
+                              -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                                -- REPLICATE  |LOCAL|
+                                  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                                    -- AGGREGATE  |LOCAL|
+                                      -- STREAM_PROJECT  |LOCAL|
+                                        -- ASSIGN  |LOCAL|
+                                          -- AGGREGATE  |LOCAL|
+                                            -- AGGREGATE  |LOCAL|
+                                              -- UNNEST  |UNPARTITIONED|
+                                                -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                      -- STREAM_PROJECT  |LOCAL|
+                        -- ASSIGN  |LOCAL|
+                          -- STREAM_PROJECT  |LOCAL|
+                            -- ASSIGN  |LOCAL|
+                              -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                                -- REPLICATE  |LOCAL|
+                                  -- ONE_TO_ONE_EXCHANGE  |LOCAL|
+                                    -- AGGREGATE  |LOCAL|
+                                      -- STREAM_PROJECT  |LOCAL|
+                                        -- ASSIGN  |LOCAL|
+                                          -- AGGREGATE  |LOCAL|
+                                            -- AGGREGATE  |LOCAL|
+                                              -- UNNEST  |UNPARTITIONED|
+                                                -- EMPTY_TUPLE_SOURCE  |UNPARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/listify-3/listify-3.1.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/listify-3/listify-3.1.query.sqlpp
new file mode 100644
index 0000000..b15c3b3
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/group-by/listify-3/listify-3.1.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.
+ */
+
+WITH info AS (
+  SELECT avg(t) AS mean, min(t) AS min
+  FROM range(1, 10) t
+)[0]
+
+SELECT round_half_to_even(sqrt(avg(square)), 2) std
+FROM (
+  SELECT VALUE power(info.mean - t + info.min - 1, 2)
+  FROM range(1, 10) t
+) square;
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/group-by/listify-3/listify-3.1.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/group-by/listify-3/listify-3.1.adm
new file mode 100644
index 0000000..5be6793
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/group-by/listify-3/listify-3.1.adm
@@ -0,0 +1 @@
+{ "std": 2.87 }
\ No newline at end of file
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 b39c2f8..6f530ac 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/testsuite_sqlpp.xml
@@ -4172,6 +4172,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="group-by">
+      <compilation-unit name="listify-3">
+        <output-dir compare="Text">listify-3</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="group-by">
       <compilation-unit name="redundant-var-in-groupby">
         <output-dir compare="Text">redundant-var-in-groupby</output-dir>
       </compilation-unit>
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 a39af41..c33c647 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
@@ -136,8 +136,9 @@
         AbstractLogicalOperator aop = (AbstractLogicalOperator) arg;
         // require the same physical operator, otherwise delivers different data
         // properties
-        if (aop.getOperatorTag() != LogicalOperatorTag.GROUP
-                || aop.getPhysicalOperator().getOperatorTag() != op.getPhysicalOperator().getOperatorTag()) {
+        if (aop.getOperatorTag() != LogicalOperatorTag.GROUP || op.getPhysicalOperator() == null
+                || aop.getPhysicalOperator() == null
+                || op.getPhysicalOperator().getOperatorTag() != aop.getPhysicalOperator().getOperatorTag()) {
             return Boolean.FALSE;
         }
 
@@ -471,7 +472,8 @@
             return Boolean.FALSE;
         }
         // require the same partition property
-        if (!(op.getPhysicalOperator().getOperatorTag() == aop.getPhysicalOperator().getOperatorTag())) {
+        if (op.getPhysicalOperator() == null || aop.getPhysicalOperator() == null
+                || op.getPhysicalOperator().getOperatorTag() != aop.getPhysicalOperator().getOperatorTag()) {
             return Boolean.FALSE;
         }
         variableMapping.clear();
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/subplan/EliminateIsomorphicSubplanRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/subplan/EliminateIsomorphicSubplanRule.java
new file mode 100644
index 0000000..1410a3a
--- /dev/null
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/subplan/EliminateIsomorphicSubplanRule.java
@@ -0,0 +1,165 @@
+/*
+ * 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.subplan;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+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.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.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.SubplanOperator;
+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.rewriter.base.IAlgebraicRewriteRule;
+
+/**
+ * <pre>
+ * This rules searches for
+ *   SUBPLAN_1 { v1 = ... } (directly followed by)
+ *   SUBPLAN_2 { v2 = ... }
+ * and eliminates nested plans from subplan_1 that are isomorphic to nested plans defined by subplan_2.
+ * The variables produced by eliminated nested plans are then ASSIGN-ed to variables produced by
+ * matching nested plans in subplan_2:
+ *   ASSIGN { v1 = v2 }
+ *   SUBPLAN_2 { v2 = ...}
+ *
+ * Note: SUBPLAN_1 will remain in the plan (below ASSIGN) if some of its nested plans could not be eliminated.
+ * </pre>
+ */
+public class EliminateIsomorphicSubplanRule implements IAlgebraicRewriteRule {
+    @Override
+    public boolean rewritePre(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        AbstractLogicalOperator op1 = (AbstractLogicalOperator) opRef.getValue();
+        if (op1.getOperatorTag() != LogicalOperatorTag.SUBPLAN) {
+            return false;
+        }
+        SubplanOperator subplan1 = (SubplanOperator) op1;
+
+        Mutable<ILogicalOperator> op2Ref = subplan1.getInputs().get(0);
+        ILogicalOperator op2 = op2Ref.getValue();
+        if (op2.getOperatorTag() != LogicalOperatorTag.SUBPLAN) {
+            return false;
+        }
+        SubplanOperator subplan2 = (SubplanOperator) op2;
+
+        Map<LogicalVariable, LogicalVariable> assignVarMap = new LinkedHashMap<>();
+        Map<LogicalVariable, LogicalVariable> tmpVarMap = new LinkedHashMap<>();
+        List<LogicalVariable> tmpVarList = new ArrayList<>();
+
+        for (Iterator<ILogicalPlan> nestedPlanIter = subplan1.getNestedPlans().iterator(); nestedPlanIter.hasNext();) {
+            ILogicalPlan nestedPlan = nestedPlanIter.next();
+            for (Iterator<Mutable<ILogicalOperator>> rootOpIter = nestedPlan.getRoots().iterator(); rootOpIter
+                    .hasNext();) {
+                ILogicalOperator rootOp = rootOpIter.next().getValue();
+                if (findIsomorphicPlanRoot(rootOp, subplan2, assignVarMap, tmpVarList, tmpVarMap)) {
+                    rootOpIter.remove();
+                }
+            }
+            if (nestedPlan.getRoots().isEmpty()) {
+                nestedPlanIter.remove();
+            }
+        }
+
+        int assignVarCount = assignVarMap.size();
+        if (assignVarCount == 0) {
+            return false;
+        }
+
+        List<LogicalVariable> assignVars = new ArrayList<>(assignVarCount);
+        List<Mutable<ILogicalExpression>> assignExprs = new ArrayList<>(assignVarCount);
+
+        for (Map.Entry<LogicalVariable, LogicalVariable> me : assignVarMap.entrySet()) {
+            LogicalVariable subplan1Var = me.getKey();
+
+            LogicalVariable subplan2Var = me.getValue();
+            VariableReferenceExpression subplan2VarRef = new VariableReferenceExpression(subplan2Var);
+            subplan2VarRef.setSourceLocation(subplan2.getSourceLocation());
+
+            assignVars.add(subplan1Var);
+            assignExprs.add(new MutableObject<>(subplan2VarRef));
+        }
+
+        Mutable<ILogicalOperator> assignInputOp;
+        if (subplan1.getNestedPlans().isEmpty()) {
+            assignInputOp = op2Ref;
+        } else {
+            // some nested plans were removed from subplan1 -> recompute its type environment
+            context.computeAndSetTypeEnvironmentForOperator(subplan1);
+            assignInputOp = new MutableObject<>(subplan1);
+        }
+
+        AssignOperator assignOp = new AssignOperator(assignVars, assignExprs);
+        assignOp.setSourceLocation(subplan1.getSourceLocation());
+        assignOp.getInputs().add(assignInputOp);
+
+        context.computeAndSetTypeEnvironmentForOperator(assignOp);
+        opRef.setValue(assignOp);
+
+        return true;
+    }
+
+    /**
+     * Finds nested plan root in given subplan that is isomorphic to given operator
+     * and returns their variable mappings
+     */
+    private boolean findIsomorphicPlanRoot(ILogicalOperator op, SubplanOperator subplanOp,
+            Map<LogicalVariable, LogicalVariable> outVarMap, List<LogicalVariable> tmpVarList,
+            Map<LogicalVariable, LogicalVariable> tmpVarMap) throws AlgebricksException {
+        for (ILogicalPlan nestedPlan : subplanOp.getNestedPlans()) {
+            for (Mutable<ILogicalOperator> rootOpRef : nestedPlan.getRoots()) {
+                ILogicalOperator rootOp = rootOpRef.getValue();
+                if (IsomorphismUtilities.isOperatorIsomorphicPlanSegment(op, rootOp)) {
+                    tmpVarList.clear();
+                    VariableUtilities.getProducedVariables(op, tmpVarList);
+                    tmpVarMap.clear();
+                    IsomorphismUtilities.mapVariablesTopDown(rootOp, op, tmpVarMap);
+                    tmpVarMap.keySet().retainAll(tmpVarList);
+                    if (tmpVarMap.size() == tmpVarList.size()) {
+                        outVarMap.putAll(tmpVarMap);
+                        return true;
+                    } else {
+                        return false;
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public boolean rewritePost(Mutable<ILogicalOperator> opRef, IOptimizationContext context)
+            throws AlgebricksException {
+        return false;
+    }
+}