diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/queries/query-ASTERIXDB-3512.sqlpp b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/query-ASTERIXDB-3512.sqlpp
new file mode 100644
index 0000000..d51df3b
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/queries/query-ASTERIXDB-3512.sqlpp
@@ -0,0 +1,44 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+
+use test;
+
+create type dt1 as {id: int};
+
+create dataset collection1(dt1) PRIMARY KEY id;
+create dataset collection2(dt1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON collection2 (date: STRING, oid: STRING, sym: STRING, reg: BIGINT);
+
+with tmp1 AS (
+    SELECT S.sym
+    FROM  collection1 AS S
+    WHERE S.date < print_date(current_date(), 'YYYY-MM-DD')),
+  tmp2 AS (
+    SELECT O.sym
+    FROM collection2 AS O
+    WHERE O.date < print_date(current_date(), 'YYYY-MM-DD'))
+SELECT sl1.sym
+FROM tmp1 AS sl1
+UNION ALL
+SELECT sl2.sym
+FROM tmp2 as sl2;
diff --git a/asterixdb/asterix-app/src/test/resources/optimizerts/results/query-ASTERIXDB-3512.plan b/asterixdb/asterix-app/src/test/resources/optimizerts/results/query-ASTERIXDB-3512.plan
new file mode 100644
index 0000000..9160a43
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/optimizerts/results/query-ASTERIXDB-3512.plan
@@ -0,0 +1,28 @@
+-- DISTRIBUTE_RESULT  |PARTITIONED|
+  -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+    -- UNION_ALL  |PARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+        -- STREAM_PROJECT  |PARTITIONED|
+          -- ASSIGN  |PARTITIONED|
+            -- STREAM_SELECT  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                  -- DATASOURCE_SCAN (test.collection1)  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
+      -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+        -- STREAM_PROJECT  |PARTITIONED|
+          -- ASSIGN  |PARTITIONED|
+            -- STREAM_SELECT  |PARTITIONED|
+              -- STREAM_PROJECT  |PARTITIONED|
+                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                  -- BTREE_SEARCH (test.collection2.collection2)  |PARTITIONED|
+                    -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                      -- STABLE_SORT [$$117(ASC)]  |PARTITIONED|
+                        -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                          -- STREAM_PROJECT  |PARTITIONED|
+                            -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                              -- BTREE_SEARCH (test.collection2.idx1)  |PARTITIONED|
+                                -- ONE_TO_ONE_EXCHANGE  |PARTITIONED|
+                                  -- ASSIGN  |PARTITIONED|
+                                    -- EMPTY_TUPLE_SOURCE  |PARTITIONED|
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.1.ddl.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.1.ddl.sqlpp
new file mode 100644
index 0000000..980d4d4
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.1.ddl.sqlpp
@@ -0,0 +1,34 @@
+/*
+ * 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: This test case is to verify the fix for ASTERIXDB-3512
+ */
+
+drop dataverse test if exists;
+create dataverse test;
+
+use test;
+
+create type dt1 as {id: int};
+
+create dataset collection1(dt1) PRIMARY KEY id;
+create dataset collection2(dt1) PRIMARY KEY id;
+
+CREATE INDEX idx1 ON collection2 (date: STRING, oid: STRING, sym: STRING, reg: BIGINT);
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.2.update.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.2.update.sqlpp
new file mode 100644
index 0000000..41879a7
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.2.update.sqlpp
@@ -0,0 +1,38 @@
+/*
+ * 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.
+ */
+
+use test;
+
+upsert into collection1
+[
+    {
+        "id":1,
+        "sym":10,
+        "date": "2024-01-01"
+    }
+];
+
+upsert into collection2
+[
+    {
+        "id":1,
+        "sym":10,
+        "date": "2024-01-01"
+    }
+];
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.query.sqlpp b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.query.sqlpp
new file mode 100644
index 0000000..60f91ad
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/queries_sqlpp/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.query.sqlpp
@@ -0,0 +1,38 @@
+/*
+ * 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: This test case is to verify the fix for ASTERIXDB-3512
+ */
+
+use test;
+
+with tmp1 AS (
+    SELECT S.sym
+    FROM  collection1 AS S
+    WHERE S.date < print_date(current_date(), 'YYYY-MM-DD')),
+  tmp2 AS (
+    SELECT O.sym
+    FROM collection2 AS O
+    WHERE O.date < print_date(current_date(), 'YYYY-MM-DD'))
+SELECT sl1.sym
+FROM tmp1 AS sl1
+UNION ALL
+SELECT sl2.sym
+FROM tmp2 as sl2;
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/results/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.adm b/asterixdb/asterix-app/src/test/resources/runtimets/results/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.adm
new file mode 100644
index 0000000..9ea757d
--- /dev/null
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/results/misc/query-ASTERIXDB-3512/query-ASTERIXDB-3512.3.adm
@@ -0,0 +1,2 @@
+{ "sym": 10 }
+{ "sym": 10 }
\ No newline at end of file
diff --git a/asterixdb/asterix-app/src/test/resources/runtimets/sqlpp_queries.xml b/asterixdb/asterix-app/src/test/resources/runtimets/sqlpp_queries.xml
index 717700f..09b9e23 100644
--- a/asterixdb/asterix-app/src/test/resources/runtimets/sqlpp_queries.xml
+++ b/asterixdb/asterix-app/src/test/resources/runtimets/sqlpp_queries.xml
@@ -7311,6 +7311,11 @@
       </compilation-unit>
     </test-case>
     <test-case FilePath="misc">
+      <compilation-unit name="query-ASTERIXDB-3512">
+        <output-dir compare="Text">query-ASTERIXDB-3512</output-dir>
+      </compilation-unit>
+    </test-case>
+    <test-case FilePath="misc">
       <compilation-unit name="remove_listify">
         <output-dir compare="Text">remove_listify</output-dir>
       </compilation-unit>
diff --git a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
index 956f0b7..84346fd 100644
--- a/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
+++ b/hyracks-fullstack/algebricks/algebricks-rewriter/src/main/java/org/apache/hyracks/algebricks/rewriter/rules/RemoveUnusedAssignAndAggregateRule.java
@@ -42,6 +42,7 @@
 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.EmptyTupleSourceOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.GroupByOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.RunningAggregateOperator;
 import org.apache.hyracks.algebricks.core.algebra.operators.logical.UnionAllOperator;
@@ -163,9 +164,15 @@
             if (!canRemoveOperator(op, opInSubplan, parentOp)) {
                 break;
             }
-            op = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
-            opRef.setValue(op);
-            assignVarsSetForThisOp = removeAssignVarFromConsideration(opRef);
+            if (op.getOperatorTag() == LogicalOperatorTag.AGGREGATE) {
+                op = new EmptyTupleSourceOperator();
+                context.computeAndSetTypeEnvironmentForOperator(op);
+                opRef.setValue(op);
+            } else {
+                op = (AbstractLogicalOperator) op.getInputs().get(0).getValue();
+                opRef.setValue(op);
+                assignVarsSetForThisOp = removeAssignVarFromConsideration(opRef);
+            }
             isTransformed = true;
         }
 
@@ -445,7 +452,7 @@
 
     private static boolean canRemoveOperator(ILogicalOperator op, boolean opInsideSubplan, ILogicalOperator parentOp) {
         LogicalOperatorTag opTag = op.getOperatorTag();
-        if (opTag == LogicalOperatorTag.AGGREGATE || opTag == LogicalOperatorTag.UNIONALL) {
+        if ((opTag == LogicalOperatorTag.AGGREGATE && opInsideSubplan) || opTag == LogicalOperatorTag.UNIONALL) {
             return false;
         }
         if (!opInsideSubplan) {