error on unsupported changing of distirbution column in ON CONFLICT for INSERT ... SELECT

src/backend/distributed/planner/insert_select_planner.c

@@ -176,6 +176,14 @@ CreateInsertSelectPlan(Query *originalQuery,
 					   PlannerRestrictionContext *plannerRestrictionContext)
 {
 	DistributedPlan *distributedPlan = NULL;
+	DeferredErrorMessage *deferredError = NULL;
+
+	deferredError = ErrorIfOnConflictNotSupported(originalQuery);
+	if (deferredError != NULL)
+	{
+		/* raising the error as there is no possible solution for the unsupported on conflict statements */
+		RaiseDeferredError(deferredError, ERROR);
+	}
 
 	distributedPlan = CreateDistributedInsertSelectPlan(originalQuery,
 														plannerRestrictionContext);

src/test/regress/expected/multi_insert_select.out

@@ -2735,6 +2735,22 @@ EXECUTE prepared_recursive_insert_select;
 EXECUTE prepared_recursive_insert_select;
 EXECUTE prepared_recursive_insert_select;
 ROLLBACK;
+-- upsert with on conflict update distribution column is unsupported
+INSERT INTO agg_events AS ae
+            (
+                        user_id,
+                        value_1_agg,
+                        agg_time
+            )
+SELECT user_id,
+       value_1,
+       time
+FROM   raw_events_first
+ON conflict (user_id, value_1_agg)
+DO UPDATE
+   SET    user_id = 42
+RETURNING user_id, value_1_agg;
+ERROR:  modifying the partition value of rows is not allowed
 -- wrap in a transaction to improve performance
 BEGIN;
 DROP TABLE coerce_events;

src/test/regress/sql/multi_insert_select.sql

@@ -2104,6 +2104,22 @@ EXECUTE prepared_recursive_insert_select;
 EXECUTE prepared_recursive_insert_select;
 ROLLBACK;
 
+-- upsert with on conflict update distribution column is unsupported
+INSERT INTO agg_events AS ae
+            (
+                        user_id,
+                        value_1_agg,
+                        agg_time
+            )
+SELECT user_id,
+       value_1,
+       time
+FROM   raw_events_first
+ON conflict (user_id, value_1_agg)
+DO UPDATE
+   SET    user_id = 42
+RETURNING user_id, value_1_agg;
+
 -- wrap in a transaction to improve performance
 BEGIN;
 DROP TABLE coerce_events;