diff --git a/src/backend/distributed/planner/insert_select_planner.c b/src/backend/distributed/planner/insert_select_planner.c
index cae71845b..06e446783 100644
--- a/src/backend/distributed/planner/insert_select_planner.c
+++ b/src/backend/distributed/planner/insert_select_planner.c
@@ -73,9 +73,9 @@ static List * CreateTargetListForCombineQuery(List *targetList);
 static DeferredErrorMessage * DistributedInsertSelectSupported(Query *queryTree,
 															   RangeTblEntry *insertRte,
 															   RangeTblEntry *subqueryRte,
-															   bool allReferenceTables);
-static DeferredErrorMessage * MultiTaskRouterSelectQuerySupported(Query *query);
-static bool HasUnsupportedDistinctOn(Query *query);
+															   bool allReferenceTables,
+															   PlannerRestrictionContext *
+															   plannerRestrictionContext);
 static DeferredErrorMessage * InsertPartitionColumnMatchesSelect(Query *query,
 																 RangeTblEntry *insertRte,
 																 RangeTblEntry *
@@ -292,7 +292,8 @@ CreateDistributedInsertSelectPlan(Query *originalQuery,
 	distributedPlan->planningError = DistributedInsertSelectSupported(originalQuery,
 																	  insertRte,
 																	  subqueryRte,
-																	  allReferenceTables);
+																	  allReferenceTables,
+																	  plannerRestrictionContext);
 	if (distributedPlan->planningError)
 	{
 		return distributedPlan;
@@ -613,7 +614,8 @@ CreateTargetListForCombineQuery(List *targetList)
  */
 static DeferredErrorMessage *
 DistributedInsertSelectSupported(Query *queryTree, RangeTblEntry *insertRte,
-								 RangeTblEntry *subqueryRte, bool allReferenceTables)
+								 RangeTblEntry *subqueryRte, bool allReferenceTables,
+								 PlannerRestrictionContext *plannerRestrictionContext)
 {
 	Oid selectPartitionColumnTableId = InvalidOid;
 	Oid targetRelationId = insertRte->relid;
@@ -687,8 +689,16 @@ DistributedInsertSelectSupported(Query *queryTree, RangeTblEntry *insertRte,
 							 NULL, NULL);
 	}
 
-	/* we don't support LIMIT, OFFSET and WINDOW functions */
-	DeferredErrorMessage *error = MultiTaskRouterSelectQuerySupported(subquery);
+	/* first apply toplevel pushdown checks to SELECT query */
+	DeferredErrorMessage *error = DeferErrorIfUnsupportedSubqueryPushdown(subquery,
+																		  plannerRestrictionContext);
+	if (error)
+	{
+		return error;
+	}
+
+	/* then apply subquery pushdown checks to SELECT query */
+	error = DeferErrorIfCannotPushdownSubquery(subquery, false);
 	if (error)
 	{
 		return error;
@@ -730,27 +740,6 @@ DistributedInsertSelectSupported(Query *queryTree, RangeTblEntry *insertRte,
 								 "table", NULL, NULL);
 		}
 
-		if (!HasDistributionKey(targetRelationId) ||
-			subqueryRteListProperties->hasSingleShardDistTable)
-		{
-			/*
-			 * XXX: Better to check this regardless of the fact that the target table
-			 *      has a distribution column or not.
-			 */
-			List *distributedRelationIdList = DistributedRelationIdList(subquery);
-			distributedRelationIdList = lappend_oid(distributedRelationIdList,
-													targetRelationId);
-
-			if (!AllDistributedRelationsInListColocated(distributedRelationIdList))
-			{
-				return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-									 "distributed INSERT ... SELECT cannot reference a "
-									 "distributed table without a shard key together "
-									 "with non-colocated distributed tables",
-									 NULL, NULL);
-			}
-		}
-
 		if (HasDistributionKey(targetRelationId))
 		{
 			/* ensure that INSERT's partition column comes from SELECT's partition column */
@@ -760,22 +749,22 @@ DistributedInsertSelectSupported(Query *queryTree, RangeTblEntry *insertRte,
 			{
 				return error;
 			}
-
-			/*
-			 * We expect partition column values come from colocated tables. Note that we
-			 * skip this check from the reference table case given that all reference tables
-			 * are already (and by default) co-located.
-			 */
-			if (!TablesColocated(insertRte->relid, selectPartitionColumnTableId))
-			{
-				return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-									 "INSERT target table and the source relation of the SELECT partition "
-									 "column value must be colocated in distributed INSERT ... SELECT",
-									 NULL, NULL);
-			}
 		}
 	}
 
+	/* All tables in source list and target table should be colocated. */
+	List *distributedRelationIdList = DistributedRelationIdList(subquery);
+	distributedRelationIdList = lappend_oid(distributedRelationIdList,
+											targetRelationId);
+
+	if (!AllDistributedRelationsInListColocated(distributedRelationIdList))
+	{
+		return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
+							 "INSERT target relation and all source relations of the "
+							 "SELECT must be colocated in distributed INSERT ... SELECT",
+							 NULL, NULL);
+	}
+
 	return NULL;
 }
 
@@ -1131,152 +1120,6 @@ ReorderInsertSelectTargetLists(Query *originalQuery, RangeTblEntry *insertRte,
 }
 
 
-/*
- * MultiTaskRouterSelectQuerySupported returns NULL if the query may be used
- * as the source for an INSERT ... SELECT or returns a description why not.
- */
-static DeferredErrorMessage *
-MultiTaskRouterSelectQuerySupported(Query *query)
-{
-	List *queryList = NIL;
-	ListCell *queryCell = NULL;
-	StringInfo errorDetail = NULL;
-	bool hasUnsupportedDistinctOn = false;
-
-	ExtractQueryWalker((Node *) query, &queryList);
-	foreach(queryCell, queryList)
-	{
-		Query *subquery = (Query *) lfirst(queryCell);
-
-		Assert(subquery->commandType == CMD_SELECT);
-
-		/* pushing down rtes without relations yields (shardCount * expectedRows) */
-		if (HasEmptyJoinTree(subquery))
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "Subqueries without relations are not allowed in "
-								 "distributed INSERT ... SELECT queries",
-								 NULL, NULL);
-		}
-
-		/* pushing down limit per shard would yield wrong results */
-		if (subquery->limitCount != NULL)
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "LIMIT clauses are not allowed in distributed INSERT "
-								 "... SELECT queries",
-								 NULL, NULL);
-		}
-
-		/* pushing down limit offest per shard would yield wrong results */
-		if (subquery->limitOffset != NULL)
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "OFFSET clauses are not allowed in distributed "
-								 "INSERT ... SELECT queries",
-								 NULL, NULL);
-		}
-
-		/* group clause list must include partition column */
-		if (subquery->groupClause)
-		{
-			List *groupClauseList = subquery->groupClause;
-			List *targetEntryList = subquery->targetList;
-			List *groupTargetEntryList = GroupTargetEntryList(groupClauseList,
-															  targetEntryList);
-			bool groupOnPartitionColumn = TargetListOnPartitionColumn(subquery,
-																	  groupTargetEntryList);
-			if (!groupOnPartitionColumn)
-			{
-				return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-									 "Group by list without distribution column is "
-									 "not allowed  in distributed INSERT ... "
-									 "SELECT queries",
-									 NULL, NULL);
-			}
-		}
-
-		/*
-		 * We support window functions when the window function
-		 * is partitioned on distribution column.
-		 */
-		if (subquery->windowClause && !SafeToPushdownWindowFunction(subquery,
-																	&errorDetail))
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED, errorDetail->data, NULL,
-								 NULL);
-		}
-
-		if (subquery->setOperations != NULL)
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "Set operations are not allowed in distributed "
-								 "INSERT ... SELECT queries",
-								 NULL, NULL);
-		}
-
-		/*
-		 * We currently do not support grouping sets since it could generate NULL
-		 * results even after the restrictions are applied to the query. A solution
-		 * would be to add the whole query into a subquery and add the restrictions
-		 * on that subquery.
-		 */
-		if (subquery->groupingSets != NULL)
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "grouping sets are not allowed in distributed "
-								 "INSERT ... SELECT queries",
-								 NULL, NULL);
-		}
-
-		/*
-		 * We don't support DISTINCT ON clauses on non-partition columns.
-		 */
-		hasUnsupportedDistinctOn = HasUnsupportedDistinctOn(subquery);
-		if (hasUnsupportedDistinctOn)
-		{
-			return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-								 "DISTINCT ON (non-partition column) clauses are not "
-								 "allowed in distributed INSERT ... SELECT queries",
-								 NULL, NULL);
-		}
-	}
-
-	return NULL;
-}
-
-
-/*
- * HasUnsupportedDistinctOn returns true if the query has distinct on and
- * distinct targets do not contain partition column.
- */
-static bool
-HasUnsupportedDistinctOn(Query *query)
-{
-	ListCell *distinctCell = NULL;
-
-	if (!query->hasDistinctOn)
-	{
-		return false;
-	}
-
-	foreach(distinctCell, query->distinctClause)
-	{
-		SortGroupClause *distinctClause = lfirst(distinctCell);
-		TargetEntry *distinctEntry = get_sortgroupclause_tle(distinctClause,
-															 query->targetList);
-
-		bool skipOuterVars = true;
-		if (IsPartitionColumn(distinctEntry->expr, query, skipOuterVars))
-		{
-			return false;
-		}
-	}
-
-	return true;
-}
-
-
 /*
  * InsertPartitionColumnMatchesSelect returns NULL the partition column in the
  * table targeted by INSERTed matches with the any of the SELECTed table's
diff --git a/src/test/regress/expected/coordinator_shouldhaveshards.out b/src/test/regress/expected/coordinator_shouldhaveshards.out
index 3307e6bb6..46d5bf6a9 100644
--- a/src/test/regress/expected/coordinator_shouldhaveshards.out
+++ b/src/test/regress/expected/coordinator_shouldhaveshards.out
@@ -908,7 +908,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -939,7 +939,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO coordinator_shouldhaveshards.table_2 (key, value) SELECT table_1.key, count(*) AS count FROM coordinator_shouldhaveshards.table_1 WHERE (table_1.key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1.key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/coordinator_shouldhaveshards_0.out b/src/test/regress/expected/coordinator_shouldhaveshards_0.out
index 9b81a6a72..4c9dc0d18 100644
--- a/src/test/regress/expected/coordinator_shouldhaveshards_0.out
+++ b/src/test/regress/expected/coordinator_shouldhaveshards_0.out
@@ -908,7 +908,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -939,7 +939,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO coordinator_shouldhaveshards.table_2 (key, value) SELECT key, count(*) AS count FROM coordinator_shouldhaveshards.table_1 WHERE (key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/insert_select_repartition.out b/src/test/regress/expected/insert_select_repartition.out
index bb77e9d47..b97a82b63 100644
--- a/src/test/regress/expected/insert_select_repartition.out
+++ b/src/test/regress/expected/insert_select_repartition.out
@@ -549,7 +549,7 @@ SELECT create_distributed_table('target_table', 'a');
 INSERT INTO source_table SELECT floor(i/4), i*i FROM generate_series(1, 20) i;
 SET client_min_messages TO DEBUG1;
 INSERT INTO target_table SELECT a, max(b) FROM source_table GROUP BY a;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 RESET client_min_messages;
 SELECT * FROM target_table ORDER BY a;
@@ -622,40 +622,40 @@ INSERT INTO target_table
   WHERE a BETWEEN $1 AND $2 GROUP BY a;
 SET client_min_messages TO DEBUG1;
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 RESET client_min_messages;
 SELECT a, count(*), count(distinct b) distinct_values FROM target_table GROUP BY a ORDER BY a;
@@ -680,25 +680,25 @@ INSERT INTO target_table
   WHERE a=$1 GROUP BY a;
 SET client_min_messages TO DEBUG1;
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT a, count(*), count(distinct b) distinct_values FROM target_table GROUP BY a ORDER BY a;
@@ -761,10 +761,10 @@ WITH r AS (
   INSERT INTO target_table SELECT * FROM source_table RETURNING *
 )
 INSERT INTO target_table SELECT source_table.a, max(source_table.b) FROM source_table NATURAL JOIN r GROUP BY source_table.a;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  only SELECT, UPDATE, or DELETE common table expressions may be router planned
 DEBUG:  generating subplan XXX_1 for CTE r: INSERT INTO insert_select_repartition.target_table (a, b) SELECT source_table.a, source_table.b FROM insert_select_repartition.source_table RETURNING target_table.a, target_table.b
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT a, max AS b FROM (SELECT source_table.a, max(source_table.b) AS max FROM (insert_select_repartition.source_table JOIN (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) r USING (a, b)) GROUP BY source_table.a) citus_insert_select_subquery
 DEBUG:  Router planner cannot handle multi-shard select queries
@@ -1015,7 +1015,7 @@ SELECT create_distributed_table('target_table', 'a');
 INSERT INTO source_table SELECT i, i * i FROM generate_series(1, 10) i;
 SET client_min_messages TO DEBUG2;
 INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2 AS aa FROM source_table;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  performing repartitioned INSERT ... SELECT
 DEBUG:  partitioning SELECT query by column index 0 with name 'a'
@@ -1049,7 +1049,7 @@ EXPLAIN (costs off) INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2
 
 SET client_min_messages TO DEBUG2;
 INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2 AS aa FROM source_table;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
@@ -1104,7 +1104,7 @@ EXPLAIN (costs off) INSERT INTO test(y, x) SELECT a.x, b.y FROM test a JOIN test
 
 SET client_min_messages TO DEBUG1;
 INSERT INTO test(y, x) SELECT a.x, b.y FROM test a JOIN test b USING (y);
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT count(*) FROM test;
@@ -1133,7 +1133,7 @@ EXPLAIN (costs off) INSERT INTO test SELECT a.* FROM test a JOIN test b USING (y
 
 SET client_min_messages TO DEBUG1;
 INSERT INTO test SELECT a.* FROM test a JOIN test b USING (y);
-DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT count(*) FROM test;
@@ -1219,7 +1219,7 @@ ON CONFLICT(c1, c2, c3, c4, c5, c6)
 DO UPDATE SET
  cardinality = enriched.cardinality + excluded.cardinality,
  sum = enriched.sum + excluded.sum;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  performing repartitioned INSERT ... SELECT
 DEBUG:  partitioning SELECT query by column index 0 with name 'c1'
@@ -1302,6 +1302,33 @@ explain (costs off) insert into table_with_user_sequences select y, x from table
                ->  Seq Scan on table_with_user_sequences_4213652 table_with_user_sequences
 (8 rows)
 
+CREATE TABLE dist_table_1(id int);
+SELECT create_distributed_table('dist_table_1','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE TABLE dist_table_2(id int);
+SELECT create_distributed_table('dist_table_2','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with union can be repartitioned. We cannot push down the query
+-- since UNION clause has no FROM clause at top level query.
+SELECT public.coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1(id) SELECT id FROM dist_table_1 UNION SELECT id FROM dist_table_2;
+$$);
+           coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 4
+(4 rows)
+
 -- clean-up
 SET client_min_messages TO WARNING;
 DROP SCHEMA insert_select_repartition CASCADE;
diff --git a/src/test/regress/expected/insert_select_repartition_0.out b/src/test/regress/expected/insert_select_repartition_0.out
index 0aec4f49a..5bcb894cc 100644
--- a/src/test/regress/expected/insert_select_repartition_0.out
+++ b/src/test/regress/expected/insert_select_repartition_0.out
@@ -549,7 +549,7 @@ SELECT create_distributed_table('target_table', 'a');
 INSERT INTO source_table SELECT floor(i/4), i*i FROM generate_series(1, 20) i;
 SET client_min_messages TO DEBUG1;
 INSERT INTO target_table SELECT a, max(b) FROM source_table GROUP BY a;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 RESET client_min_messages;
 SELECT * FROM target_table ORDER BY a;
@@ -622,40 +622,40 @@ INSERT INTO target_table
   WHERE a BETWEEN $1 AND $2 GROUP BY a;
 SET client_min_messages TO DEBUG1;
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(0, 2);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 EXECUTE insert_plan(2, 4);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  performing repartitioned INSERT ... SELECT
 RESET client_min_messages;
 SELECT a, count(*), count(distinct b) distinct_values FROM target_table GROUP BY a ORDER BY a;
@@ -680,25 +680,25 @@ INSERT INTO target_table
   WHERE a=$1 GROUP BY a;
 SET client_min_messages TO DEBUG1;
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_plan(0);
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT a, count(*), count(distinct b) distinct_values FROM target_table GROUP BY a ORDER BY a;
@@ -761,10 +761,10 @@ WITH r AS (
   INSERT INTO target_table SELECT * FROM source_table RETURNING *
 )
 INSERT INTO target_table SELECT source_table.a, max(source_table.b) FROM source_table NATURAL JOIN r GROUP BY source_table.a;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  only SELECT, UPDATE, or DELETE common table expressions may be router planned
 DEBUG:  generating subplan XXX_1 for CTE r: INSERT INTO insert_select_repartition.target_table (a, b) SELECT a, b FROM insert_select_repartition.source_table RETURNING target_table.a, target_table.b
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT a, max AS b FROM (SELECT source_table.a, max(source_table.b) AS max FROM (insert_select_repartition.source_table JOIN (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) r USING (a, b)) GROUP BY source_table.a) citus_insert_select_subquery
 DEBUG:  Router planner cannot handle multi-shard select queries
@@ -1015,7 +1015,7 @@ SELECT create_distributed_table('target_table', 'a');
 INSERT INTO source_table SELECT i, i * i FROM generate_series(1, 10) i;
 SET client_min_messages TO DEBUG2;
 INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2 AS aa FROM source_table;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  performing repartitioned INSERT ... SELECT
 DEBUG:  partitioning SELECT query by column index 0 with name 'a'
@@ -1049,7 +1049,7 @@ EXPLAIN (costs off) INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2
 
 SET client_min_messages TO DEBUG2;
 INSERT INTO target_table SELECT a AS aa, b AS aa, 1 AS aa, 2 AS aa FROM source_table;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
@@ -1104,7 +1104,7 @@ EXPLAIN (costs off) INSERT INTO test(y, x) SELECT a.x, b.y FROM test a JOIN test
 
 SET client_min_messages TO DEBUG1;
 INSERT INTO test(y, x) SELECT a.x, b.y FROM test a JOIN test b USING (y);
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT count(*) FROM test;
@@ -1133,7 +1133,7 @@ EXPLAIN (costs off) INSERT INTO test SELECT a.* FROM test a JOIN test b USING (y
 
 SET client_min_messages TO DEBUG1;
 INSERT INTO test SELECT a.* FROM test a JOIN test b USING (y);
-DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 RESET client_min_messages;
 SELECT count(*) FROM test;
@@ -1219,7 +1219,7 @@ ON CONFLICT(c1, c2, c3, c4, c5, c6)
 DO UPDATE SET
  cardinality = enriched.cardinality + excluded.cardinality,
  sum = enriched.sum + excluded.sum;
-DEBUG:  INSERT target table and the source relation of the SELECT partition column value must be colocated in distributed INSERT ... SELECT
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  performing repartitioned INSERT ... SELECT
 DEBUG:  partitioning SELECT query by column index 0 with name 'c1'
@@ -1302,6 +1302,33 @@ explain (costs off) insert into table_with_user_sequences select y, x from table
                ->  Seq Scan on table_with_user_sequences_4213652 table_with_user_sequences
 (8 rows)
 
+CREATE TABLE dist_table_1(id int);
+SELECT create_distributed_table('dist_table_1','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE TABLE dist_table_2(id int);
+SELECT create_distributed_table('dist_table_2','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with union can be repartitioned. We cannot push down the query
+-- since UNION clause has no FROM clause at top level query.
+SELECT public.coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1(id) SELECT id FROM dist_table_1 UNION SELECT id FROM dist_table_2;
+$$);
+           coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 4
+(4 rows)
+
 -- clean-up
 SET client_min_messages TO WARNING;
 DROP SCHEMA insert_select_repartition CASCADE;
diff --git a/src/test/regress/expected/insert_select_single_shard_table.out b/src/test/regress/expected/insert_select_single_shard_table.out
index 68391abb5..219e7d5d9 100644
--- a/src/test/regress/expected/insert_select_single_shard_table.out
+++ b/src/test/regress/expected/insert_select_single_shard_table.out
@@ -118,73 +118,82 @@ SET client_min_messages TO DEBUG2;
 -- different table types together with single-shard tables.
 -- use a single-shard table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- use a reference table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 JOIN reference_table USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 RIGHT JOIN reference_table USING (b) WHERE reference_table.a >= 1 AND reference_table.a <= 5;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t2.a, nullkey_c1_t2.b FROM nullkey_c1_t2 LEFT JOIN reference_table USING (b);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 INTERSECT SELECT * FROM reference_table;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Intersect and Except are currently unsupported
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- use a colocated single-shard table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 JOIN nullkey_c1_t2 USING (b);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 FULL JOIN nullkey_c1_t2 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 FULL JOIN matview USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot select from a local relation when inserting into a distributed table
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  Local tables cannot be used in distributed queries.
 INSERT INTO distributed_table_c1_t1 SELECT * FROM nullkey_c1_t1 UNION SELECT * FROM nullkey_c1_t2;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- use a non-colocated single-shard table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t2.a, nullkey_c1_t2.b FROM nullkey_c1_t2 LEFT JOIN nullkey_c2_t1 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO distributed_table_c1_t1 SELECT * FROM nullkey_c1_t1 UNION SELECT * FROM nullkey_c2_t1;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a distributed table that is colocated with the target table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO distributed_table_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO distributed_table_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (b);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO distributed_table_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a) WHERE distributed_table_c1_t2.a = 1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a distributed table that is not colocated with the target table
 INSERT INTO distributed_table_c1_t1 SELECT nullkey_c1_t2.a, nullkey_c1_t2.b FROM nullkey_c1_t2 JOIN distributed_table_c2_t1 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a citus local table
@@ -199,12 +208,14 @@ ERROR:  queries that reference a distributed table without a shard key can only
 DETAIL:  Local tables cannot be used in distributed queries.
 -- use append / range distributed tables
 INSERT INTO range_table SELECT * FROM nullkey_c1_t1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO append_table SELECT * FROM nullkey_c1_t1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  INSERT ... SELECT into an append-distributed table is not supported
 SELECT avg(a), avg(b) FROM distributed_table_c1_t1 ORDER BY 1, 2;
@@ -236,11 +247,12 @@ DEBUG:  only reference tables may be queried when targeting a reference table wi
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO reference_table SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 UNION SELECT * FROM reference_table;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Reference tables are not supported with union operator
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO reference_table SELECT nullkey_c1_t2.a, nullkey_c1_t2.b FROM nullkey_c1_t2 LEFT JOIN reference_table USING (b) WHERE b IN (SELECT b FROM matview);
-DEBUG:  only reference tables may be queried when targeting a reference table with distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  Local tables cannot be used in distributed queries.
 -- use a colocated single-shard table
@@ -259,19 +271,19 @@ ERROR:  queries that reference a distributed table without a shard key can only
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a distributed table
 INSERT INTO reference_table SELECT nullkey_c1_t1.a, nullkey_c1_t1.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a);
-DEBUG:  only reference tables may be queried when targeting a reference table with distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO reference_table SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a);
-DEBUG:  only reference tables may be queried when targeting a reference table with distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO reference_table SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (b);
-DEBUG:  only reference tables may be queried when targeting a reference table with distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO reference_table SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM nullkey_c1_t1 JOIN distributed_table_c1_t2 USING (a) WHERE distributed_table_c1_t2.a = 1;
-DEBUG:  only reference tables may be queried when targeting a reference table with distributed INSERT ... SELECT
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a citus local table
@@ -371,20 +383,20 @@ ERROR:  queries that reference a distributed table without a shard key can only
 DETAIL:  Local tables cannot be used in distributed queries.
 -- use a distributed table
 INSERT INTO nullkey_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM distributed_table_c1_t2;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM distributed_table_c1_t2 JOIN reference_table USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT distributed_table_c1_t2.a, distributed_table_c1_t2.b FROM distributed_table_c1_t2 JOIN nullkey_c1_t1 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 -- use a non-colocated single-shard table
 INSERT INTO nullkey_c2_t1 SELECT q.* FROM (SELECT reference_table.* FROM reference_table LEFT JOIN nullkey_c1_t1 USING (a)) q JOIN nullkey_c1_t2 USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- use a materialized view
@@ -392,11 +404,11 @@ INSERT INTO nullkey_c1_t1 SELECT * FROM matview;
 DEBUG:  distributed INSERT ... SELECT can only select from distributed tables
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT reference_table.a, reference_table.b FROM reference_table JOIN matview ON (reference_table.a = matview.a);
-DEBUG:  distributed INSERT ... SELECT cannot select from a local relation when inserting into a distributed table
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT q.* FROM (SELECT reference_table.* FROM reference_table JOIN nullkey_c1_t1 USING (a)) q JOIN matview USING (a);
-DEBUG:  distributed INSERT ... SELECT cannot select from a local relation when inserting into a distributed table
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  Local tables cannot be used in distributed queries.
 -- use append / range distributed tables
@@ -405,7 +417,7 @@ DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT * FROM append_table;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner does not support append-partitioned tables.
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 SELECT avg(a), avg(b) FROM nullkey_c1_t1 ORDER BY 1, 2;
@@ -462,8 +474,7 @@ cte_2 AS (
 )
 INSERT INTO distributed_table_c1_t1
 SELECT cte_1.* FROM cte_1 JOIN cte_2 USING (a) JOIN distributed_table_c1_t2 USING (a) ORDER BY 1,2;
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
-DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  CTE cte_1 is going to be inlined via distributed planning
 DEBUG:  CTE cte_2 is going to be inlined via distributed planning
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
@@ -479,7 +490,8 @@ cte_2 AS (
 )
 INSERT INTO distributed_table_c1_t1
 SELECT * FROM cte_1 UNION SELECT * FROM cte_2 EXCEPT SELECT * FROM reference_table;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  CTEs in subqueries are currently unsupported
 DEBUG:  CTE cte_1 is going to be inlined via distributed planning
 DEBUG:  CTE cte_2 is going to be inlined via distributed planning
 DEBUG:  Creating router plan
@@ -491,7 +503,8 @@ JOIN (
   SELECT b FROM nullkey_c1_t2 ORDER BY b DESC LIMIT 1
 ) t2
 ON t1.b < t2.b;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1 (a, b)
@@ -503,7 +516,9 @@ WITH cte AS (
 )
 SELECT d1, COALESCE(d2, a) FROM cte WHERE d1 IS NOT NULL AND d2 IS NOT NULL;
 DEBUG:  CTE cte is going to be inlined via distributed planning
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  Subquery contains an expression that is not a simple column reference in the same position as the target table's partition column.
+HINT:  Ensure the target table's partition column has a corresponding simple column reference to a distributed table's partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO citus_local_table (a, b)
@@ -523,7 +538,8 @@ LEFT JOIN (
   FROM nullkey_c1_t1
 ) t2 ON t1.b = t2.b
 WHERE t2.rn > 0;
-DEBUG:  Window functions without PARTITION BY on distribution column is currently unsupported
+DEBUG:  cannot push down this subquery
+DETAIL:  Window functions without PARTITION BY on distribution column is currently unsupported
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 (a, b)
@@ -537,7 +553,7 @@ JOIN (
   ) q
 ) t2 ON t1.b = t2.b
 WHERE t2.rn > 2;
-DEBUG:  Window functions without PARTITION BY on distribution column is currently unsupported
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  router planner does not support queries that reference non-colocated distributed tables
 INSERT INTO distributed_table_c1_t1 (a, b)
@@ -551,21 +567,23 @@ JOIN (
   ) q
 ) t2 ON t1.b = t2.b
 WHERE t2.sum_val > 2;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
+-- Temporaryly reduce the verbosity to avoid noise
+-- in the output of the next query.
+SET client_min_messages TO DEBUG1;
 -- MultiTaskRouterSelectQuerySupported() is unnecessarily restrictive
 -- about pushing down queries with DISTINCT ON clause even if the table
 -- doesn't have a shard key. See https://github.com/citusdata/citus/pull/6752.
 INSERT INTO nullkey_c1_t1 SELECT DISTINCT ON (a) a, b FROM nullkey_c1_t2;
-DEBUG:  DISTINCT ON (non-partition column) clauses are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Distributed planning for a fast-path router query
-DEBUG:  Creating router plan
-DEBUG:  Collecting INSERT ... SELECT results on coordinator
+SET client_min_messages TO DEBUG2;
 -- Similarly, we could push down the following query as well. see
 -- https://github.com/citusdata/citus/pull/6831.
 INSERT INTO nullkey_c1_t1 SELECT b, SUM(a) OVER (ORDER BY b) AS sum_val FROM nullkey_c1_t1;
-DEBUG:  Window functions without PARTITION BY on distribution column is currently unsupported
+DEBUG:  cannot push down this subquery
+DETAIL:  Window functions without PARTITION BY on distribution column is currently unsupported
 DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
@@ -576,7 +594,7 @@ JOIN reference_table AS t3 ON (t2.a = t3.a)
 WHERE NOT EXISTS (
   SELECT 1 FROM nullkey_c1_t2 AS t1 WHERE t1.b = t3.b
 );
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table_c1_t1
@@ -585,7 +603,7 @@ FROM nullkey_c1_t1 AS t1
 WHERE t1.a NOT IN (
   SELECT DISTINCT t2.a FROM distributed_table_c1_t2 AS t2
 );
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 ERROR:  queries that reference a distributed table without a shard key can only reference colocated distributed tables or reference tables
 DETAIL:  Router planner cannot handle multi-shard select queries
 INSERT INTO distributed_table_c1_t1
@@ -598,7 +616,8 @@ JOIN (
     SELECT a FROM nullkey_c1_t2
   ) AS t2
 ) AS t3 ON t1.a = t3.a;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- Temporaryly reduce the verbosity to avoid noise
@@ -617,7 +636,7 @@ WHERE t1.a IN (
     ) AS t4 ON t3.a = t4.a
   ) AS t2
 );
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  correlated subqueries are not supported when the FROM clause contains a reference table
 DEBUG:  generating subplan XXX_1 for subquery SELECT a FROM (SELECT t3.a FROM ((SELECT distributed_table_c1_t1.a FROM insert_select_single_shard_table.distributed_table_c1_t1 WHERE (distributed_table_c1_t1.b OPERATOR(pg_catalog.>) 4)) t3 JOIN (SELECT distributed_table_c1_t2.a FROM insert_select_single_shard_table.distributed_table_c1_t2 WHERE (distributed_table_c1_t2.b OPERATOR(pg_catalog.<) 7)) t4 ON ((t3.a OPERATOR(pg_catalog.=) t4.a)))) t2
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT a, b FROM insert_select_single_shard_table.reference_table t1 WHERE (a OPERATOR(pg_catalog.=) ANY (SELECT intermediate_result.a FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(a integer)))
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
@@ -736,16 +755,17 @@ DEBUG:  distributed statement: INSERT INTO insert_select_single_shard_table.null
 SET client_min_messages TO DEBUG1;
 INSERT INTO distributed_table_c1_t1 AS t1 (a, b) SELECT t3.a, t3.b FROM nullkey_c1_t2 t2 JOIN reference_table t3 ON (t2.a = t3.a) ON CONFLICT (a, b)
     DO UPDATE SET b = t1.b + 10;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 AS t1 (a, b) SELECT t3.a, t3.b FROM distributed_table_c1_t1 t2 JOIN reference_table t3 ON (t2.a = t3.a) ON CONFLICT (a)
     DO UPDATE SET a = t1.a + 10;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- This also fails due to https://github.com/citusdata/citus/issues/6826.
 INSERT INTO nullkey_c1_t1 AS t1 (a, b) SELECT t3.a, t3.b FROM distributed_table_c1_t1 t2 JOIN reference_table t3 ON (t2.a = t3.a) WHERE t2.a = 3 ON CONFLICT (a)
     DO UPDATE SET a = (SELECT max(b)+1 FROM distributed_table_c1_t1 WHERE a = 3);
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 ERROR:  cannot execute a distributed query from a query on a shard
 DETAIL:  Executing a distributed query in a function call that may be pushed to a remote node can lead to incorrect results.
diff --git a/src/test/regress/expected/intermediate_result_pruning.out b/src/test/regress/expected/intermediate_result_pruning.out
index f6cf8c1e1..e178765a8 100644
--- a/src/test/regress/expected/intermediate_result_pruning.out
+++ b/src/test/regress/expected/intermediate_result_pruning.out
@@ -762,7 +762,8 @@ ROLLBACK;
 -- We use offset 1 to make sure the result needs to be pulled to the coordinator, offset 0 would be optimized away
 INSERT INTO table_1
 	SELECT * FROM table_2 OFFSET 1;
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- INSERT .. SELECT via coordinator which has intermediate result,
 -- and can be pruned to a single worker because the final query is on
@@ -793,7 +794,7 @@ INSERT INTO table_1
 		SELECT * FROM cte_1
 			UNION
 		SELECT * FROM cte_2);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 1) INTERSECT SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 2)
 DEBUG:  generating subplan XXX_1 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 1)
 DEBUG:  generating subplan XXX_2 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 2)
@@ -830,7 +831,7 @@ INSERT INTO table_1
 	 ) foo
 	 where table_2.key != 1 AND
  	foo.key = table_2.value::int;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 1) INTERSECT SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 2)
 DEBUG:  generating subplan XXX_1 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 1)
 DEBUG:  generating subplan XXX_2 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 2)
@@ -1054,7 +1055,8 @@ inserts AS MATERIALIZED (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM intermediate_result_pruning.table_3
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO intermediate_result_pruning.table_2 (key, value) SELECT table_1.key, count(*) AS count FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.>) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1.key HAVING (count(*) OPERATOR(pg_catalog.<) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/intermediate_result_pruning_0.out b/src/test/regress/expected/intermediate_result_pruning_0.out
index 4ae6b8e16..ec4b489d0 100644
--- a/src/test/regress/expected/intermediate_result_pruning_0.out
+++ b/src/test/regress/expected/intermediate_result_pruning_0.out
@@ -762,7 +762,8 @@ ROLLBACK;
 -- We use offset 1 to make sure the result needs to be pulled to the coordinator, offset 0 would be optimized away
 INSERT INTO table_1
 	SELECT * FROM table_2 OFFSET 1;
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- INSERT .. SELECT via coordinator which has intermediate result,
 -- and can be pruned to a single worker because the final query is on
@@ -793,7 +794,7 @@ INSERT INTO table_1
 		SELECT * FROM cte_1
 			UNION
 		SELECT * FROM cte_2);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 1) INTERSECT SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 2)
 DEBUG:  generating subplan XXX_1 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 1)
 DEBUG:  generating subplan XXX_2 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 2)
@@ -830,7 +831,7 @@ INSERT INTO table_1
 	 ) foo
 	 where table_2.key != 1 AND
  	foo.key = table_2.value::int;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 1) INTERSECT SELECT table_1.key FROM intermediate_result_pruning.table_1 WHERE (table_1.key OPERATOR(pg_catalog.=) 2)
 DEBUG:  generating subplan XXX_1 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 1)
 DEBUG:  generating subplan XXX_2 for subquery SELECT key FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.=) 2)
@@ -1054,7 +1055,8 @@ inserts AS MATERIALIZED (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM intermediate_result_pruning.table_3
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO intermediate_result_pruning.table_2 (key, value) SELECT key, count(*) AS count FROM intermediate_result_pruning.table_1 WHERE (key OPERATOR(pg_catalog.>) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/isolation_select_vs_all.out b/src/test/regress/expected/isolation_select_vs_all.out
index 0485dba78..21be42915 100644
--- a/src/test/regress/expected/isolation_select_vs_all.out
+++ b/src/test/regress/expected/isolation_select_vs_all.out
@@ -341,29 +341,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-router-select s2-insert-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-router-select: SELECT * FROM select_append WHERE id = 1;
-id|data|int_data
----------------------------------------------------------------------
- 1| b  |       1
-(1 row)
-
-step s2-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-router-select s2-update s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
@@ -770,29 +747,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-insert-select s2-router-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s2-router-select: SELECT * FROM select_append WHERE id = 1;
-id|data|int_data
----------------------------------------------------------------------
- 1| b  |       1
-(1 row)
-
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-update s2-router-select s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
@@ -1162,33 +1116,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-real-time-select s2-insert-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-real-time-select: SELECT * FROM select_append ORDER BY 1, 2;
-id|data|int_data
----------------------------------------------------------------------
- 0| a  |       0
- 1| b  |       1
- 2| c  |       2
- 3| d  |       3
- 4| e  |       4
-(5 rows)
-
-step s2-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-real-time-select s2-update s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
@@ -1621,33 +1548,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-insert-select s2-real-time-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s2-real-time-select: SELECT * FROM select_append ORDER BY 1, 2;
-id|data|int_data
----------------------------------------------------------------------
- 0| a  |       0
- 1| b  |       1
- 2| c  |       2
- 3| d  |       3
- 4| e  |       4
-(5 rows)
-
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-update s2-real-time-select s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
@@ -2034,36 +1934,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-adaptive-select s2-insert-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-adaptive-select:
-  SET citus.enable_repartition_joins TO ON;
- SELECT * FROM select_append AS t1 JOIN select_append AS t2 ON t1.id = t2.int_data ORDER BY 1, 2, 3, 4;
-
-id|data|int_data|id|data|int_data
----------------------------------------------------------------------
- 0| a  |       0| 0| a  |       0
- 1| b  |       1| 1| b  |       1
- 2| c  |       2| 2| c  |       2
- 3| d  |       3| 3| d  |       3
- 4| e  |       4| 4| e  |       4
-(5 rows)
-
-step s2-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-adaptive-select s2-update s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
@@ -2538,36 +2408,6 @@ count
 (1 row)
 
 
-starting permutation: s1-initialize s1-begin s1-insert-select s2-adaptive-select s1-commit s1-select-count
-master_create_empty_shard
----------------------------------------------------------------------
-                  6780300
-(1 row)
-
-step s1-initialize: COPY select_append FROM PROGRAM 'echo 0, a, 0 && echo 1, b, 1 && echo 2, c, 2 && echo 3, d, 3 && echo 4, e, 4' WITH (format 'csv', append_to_shard xxxxx);
-step s1-begin: BEGIN;
-step s1-insert-select: INSERT INTO select_append SELECT * FROM select_append;
-step s2-adaptive-select:
-  SET citus.enable_repartition_joins TO ON;
- SELECT * FROM select_append AS t1 JOIN select_append AS t2 ON t1.id = t2.int_data ORDER BY 1, 2, 3, 4;
-
-id|data|int_data|id|data|int_data
----------------------------------------------------------------------
- 0| a  |       0| 0| a  |       0
- 1| b  |       1| 1| b  |       1
- 2| c  |       2| 2| c  |       2
- 3| d  |       3| 3| d  |       3
- 4| e  |       4| 4| e  |       4
-(5 rows)
-
-step s1-commit: COMMIT;
-step s1-select-count: SELECT COUNT(*) FROM select_append;
-count
----------------------------------------------------------------------
-   10
-(1 row)
-
-
 starting permutation: s1-initialize s1-begin s1-update s2-adaptive-select s1-commit s1-select-count
 master_create_empty_shard
 ---------------------------------------------------------------------
diff --git a/src/test/regress/expected/multi_insert_select.out b/src/test/regress/expected/multi_insert_select.out
index ed836d398..abebf314e 100644
--- a/src/test/regress/expected/multi_insert_select.out
+++ b/src/test/regress/expected/multi_insert_select.out
@@ -620,7 +620,8 @@ INSERT INTO agg_events (value_1_agg, user_id)
     DISTINCT ON (value_1) value_1, user_id
   FROM
     raw_events_first;
-DEBUG:  DISTINCT ON (non-partition column) clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Distinct on columns without partition column is currently unsupported
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 SELECT user_id, value_1_agg FROM agg_events ORDER BY 1,2;
@@ -686,7 +687,7 @@ DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT user_id, v1_a
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 ROLLBACK;
--- We don't support CTEs that are referenced in the target list
+-- We do support CTEs that are referenced in the target list
 INSERT INTO agg_events
   WITH sub_cte AS (SELECT 1)
   SELECT
@@ -694,15 +695,11 @@ INSERT INTO agg_events
   FROM
     raw_events_first;
 DEBUG:  CTE sub_cte is going to be inlined via distributed planning
-DEBUG:  Subqueries without relations are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Router planner cannot handle multi-shard select queries
-DEBUG:  performing repartitioned INSERT ... SELECT
-DEBUG:  partitioning SELECT query by column index 0 with name 'user_id'
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id, value_1_agg) SELECT intermediate_result.user_id, intermediate_result.value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300000_to_0}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id, value_1_agg) SELECT intermediate_result.user_id, intermediate_result.value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300001_to_1}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id, value_1_agg) SELECT intermediate_result.user_id, intermediate_result.value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300002_to_2}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id, value_1_agg) SELECT intermediate_result.user_id, intermediate_result.value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300003_to_3}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
--- We support set operations via the coordinator
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id, value_1_agg) SELECT raw_events_first.user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300000 raw_events_first WHERE (raw_events_first.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id, value_1_agg) SELECT raw_events_first.user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300001 raw_events_first WHERE (raw_events_first.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id, value_1_agg) SELECT raw_events_first.user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300002 raw_events_first WHERE (raw_events_first.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id, value_1_agg) SELECT raw_events_first.user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300003 raw_events_first WHERE (raw_events_first.user_id IS NOT NULL)
+-- We support set operations
 BEGIN;
 INSERT INTO
   raw_events_first(user_id)
@@ -711,14 +708,10 @@ SELECT
 FROM
   ((SELECT user_id FROM raw_events_first) UNION
    (SELECT user_id FROM raw_events_second)) as foo;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Router planner cannot handle multi-shard select queries
-DEBUG:  performing repartitioned INSERT ... SELECT
-DEBUG:  partitioning SELECT query by column index 0 with name 'user_id'
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300000 AS citus_table_alias (user_id) SELECT intermediate_result.user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300004_to_0}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300001 AS citus_table_alias (user_id) SELECT intermediate_result.user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300005_to_1}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300002 AS citus_table_alias (user_id) SELECT intermediate_result.user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300006_to_2}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300003 AS citus_table_alias (user_id) SELECT intermediate_result.user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300007_to_3}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300000 AS citus_table_alias (user_id) SELECT foo.user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300000 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300004 raw_events_second) foo WHERE (foo.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300001 AS citus_table_alias (user_id) SELECT foo.user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300001 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300005 raw_events_second) foo WHERE (foo.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300002 AS citus_table_alias (user_id) SELECT foo.user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300002 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300006 raw_events_second) foo WHERE (foo.user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300003 AS citus_table_alias (user_id) SELECT foo.user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300003 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300007 raw_events_second) foo WHERE (foo.user_id IS NOT NULL)
 ROLLBACK;
 -- We do support set operations through recursive planning
 BEGIN;
@@ -727,7 +720,7 @@ INSERT INTO
   raw_events_first(user_id)
   (SELECT user_id FROM raw_events_first) INTERSECT
   (SELECT user_id FROM raw_events_first);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  generating subplan XXX_1 for subquery SELECT user_id FROM multi_insert_select.raw_events_first
@@ -747,7 +740,7 @@ SELECT
 FROM
   ((SELECT user_id FROM raw_events_first WHERE user_id = 15) EXCEPT
    (SELECT user_id FROM raw_events_second where user_id = 17)) as foo;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- some supported LEFT joins
@@ -765,10 +758,16 @@ DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_133000
    raw_events_second.user_id
  FROM
    reference_table LEFT JOIN raw_events_second ON reference_table.user_id = raw_events_second.user_id;
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300004 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300005 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300006 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300007 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
+DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  recursively planning right side of the left join since the outer side is a recurring rel
+DEBUG:  recursively planning distributed relation "raw_events_second" since it is part of a distributed join node that is outer joined with a recurring rel
+DEBUG:  Wrapping relation "raw_events_second" to a subquery
+DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  generating subplan XXX_1 for subquery SELECT user_id FROM multi_insert_select.raw_events_second WHERE true
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table LEFT JOIN (SELECT raw_events_second_1.user_id, NULL::timestamp without time zone AS "time", NULL::integer AS value_1, NULL::integer AS value_2, NULL::double precision AS value_3, NULL::bigint AS value_4 FROM (SELECT intermediate_result.user_id FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer)) raw_events_second_1) raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id)))
+DEBUG:  Creating router plan
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
  INSERT INTO agg_events (user_id)
  SELECT
    raw_events_first.user_id
@@ -1126,7 +1125,8 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
                raw_events_second
         WHERE  raw_events_first.user_id = raw_events_second.user_id
         GROUP  BY raw_events_second.value_3) AS foo;
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Group by list without partition column is currently unsupported when a subquery references a column from another query
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -1281,7 +1281,7 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
         GROUP  BY raw_events_second.value_1
         HAVING SUM(raw_events_second.value_4) > 10) AS foo2 ) as f2
 ON (f.id = f2.id);
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -1327,7 +1327,7 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
         GROUP  BY raw_events_second.value_1
         HAVING SUM(raw_events_second.value_4) > 10) AS foo2 ) as f2
 ON (f.id = f2.id);
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -3242,5 +3242,236 @@ returning text_col_1;
  string
 (1 row)
 
+CREATE TABLE dist_table_3(
+dist_col bigint,
+int_col integer
+);
+SELECT create_distributed_table('dist_table_3', 'dist_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- dist_table_2 and dist_table_3 are non-colocated source tables. Repartitioning is also not possible due to
+-- different types for distribution columns. Citus would not be able to handle this complex insert select.
+INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_3 USING(dist_col);
+ERROR:  complex joins are only supported when all distributed tables are joined on their distribution columns with equal operator
+CREATE TABLE dist_table_4(
+dist_col integer,
+int_col integer
+);
+SELECT create_distributed_table('dist_table_4', 'dist_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- Even if target table distribution column is colocated with dist_table_2's distributed column, source tables dist_table_2 and dist_table_4
+-- are non-colocated. Hence, SELECT part of the query should be pulled to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_4 ON dist_table_2.dist_col = dist_table_4.int_col;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 4
+(4 rows)
+
+-- For INSERT SELECT, when a lateral query references an outer query, push-down is possible even if limit clause exists in the lateral query.
+-- It is because subquery with limit does not need to be merged at coordinator as it is a lateral query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN LATERAL (SELECT * FROM dist_table_2 d2 WHERE d1.dist_col = d2.dist_col LIMIT 3) dummy USING(dist_col);
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- For INSERT SELECT, when push-down is NOT possible when limit clause exists in a subquery at SELECT part of INSERT SELECT.
+-- It is because the subquery with limit needs to be merged at coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN (SELECT * FROM dist_table_2 LIMIT 3) dummy USING(dist_col);
+$$);
+                   coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Limit
+                     ->  Custom Scan (Citus Adaptive)
+                           Task Count: 4
+(7 rows)
+
+CREATE TABLE dist_table_5(id int, id2 int);
+SELECT create_distributed_table('dist_table_5','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE TABLE dist_table_6(id int, id2 int);
+SELECT create_distributed_table('dist_table_6','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with union can be pushed down since UNION clause has FROM clause at top level query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5(id) SELECT id FROM (SELECT id FROM dist_table_5 UNION SELECT id FROM dist_table_6) dummy;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- verify that insert select with sublink can be pushed down when tables are colocated.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = dist_table_6.id) FROM dist_table_6;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+CREATE TABLE ref_table_1(id int);
+SELECT create_reference_table('ref_table_1');
+ create_reference_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with sublink cannot be pushed down when from clause does not contain any distributed relation.
+INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = ref_table_1.id) FROM ref_table_1;
+ERROR:  correlated subqueries are not supported when the FROM clause contains a reference table
+-- verify that insert select cannot be pushed down when we have recurring range table in from clause.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM ref_table_1 WHERE id = 1) FROM ref_table_1;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 1
+(4 rows)
+
+-- verify that insert select cannot be pushed down when we have reference table in outside of outer join.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT a.id FROM dist_table_5 a LEFT JOIN ref_table_1 b ON (true) RIGHT JOIN ref_table_1 c ON (true);
+$$);
+                coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Custom Scan (Citus Adaptive)
+                     Task Count: 4
+(6 rows)
+
+-- verify that insert select cannot be pushed down when it has a recurring outer join in a subquery.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM ref_table_1 LEFT JOIN dist_table_5 USING(id);
+$$);
+                coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Custom Scan (Citus Adaptive)
+                     Task Count: 4
+(6 rows)
+
+CREATE TABLE loc_table_1(id int);
+-- verify that insert select cannot be pushed down when it contains join between local and distributed tables.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM dist_table_5 JOIN loc_table_1 USING(id);
+$$);
+             coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Seq Scan on loc_table_1
+         Task Count: 4
+(6 rows)
+
+CREATE VIEW view_1 AS
+  SELECT id FROM dist_table_6;
+CREATE MATERIALIZED VIEW view_2 AS
+  SELECT id FROM dist_table_6;
+-- verify that insert select cannot be pushed down when it contains view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_1;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- verify that insert select cannot be pushed down when it contains materialized view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_2;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Seq Scan on view_2
+(3 rows)
+
+CREATE TABLE append_table(id integer, data text, int_data int);
+SELECT create_distributed_table('append_table', 'id', 'append');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT master_create_empty_shard('append_table');
+ master_create_empty_shard
+---------------------------------------------------------------------
+                  13300096
+(1 row)
+
+-- verify that insert select push down for append tables are not supported.
+INSERT INTO append_table SELECT * FROM append_table;
+ERROR:  INSERT ... SELECT into an append-distributed table is not supported
+-- verify that CTEs at top level of INSERT SELECT, that can normally be inlined, would not be inlined by INSERT SELECT pushdown planner
+-- and handled by pull to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  INSERT INTO dist_table_5
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 1
+(4 rows)
+
+-- verify that CTEs at top level of SELECT part, would be inlined by Postgres and pushed down by INSERT SELECT planner.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5
+  WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 1
+(2 rows)
+
 SET client_min_messages TO ERROR;
 DROP SCHEMA multi_insert_select CASCADE;
diff --git a/src/test/regress/expected/multi_insert_select_0.out b/src/test/regress/expected/multi_insert_select_0.out
index efc845e88..ee2341759 100644
--- a/src/test/regress/expected/multi_insert_select_0.out
+++ b/src/test/regress/expected/multi_insert_select_0.out
@@ -620,7 +620,8 @@ INSERT INTO agg_events (value_1_agg, user_id)
     DISTINCT ON (value_1) value_1, user_id
   FROM
     raw_events_first;
-DEBUG:  DISTINCT ON (non-partition column) clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Distinct on columns without partition column is currently unsupported
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 SELECT user_id, value_1_agg FROM agg_events ORDER BY 1,2;
@@ -686,7 +687,7 @@ DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT user_id, v1_a
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 ROLLBACK;
--- We don't support CTEs that are referenced in the target list
+-- We do support CTEs that are referenced in the target list
 INSERT INTO agg_events
   WITH sub_cte AS (SELECT 1)
   SELECT
@@ -694,15 +695,11 @@ INSERT INTO agg_events
   FROM
     raw_events_first;
 DEBUG:  CTE sub_cte is going to be inlined via distributed planning
-DEBUG:  Subqueries without relations are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Router planner cannot handle multi-shard select queries
-DEBUG:  performing repartitioned INSERT ... SELECT
-DEBUG:  partitioning SELECT query by column index 0 with name 'user_id'
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300000_to_0}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300001_to_1}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300002_to_2}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, value_1_agg FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300003_to_3}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer, value_1_agg integer)
--- We support set operations via the coordinator
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300000 raw_events_first WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300001 raw_events_first WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300002 raw_events_first WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id, value_1_agg) SELECT user_id, (SELECT sub_cte."?column?" FROM (SELECT 1) sub_cte("?column?")) FROM multi_insert_select.raw_events_first_13300003 raw_events_first WHERE (user_id IS NOT NULL)
+-- We support set operations
 BEGIN;
 INSERT INTO
   raw_events_first(user_id)
@@ -711,14 +708,10 @@ SELECT
 FROM
   ((SELECT user_id FROM raw_events_first) UNION
    (SELECT user_id FROM raw_events_second)) as foo;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Router planner cannot handle multi-shard select queries
-DEBUG:  performing repartitioned INSERT ... SELECT
-DEBUG:  partitioning SELECT query by column index 0 with name 'user_id'
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300000 AS citus_table_alias (user_id) SELECT user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300004_to_0}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300001 AS citus_table_alias (user_id) SELECT user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300005_to_1}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300002 AS citus_table_alias (user_id) SELECT user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300006_to_2}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300003 AS citus_table_alias (user_id) SELECT user_id FROM read_intermediate_results('{repartitioned_results_xxxxx_from_13300007_to_3}'::text[], 'binary'::citus_copy_format) intermediate_result(user_id integer)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300000 AS citus_table_alias (user_id) SELECT user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300000 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300004 raw_events_second) foo WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300001 AS citus_table_alias (user_id) SELECT user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300001 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300005 raw_events_second) foo WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300002 AS citus_table_alias (user_id) SELECT user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300002 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300006 raw_events_second) foo WHERE (user_id IS NOT NULL)
+DEBUG:  distributed statement: INSERT INTO multi_insert_select.raw_events_first_13300003 AS citus_table_alias (user_id) SELECT user_id FROM (SELECT raw_events_first.user_id FROM multi_insert_select.raw_events_first_13300003 raw_events_first UNION SELECT raw_events_second.user_id FROM multi_insert_select.raw_events_second_13300007 raw_events_second) foo WHERE (user_id IS NOT NULL)
 ROLLBACK;
 -- We do support set operations through recursive planning
 BEGIN;
@@ -727,7 +720,7 @@ INSERT INTO
   raw_events_first(user_id)
   (SELECT user_id FROM raw_events_first) INTERSECT
   (SELECT user_id FROM raw_events_first);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  generating subplan XXX_1 for subquery SELECT user_id FROM multi_insert_select.raw_events_first
@@ -747,7 +740,7 @@ SELECT
 FROM
   ((SELECT user_id FROM raw_events_first WHERE user_id = 15) EXCEPT
    (SELECT user_id FROM raw_events_second where user_id = 17)) as foo;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- some supported LEFT joins
@@ -765,10 +758,16 @@ DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_133000
    raw_events_second.user_id
  FROM
    reference_table LEFT JOIN raw_events_second ON reference_table.user_id = raw_events_second.user_id;
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300008 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300004 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300009 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300005 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300010 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300006 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
-DEBUG:  distributed statement: INSERT INTO multi_insert_select.agg_events_13300011 AS citus_table_alias (user_id) SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table_13300012 reference_table LEFT JOIN multi_insert_select.raw_events_second_13300007 raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id))) WHERE (raw_events_second.user_id IS NOT NULL)
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
+DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  recursively planning right side of the left join since the outer side is a recurring rel
+DEBUG:  recursively planning distributed relation "raw_events_second" since it is part of a distributed join node that is outer joined with a recurring rel
+DEBUG:  Wrapping relation "raw_events_second" to a subquery
+DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  generating subplan XXX_1 for subquery SELECT user_id FROM multi_insert_select.raw_events_second WHERE true
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT raw_events_second.user_id FROM (multi_insert_select.reference_table LEFT JOIN (SELECT raw_events_second_1.user_id, NULL::timestamp without time zone AS "time", NULL::integer AS value_1, NULL::integer AS value_2, NULL::double precision AS value_3, NULL::bigint AS value_4 FROM (SELECT intermediate_result.user_id FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer)) raw_events_second_1) raw_events_second ON ((reference_table.user_id OPERATOR(pg_catalog.=) raw_events_second.user_id)))
+DEBUG:  Creating router plan
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
  INSERT INTO agg_events (user_id)
  SELECT
    raw_events_first.user_id
@@ -1126,7 +1125,8 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
                raw_events_second
         WHERE  raw_events_first.user_id = raw_events_second.user_id
         GROUP  BY raw_events_second.value_3) AS foo;
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Group by list without partition column is currently unsupported when a subquery references a column from another query
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -1281,7 +1281,7 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
         GROUP  BY raw_events_second.value_1
         HAVING SUM(raw_events_second.value_4) > 10) AS foo2 ) as f2
 ON (f.id = f2.id);
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -1327,7 +1327,7 @@ FROM   (SELECT SUM(raw_events_second.value_4) AS v4,
         GROUP  BY raw_events_second.value_1
         HAVING SUM(raw_events_second.value_4) > 10) AS foo2 ) as f2
 ON (f.id = f2.id);
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  join prunable for intervals [-2147483648,-1073741825] and [-1073741824,-1]
@@ -3242,5 +3242,236 @@ returning text_col_1;
  string
 (1 row)
 
+CREATE TABLE dist_table_3(
+dist_col bigint,
+int_col integer
+);
+SELECT create_distributed_table('dist_table_3', 'dist_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- dist_table_2 and dist_table_3 are non-colocated source tables. Repartitioning is also not possible due to
+-- different types for distribution columns. Citus would not be able to handle this complex insert select.
+INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_3 USING(dist_col);
+ERROR:  complex joins are only supported when all distributed tables are joined on their distribution columns with equal operator
+CREATE TABLE dist_table_4(
+dist_col integer,
+int_col integer
+);
+SELECT create_distributed_table('dist_table_4', 'dist_col');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- Even if target table distribution column is colocated with dist_table_2's distributed column, source tables dist_table_2 and dist_table_4
+-- are non-colocated. Hence, SELECT part of the query should be pulled to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_4 ON dist_table_2.dist_col = dist_table_4.int_col;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 4
+(4 rows)
+
+-- For INSERT SELECT, when a lateral query references an outer query, push-down is possible even if limit clause exists in the lateral query.
+-- It is because subquery with limit does not need to be merged at coordinator as it is a lateral query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN LATERAL (SELECT * FROM dist_table_2 d2 WHERE d1.dist_col = d2.dist_col LIMIT 3) dummy USING(dist_col);
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- For INSERT SELECT, when push-down is NOT possible when limit clause exists in a subquery at SELECT part of INSERT SELECT.
+-- It is because the subquery with limit needs to be merged at coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN (SELECT * FROM dist_table_2 LIMIT 3) dummy USING(dist_col);
+$$);
+                   coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Limit
+                     ->  Custom Scan (Citus Adaptive)
+                           Task Count: 4
+(7 rows)
+
+CREATE TABLE dist_table_5(id int, id2 int);
+SELECT create_distributed_table('dist_table_5','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE TABLE dist_table_6(id int, id2 int);
+SELECT create_distributed_table('dist_table_6','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with union can be pushed down since UNION clause has FROM clause at top level query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5(id) SELECT id FROM (SELECT id FROM dist_table_5 UNION SELECT id FROM dist_table_6) dummy;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- verify that insert select with sublink can be pushed down when tables are colocated.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = dist_table_6.id) FROM dist_table_6;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+CREATE TABLE ref_table_1(id int);
+SELECT create_reference_table('ref_table_1');
+ create_reference_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with sublink cannot be pushed down when from clause does not contain any distributed relation.
+INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = ref_table_1.id) FROM ref_table_1;
+ERROR:  correlated subqueries are not supported when the FROM clause contains a reference table
+-- verify that insert select cannot be pushed down when we have recurring range table in from clause.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM ref_table_1 WHERE id = 1) FROM ref_table_1;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 1
+(4 rows)
+
+-- verify that insert select cannot be pushed down when we have reference table in outside of outer join.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT a.id FROM dist_table_5 a LEFT JOIN ref_table_1 b ON (true) RIGHT JOIN ref_table_1 c ON (true);
+$$);
+                coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Custom Scan (Citus Adaptive)
+                     Task Count: 4
+(6 rows)
+
+-- verify that insert select cannot be pushed down when it has a recurring outer join in a subquery.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM ref_table_1 LEFT JOIN dist_table_5 USING(id);
+$$);
+                coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Custom Scan (Citus Adaptive)
+                     Task Count: 4
+(6 rows)
+
+CREATE TABLE loc_table_1(id int);
+-- verify that insert select cannot be pushed down when it contains join between local and distributed tables.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM dist_table_5 JOIN loc_table_1 USING(id);
+$$);
+             coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: repartition
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Seq Scan on loc_table_1
+         Task Count: 4
+(6 rows)
+
+CREATE VIEW view_1 AS
+  SELECT id FROM dist_table_6;
+CREATE MATERIALIZED VIEW view_2 AS
+  SELECT id FROM dist_table_6;
+-- verify that insert select cannot be pushed down when it contains view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_1;
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 4
+(2 rows)
+
+-- verify that insert select cannot be pushed down when it contains materialized view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_2;
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Seq Scan on view_2
+(3 rows)
+
+CREATE TABLE append_table(id integer, data text, int_data int);
+SELECT create_distributed_table('append_table', 'id', 'append');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+SELECT master_create_empty_shard('append_table');
+ master_create_empty_shard
+---------------------------------------------------------------------
+                  13300096
+(1 row)
+
+-- verify that insert select push down for append tables are not supported.
+INSERT INTO append_table SELECT * FROM append_table;
+ERROR:  INSERT ... SELECT into an append-distributed table is not supported
+-- verify that CTEs at top level of INSERT SELECT, that can normally be inlined, would not be inlined by INSERT SELECT pushdown planner
+-- and handled by pull to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  INSERT INTO dist_table_5
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+              coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         Task Count: 1
+(4 rows)
+
+-- verify that CTEs at top level of SELECT part, would be inlined by Postgres and pushed down by INSERT SELECT planner.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5
+  WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+       coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus Adaptive)
+   Task Count: 1
+(2 rows)
+
 SET client_min_messages TO ERROR;
 DROP SCHEMA multi_insert_select CASCADE;
diff --git a/src/test/regress/expected/multi_insert_select_conflict.out b/src/test/regress/expected/multi_insert_select_conflict.out
index df7bdc9b9..f344a8b79 100644
--- a/src/test/regress/expected/multi_insert_select_conflict.out
+++ b/src/test/regress/expected/multi_insert_select_conflict.out
@@ -106,7 +106,8 @@ FROM (
 	LIMIT 5
 ) as foo
 ON CONFLICT DO NOTHING;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT col_1, col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2, intermediate_result.col_3 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer, col_3 integer)) foo
@@ -127,7 +128,8 @@ WITH inserted_table AS (
 	ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 RETURNING *
 ) SELECT * FROM inserted_table ORDER BY 1;
 DEBUG:  generating subplan XXX_1 for CTE inserted_table: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT foo.col_1, foo.col_2 FROM (SELECT source_table_1.col_1, source_table_1.col_2, source_table_1.col_3 FROM on_conflict.source_table_1 LIMIT 5) foo ON CONFLICT(col_1) DO UPDATE SET col_2 = excluded.col_2 RETURNING target_table.col_1, target_table.col_2
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT col_1, col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2, intermediate_result.col_3 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer, col_3 integer)) foo
@@ -163,7 +165,8 @@ WITH inserted_table AS (
 	ON CONFLICT(col_1) DO UPDATE SET col_2 = 0 RETURNING *
 ) SELECT * FROM inserted_table ORDER BY 1;
 DEBUG:  generating subplan XXX_1 for CTE inserted_table: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT foo.col_1, foo.col_2 FROM ((SELECT source_table_1.col_1, source_table_1.col_2, source_table_1.col_3 FROM on_conflict.source_table_1 LIMIT 5) UNION (SELECT source_table_2.col_1, source_table_2.col_2, source_table_2.col_3 FROM on_conflict.source_table_2 LIMIT 5)) foo ON CONFLICT(col_1) DO UPDATE SET col_2 = 0 RETURNING target_table.col_1, target_table.col_2
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  push down of limit count: 5
@@ -498,7 +501,8 @@ FROM (
 	LIMIT 5)
 ) as foo
 ON CONFLICT(col_1) DO UPDATE SET col_2 = 0;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  push down of limit count: 5
@@ -560,7 +564,8 @@ DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- intermediate result file
 SET citus.max_adaptive_executor_pool_size TO 1;
 INSERT INTO target_table SELECT * FROM target_table LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 + 1;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 10000
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 SELECT DISTINCT col_2 FROM target_table;
@@ -572,7 +577,8 @@ SELECT DISTINCT col_2 FROM target_table;
 WITH cte_1 AS (INSERT INTO target_table SELECT * FROM target_table LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 + 1 RETURNING *)
 SELECT DISTINCT col_2 FROM cte_1;
 DEBUG:  generating subplan XXX_1 for CTE cte_1: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT target_table_1.col_1, target_table_1.col_2 FROM on_conflict.target_table target_table_1 LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = (excluded.col_2 OPERATOR(pg_catalog.+) 1) RETURNING target_table.col_1, target_table.col_2
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 10000
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT DISTINCT col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer)) cte_1
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
diff --git a/src/test/regress/expected/multi_insert_select_conflict_0.out b/src/test/regress/expected/multi_insert_select_conflict_0.out
index b8f926d30..42b5aed31 100644
--- a/src/test/regress/expected/multi_insert_select_conflict_0.out
+++ b/src/test/regress/expected/multi_insert_select_conflict_0.out
@@ -106,7 +106,8 @@ FROM (
 	LIMIT 5
 ) as foo
 ON CONFLICT DO NOTHING;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT col_1, col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2, intermediate_result.col_3 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer, col_3 integer)) foo
@@ -127,7 +128,8 @@ WITH inserted_table AS (
 	ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 RETURNING *
 ) SELECT * FROM inserted_table ORDER BY 1;
 DEBUG:  generating subplan XXX_1 for CTE inserted_table: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT col_1, col_2 FROM (SELECT source_table_1.col_1, source_table_1.col_2, source_table_1.col_3 FROM on_conflict.source_table_1 LIMIT 5) foo ON CONFLICT(col_1) DO UPDATE SET col_2 = excluded.col_2 RETURNING target_table.col_1, target_table.col_2
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT col_1, col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2, intermediate_result.col_3 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer, col_3 integer)) foo
@@ -163,7 +165,8 @@ WITH inserted_table AS (
 	ON CONFLICT(col_1) DO UPDATE SET col_2 = 0 RETURNING *
 ) SELECT * FROM inserted_table ORDER BY 1;
 DEBUG:  generating subplan XXX_1 for CTE inserted_table: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT col_1, col_2 FROM ((SELECT source_table_1.col_1, source_table_1.col_2, source_table_1.col_3 FROM on_conflict.source_table_1 LIMIT 5) UNION (SELECT source_table_2.col_1, source_table_2.col_2, source_table_2.col_3 FROM on_conflict.source_table_2 LIMIT 5)) foo ON CONFLICT(col_1) DO UPDATE SET col_2 = 0 RETURNING target_table.col_1, target_table.col_2
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  push down of limit count: 5
@@ -498,7 +501,8 @@ FROM (
 	LIMIT 5)
 ) as foo
 ON CONFLICT(col_1) DO UPDATE SET col_2 = 0;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 5
 DEBUG:  generating subplan XXX_1 for subquery SELECT col_1, col_2, col_3 FROM on_conflict.source_table_1 LIMIT 5
 DEBUG:  push down of limit count: 5
@@ -560,7 +564,8 @@ DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- intermediate result file
 SET citus.max_adaptive_executor_pool_size TO 1;
 INSERT INTO target_table SELECT * FROM target_table LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 + 1;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 10000
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 SELECT DISTINCT col_2 FROM target_table;
@@ -572,7 +577,8 @@ SELECT DISTINCT col_2 FROM target_table;
 WITH cte_1 AS (INSERT INTO target_table SELECT * FROM target_table LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = EXCLUDED.col_2 + 1 RETURNING *)
 SELECT DISTINCT col_2 FROM cte_1;
 DEBUG:  generating subplan XXX_1 for CTE cte_1: INSERT INTO on_conflict.target_table (col_1, col_2) SELECT col_1, col_2 FROM on_conflict.target_table LIMIT 10000 ON CONFLICT(col_1) DO UPDATE SET col_2 = (excluded.col_2 OPERATOR(pg_catalog.+) 1) RETURNING target_table.col_1, target_table.col_2
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 10000
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT DISTINCT col_2 FROM (SELECT intermediate_result.col_1, intermediate_result.col_2 FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(col_1 integer, col_2 integer)) cte_1
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
diff --git a/src/test/regress/expected/multi_insert_select_non_pushable_queries.out b/src/test/regress/expected/multi_insert_select_non_pushable_queries.out
index fc3f62385..c4a537277 100644
--- a/src/test/regress/expected/multi_insert_select_non_pushable_queries.out
+++ b/src/test/regress/expected/multi_insert_select_non_pushable_queries.out
@@ -3,6 +3,8 @@
 -- Vanilla funnel query
 ---------------------------------------------------------------------
 ---------------------------------------------------------------------
+CREATE SCHEMA multi_insert_select_non_pushable_queries;
+SET search_path = multi_insert_select_non_pushable_queries,public;
 -- not pushable since the JOIN is not an equi join
 INSERT INTO agg_results_third (user_id, value_1_agg)
 SELECT user_id, array_length(events_table, 1)
@@ -147,7 +149,7 @@ FROM (
   GROUP BY  t1.user_id, hasdone_event
 ) t GROUP BY user_id, hasdone_event
 RETURNING user_id, value_1_agg, value_2_agg;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for subquery SELECT u.user_id, 'step=>1'::text AS event, e."time" FROM public.users_table u, public.events_table e WHERE ((u.user_id OPERATOR(pg_catalog.=) e.user_id) AND (u.user_id OPERATOR(pg_catalog.>=) 10) AND (u.user_id OPERATOR(pg_catalog.<=) 25) AND (e.event_type OPERATOR(pg_catalog.=) ANY (ARRAY[100, 101, 102])))
 DEBUG:  generating subplan XXX_2 for subquery SELECT u.user_id, 'step=>2'::text AS event, e."time" FROM public.users_table u, public.events_table e WHERE ((u.user_id OPERATOR(pg_catalog.=) e.user_id) AND (u.user_id OPERATOR(pg_catalog.>=) 10) AND (u.user_id OPERATOR(pg_catalog.<=) 25) AND (e.event_type OPERATOR(pg_catalog.=) ANY (ARRAY[103, 104, 105])))
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT intermediate_result.user_id, intermediate_result.event, intermediate_result."time" FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, event text, "time" timestamp without time zone) UNION SELECT intermediate_result.user_id, intermediate_result.event, intermediate_result."time" FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, event text, "time" timestamp without time zone)
@@ -305,7 +307,7 @@ GROUP BY
 ORDER BY
   count_pay
 RETURNING user_id, value_1_agg, value_2_agg;
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for subquery SELECT users_table.user_id, 'action=>1'::text AS event, events_table."time" FROM public.users_table, public.events_table WHERE ((users_table.user_id OPERATOR(pg_catalog.=) events_table.user_id) AND (users_table.user_id OPERATOR(pg_catalog.>=) 10) AND (users_table.user_id OPERATOR(pg_catalog.<=) 70) AND (events_table.event_type OPERATOR(pg_catalog.>) 10) AND (events_table.event_type OPERATOR(pg_catalog.<) 12))
 DEBUG:  generating subplan XXX_2 for subquery SELECT users_table.user_id, 'action=>2'::text AS event, events_table."time" FROM public.users_table, public.events_table WHERE ((users_table.user_id OPERATOR(pg_catalog.=) events_table.user_id) AND (users_table.user_id OPERATOR(pg_catalog.>=) 10) AND (users_table.user_id OPERATOR(pg_catalog.<=) 70) AND (events_table.event_type OPERATOR(pg_catalog.>) 12) AND (events_table.event_type OPERATOR(pg_catalog.<) 14))
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT intermediate_result.user_id, intermediate_result.event, intermediate_result."time" FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, event text, "time" timestamp without time zone) UNION SELECT intermediate_result.user_id, intermediate_result.event, intermediate_result."time" FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, event text, "time" timestamp without time zone)
@@ -808,3 +810,36 @@ FROM (
         GROUP BY user_id
 ) AS shard_union
 ORDER BY user_lastseen DESC;
+CREATE TABLE dist_table_1(id int);
+SELECT create_distributed_table('dist_table_1','id');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+CREATE TABLE dist_table_2(id int, id2 int);
+SELECT create_distributed_table('dist_table_2','id2');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+-- verify that insert select with union can be pulled to coordinator. We cannot push down the query
+-- since UNION clause has no FROM clause at top level query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1(id) SELECT id FROM dist_table_1 UNION SELECT id FROM dist_table_2;
+$$);
+                coordinator_plan
+---------------------------------------------------------------------
+ Custom Scan (Citus INSERT ... SELECT)
+   INSERT/SELECT method: pull to coordinator
+   ->  Custom Scan (Citus Adaptive)
+         ->  Distributed Subplan XXX_1
+               ->  Custom Scan (Citus Adaptive)
+                     Task Count: 4
+(6 rows)
+
+DROP SCHEMA multi_insert_select_non_pushable_queries CASCADE;
+NOTICE:  drop cascades to 2 other objects
+DETAIL:  drop cascades to table dist_table_1
+drop cascades to table dist_table_2
diff --git a/src/test/regress/expected/multi_router_planner_fast_path.out b/src/test/regress/expected/multi_router_planner_fast_path.out
index f2f18266b..474d4a107 100644
--- a/src/test/regress/expected/multi_router_planner_fast_path.out
+++ b/src/test/regress/expected/multi_router_planner_fast_path.out
@@ -1876,32 +1876,38 @@ PREPARE insert_sel(int, int) AS
 INSERT INTO articles_hash
 	SELECT * FROM articles_hash WHERE author_id = $2 AND word_count = $1 OFFSET 0;
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 EXECUTE insert_sel(1,1);
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Deferred pruning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
diff --git a/src/test/regress/expected/mx_coordinator_shouldhaveshards.out b/src/test/regress/expected/mx_coordinator_shouldhaveshards.out
index 438e1dcdd..547300460 100644
--- a/src/test/regress/expected/mx_coordinator_shouldhaveshards.out
+++ b/src/test/regress/expected/mx_coordinator_shouldhaveshards.out
@@ -89,7 +89,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -114,7 +114,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2 (key, value) SELECT table_1.key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1 WHERE (table_1.key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1.key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -150,7 +151,7 @@ key
 FROM a JOIN table_2_rep USING (key)
 GROUP BY key
 HAVING (max(table_2_rep.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1_rep ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2_rep USING (key)) GROUP BY a.key HAVING (max(table_2_rep.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -175,7 +176,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1_rep
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2_rep (key, value) SELECT table_1_rep.key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1_rep WHERE (table_1_rep.key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1_rep.key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2_rep.key, table_2_rep.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -215,7 +217,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -240,7 +242,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2 (key, value) SELECT table_1.key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1 WHERE (table_1.key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1.key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -276,7 +279,7 @@ key
 FROM a JOIN table_2_rep USING (key)
 GROUP BY key
 HAVING (max(table_2_rep.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1_rep ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2_rep USING (key)) GROUP BY a.key HAVING (max(table_2_rep.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -301,7 +304,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1_rep
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2_rep (key, value) SELECT table_1_rep.key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1_rep WHERE (table_1_rep.key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY table_1_rep.key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2_rep.key, table_2_rep.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/mx_coordinator_shouldhaveshards_0.out b/src/test/regress/expected/mx_coordinator_shouldhaveshards_0.out
index 398229fbb..15cd69068 100644
--- a/src/test/regress/expected/mx_coordinator_shouldhaveshards_0.out
+++ b/src/test/regress/expected/mx_coordinator_shouldhaveshards_0.out
@@ -89,7 +89,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -114,7 +114,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2 (key, value) SELECT key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1 WHERE (key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -150,7 +151,7 @@ key
 FROM a JOIN table_2_rep USING (key)
 GROUP BY key
 HAVING (max(table_2_rep.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1_rep ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2_rep USING (key)) GROUP BY a.key HAVING (max(table_2_rep.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -175,7 +176,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1_rep
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2_rep (key, value) SELECT key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1_rep WHERE (key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2_rep.key, table_2_rep.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -215,7 +217,7 @@ key
 FROM a JOIN table_2 USING (key)
 GROUP BY key
 HAVING (max(table_2.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1 ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2 USING (key)) GROUP BY a.key HAVING (max(table_2.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -240,7 +242,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2 (key, value) SELECT key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1 WHERE (key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2.key, table_2.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
@@ -276,7 +279,7 @@ key
 FROM a JOIN table_2_rep USING (key)
 GROUP BY key
 HAVING (max(table_2_rep.value) >= (SELECT value FROM a));
-DEBUG:  Group by list without distribution column is not allowed  in distributed INSERT ... SELECT queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  generating subplan XXX_1 for CTE a: SELECT key, value FROM mx_coordinator_shouldhaveshards.table_1_rep ORDER BY key, value DESC LIMIT 1
 DEBUG:  push down of limit count: 1
 DEBUG:  generating subplan XXX_2 for subquery SELECT int4(count(*)) AS auto_coerced_by_citus_0, (a.key)::text AS auto_coerced_by_citus_1 FROM ((SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a JOIN mx_coordinator_shouldhaveshards.table_2_rep USING (key)) GROUP BY a.key HAVING (max(table_2_rep.value) OPERATOR(pg_catalog.>=) (SELECT a_1.value FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) a_1))
@@ -301,7 +304,8 @@ inserts AS (
 ) SELECT count(*) FROM inserts;
 DEBUG:  generating subplan XXX_1 for CTE stats: SELECT count(key) AS m FROM mx_coordinator_shouldhaveshards.table_1_rep
 DEBUG:  generating subplan XXX_2 for CTE inserts: INSERT INTO mx_coordinator_shouldhaveshards.table_2_rep (key, value) SELECT key, count(*) AS count FROM mx_coordinator_shouldhaveshards.table_1_rep WHERE (key OPERATOR(pg_catalog.>=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) GROUP BY key HAVING (count(*) OPERATOR(pg_catalog.<=) (SELECT stats.m FROM (SELECT intermediate_result.m FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(m bigint)) stats)) LIMIT 1 RETURNING table_2_rep.key, table_2_rep.value
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  push down of limit count: 1
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.key, intermediate_result.value FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(key integer, value text)) inserts
 DEBUG:  Subplan XXX_1 will be written to local file
diff --git a/src/test/regress/expected/query_single_shard_table.out b/src/test/regress/expected/query_single_shard_table.out
index 6e1fe1529..ff04ad50e 100644
--- a/src/test/regress/expected/query_single_shard_table.out
+++ b/src/test/regress/expected/query_single_shard_table.out
@@ -827,7 +827,7 @@ INSERT INTO nullkey_c1_t1 SELECT * FROM nullkey_c1_t2;
 SET client_min_messages TO DEBUG2;
 --    between two non-colocated single-shard tables
 INSERT INTO nullkey_c1_t1 SELECT * FROM nullkey_c2_t1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
@@ -848,7 +848,7 @@ INSERT INTO nullkey_c1_t1 SELECT * FROM reference_table;
 
 SET client_min_messages TO DEBUG2;
 INSERT INTO nullkey_c1_t1 SELECT * FROM distributed_table;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  INSERT target relation and all source relations of the SELECT must be colocated in distributed INSERT ... SELECT
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO nullkey_c1_t1 SELECT * FROM citus_local_table;
@@ -865,7 +865,8 @@ DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO distributed_table SELECT * FROM nullkey_c1_t1;
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
+DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
 DEBUG:  Distributed planning for a fast-path router query
 DEBUG:  Creating router plan
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
@@ -1197,6 +1198,8 @@ SELECT COALESCE(raw_events_first.user_id, users_ref_table.user_id)
 FROM raw_events_first
      RIGHT JOIN (users_ref_table LEFT JOIN raw_events_second ON users_ref_table.user_id = raw_events_second.user_id)
      ON raw_events_first.user_id = users_ref_table.user_id;
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- using a full join
 INSERT INTO agg_events (user_id, value_1_agg)
 SELECT t1.user_id AS col1,
@@ -1227,6 +1230,8 @@ FROM   users_ref_table
 WHERE  NOT EXISTS (SELECT 1
                    FROM   raw_events_second
                    WHERE  raw_events_second.user_id = users_ref_table.user_id);
+DEBUG:  correlated subqueries are not supported when the FROM clause contains a reference table
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- using inner join
 INSERT INTO agg_events (user_id)
 SELECT raw_events_first.user_id
@@ -1247,13 +1252,16 @@ WHERE raw_events_first.value_1 IN (10, 11,12) OR users_ref_table.user_id IN (1,2
 -- Below "limit / offset clause" test and some others are examples of this.
 -- limit / offset clause
 INSERT INTO agg_events (user_id) SELECT raw_events_first.user_id FROM raw_events_first LIMIT 1;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO agg_events (user_id) SELECT raw_events_first.user_id FROM raw_events_first OFFSET 1;
-DEBUG:  OFFSET clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Offset clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO agg_events (user_id) SELECT users_ref_table.user_id FROM users_ref_table LIMIT 1;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- using a materialized cte
 WITH cte AS MATERIALIZED
@@ -1265,9 +1273,15 @@ DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO raw_events_second
   WITH cte AS MATERIALIZED (SELECT * FROM raw_events_first)
   SELECT user_id * 1000, time, value_1, value_2, value_3, value_4 FROM cte;
+DEBUG:  cannot push down this subquery
+DETAIL:  CTEs in subqueries are currently unsupported
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO raw_events_second (user_id)
   WITH cte AS MATERIALIZED (SELECT * FROM users_ref_table)
   SELECT user_id FROM cte;
+DEBUG:  cannot push down this subquery
+DETAIL:  CTEs in subqueries are currently unsupported
+DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- using a regular cte
 WITH cte AS (SELECT * FROM raw_events_first)
 INSERT INTO raw_events_second
@@ -1286,8 +1300,6 @@ INSERT INTO agg_events
   FROM
     raw_events_first;
 DEBUG:  CTE sub_cte is going to be inlined via distributed planning
-DEBUG:  Subqueries without relations are not allowed in distributed INSERT ... SELECT queries
-DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- we still support complex joins via INSERT's cte list ..
 WITH cte AS (
     SELECT DISTINCT(reference_table.a) AS a, 1 AS b
@@ -1311,7 +1323,7 @@ WITH cte AS (
 )
   SELECT (a+5)*2, b FROM cte;
 DEBUG:  CTE cte is going to be inlined via distributed planning
-DEBUG:  distributed INSERT ... SELECT cannot reference a distributed table without a shard key together with non-colocated distributed tables
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
 DEBUG:  recursively planning left side of the right join since the outer side is a recurring rel
 DEBUG:  recursively planning distributed relation "distributed_table" since it is part of a distributed join node that is outer joined with a recurring rel
 DEBUG:  Wrapping relation "distributed_table" to a subquery
@@ -1323,13 +1335,15 @@ INSERT INTO
   raw_events_first(user_id)
   (SELECT user_id FROM raw_events_first) INTERSECT
   (SELECT user_id FROM raw_events_first);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Intersect and Except are currently unsupported
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 INSERT INTO
   raw_events_first(user_id)
   (SELECT user_id FROM users_ref_table) INTERSECT
   (SELECT user_id FROM raw_events_first);
-DEBUG:  Set operations are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Intersect and Except are currently unsupported
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
 -- group by clause inside subquery
 INSERT INTO agg_events
diff --git a/src/test/regress/expected/recurring_outer_join.out b/src/test/regress/expected/recurring_outer_join.out
index 3cd7cc6dc..aa8cb906d 100644
--- a/src/test/regress/expected/recurring_outer_join.out
+++ b/src/test/regress/expected/recurring_outer_join.out
@@ -1969,8 +1969,7 @@ BEGIN;
   FROM ref_1 t1
   LEFT JOIN dist_1 t2
   ON (t1.a = t2.a);
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
-DETAIL:  The target table's partition column should correspond to a partition column in the subquery.
+DEBUG:  cannot perform a lateral outer join when a distributed subquery references a reference table
 DEBUG:  recursively planning right side of the left join since the outer side is a recurring rel
 DEBUG:  recursively planning distributed relation "dist_1" "t2" since it is part of a distributed join node that is outer joined with a recurring rel
 DEBUG:  Wrapping relation "dist_1" "t2" to a subquery
@@ -1986,9 +1985,7 @@ BEGIN;
   JOIN
   (ref_1 t2 LEFT JOIN dist_1 t3 USING(a)) t4
   ON (t1.a = t4.a);
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
-DETAIL:  Subquery contains an operator in the same position as the target table's partition column.
-HINT:  Ensure the target table's partition column has a corresponding simple column reference to a distributed table's partition column in the subquery.
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  recursively planning right side of the left join since the outer side is a recurring rel
 DEBUG:  recursively planning distributed relation "dist_1" "t3" since it is part of a distributed join node that is outer joined with a recurring rel
 DEBUG:  Wrapping relation "dist_1" "t3" to a subquery
@@ -2005,7 +2002,7 @@ BEGIN;
   JOIN
   (ref_1 t2 LEFT JOIN dist_1 t3 USING(a)) t4
   ON (t1.a = t4.a);
-DEBUG:  Router planner cannot handle multi-shard select queries
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  recursively planning right side of the left join since the outer side is a recurring rel
 DEBUG:  recursively planning distributed relation "dist_1" "t3" since it is part of a distributed join node that is outer joined with a recurring rel
 DEBUG:  Wrapping relation "dist_1" "t3" to a subquery
diff --git a/src/test/regress/expected/with_dml.out b/src/test/regress/expected/with_dml.out
index b5141db33..f2743a8d9 100644
--- a/src/test/regress/expected/with_dml.out
+++ b/src/test/regress/expected/with_dml.out
@@ -103,9 +103,7 @@ WITH ids_to_insert AS
 INSERT INTO distributed_table
        SELECT DISTINCT ids_to_insert.tenant_id FROM ids_to_insert, distributed_table
        		WHERE  distributed_table.tenant_id < ids_to_insert.tenant_id;
-DEBUG:  cannot perform distributed INSERT INTO ... SELECT because the partition columns in the source table and subquery do not match
-DETAIL:  Subquery contains an expression that is not a simple column reference in the same position as the target table's partition column.
-HINT:  Ensure the target table's partition column has a corresponding simple column reference to a distributed table's partition column in the subquery.
+DEBUG:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
 DEBUG:  CTE ids_to_insert is going to be inlined via distributed planning
 DEBUG:  generating subplan XXX_1 for subquery SELECT (((tenant_id)::integer OPERATOR(pg_catalog.*) 100))::text AS tenant_id FROM with_dml.distributed_table WHERE (dept OPERATOR(pg_catalog.>) 7)
 DEBUG:  generating subplan XXX_2 for subquery SELECT DISTINCT ids_to_insert.tenant_id FROM (SELECT intermediate_result.tenant_id FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(tenant_id text)) ids_to_insert, with_dml.distributed_table WHERE (distributed_table.tenant_id OPERATOR(pg_catalog.<) ids_to_insert.tenant_id)
diff --git a/src/test/regress/expected/with_modifying.out b/src/test/regress/expected/with_modifying.out
index 9f62271d5..997c62f93 100644
--- a/src/test/regress/expected/with_modifying.out
+++ b/src/test/regress/expected/with_modifying.out
@@ -956,7 +956,8 @@ WITH first_query AS (INSERT INTO modify_table (id) VALUES (10001)),
 SET client_min_messages TO debug2;
 -- pushed down without the insert
 WITH mb AS (UPDATE modify_table SET val = 3 WHERE id = 3 RETURNING NULL) INSERT INTO modify_table WITH ma AS (SELECT * FROM modify_table LIMIT 10) SELECT count(*) FROM mb;
-DEBUG:  LIMIT clauses are not allowed in distributed INSERT ... SELECT queries
+DEBUG:  cannot push down this subquery
+DETAIL:  Limit clause is currently unsupported when a subquery references a column from another query
 DEBUG:  Creating router plan
 DEBUG:  query has a single distribution column value: 3
 DEBUG:  Collecting INSERT ... SELECT results on coordinator
diff --git a/src/test/regress/multi_1_schedule b/src/test/regress/multi_1_schedule
index b5943f899..0936a9625 100644
--- a/src/test/regress/multi_1_schedule
+++ b/src/test/regress/multi_1_schedule
@@ -65,7 +65,12 @@ test: multi_remove_node_reference_table
 test: multi_create_table
 test: multi_create_table_superuser
 test: multi_master_protocol multi_load_data multi_load_data_superuser multi_behavioral_analytics_create_table
-test: multi_behavioral_analytics_basics multi_behavioral_analytics_single_shard_queries multi_insert_select_non_pushable_queries multi_insert_select multi_behavioral_analytics_create_table_superuser
+test: multi_behavioral_analytics_basics multi_behavioral_analytics_single_shard_queries multi_behavioral_analytics_create_table_superuser
+
+# We don't parallelize the following test with the ones above because they're
+# not idempotent and hence causing flaky test detection check to fail.
+test: multi_insert_select_non_pushable_queries multi_insert_select
+
 test: multi_shard_update_delete recursive_dml_with_different_planners_executors
 test: insert_select_repartition window_functions dml_recursive multi_insert_select_window
 test: multi_insert_select_conflict citus_table_triggers alter_table_single_shard_table
diff --git a/src/test/regress/multi_schedule b/src/test/regress/multi_schedule
index a78ee6088..6dcf41266 100644
--- a/src/test/regress/multi_schedule
+++ b/src/test/regress/multi_schedule
@@ -12,7 +12,12 @@ test: replicated_table_disable_node
 test: multi_create_table
 test: multi_create_table_superuser
 test: multi_create_table_constraints multi_master_protocol multi_load_data multi_load_data_superuser multi_behavioral_analytics_create_table
-test: multi_behavioral_analytics_basics multi_behavioral_analytics_single_shard_queries multi_insert_select_non_pushable_queries multi_insert_select multi_behavioral_analytics_create_table_superuser
+test: multi_behavioral_analytics_basics multi_behavioral_analytics_single_shard_queries multi_behavioral_analytics_create_table_superuser
+
+# We don't parallelize the following test with the ones above because they're
+# not idempotent and hence causing flaky test detection check to fail.
+test: multi_insert_select_non_pushable_queries multi_insert_select
+
 test: multi_shard_update_delete recursive_dml_with_different_planners_executors
 test: insert_select_repartition window_functions dml_recursive multi_insert_select_window
 test: multi_insert_select_conflict citus_table_triggers
diff --git a/src/test/regress/spec/isolation_select_vs_all.spec b/src/test/regress/spec/isolation_select_vs_all.spec
index a3b65ca77..3611e627e 100644
--- a/src/test/regress/spec/isolation_select_vs_all.spec
+++ b/src/test/regress/spec/isolation_select_vs_all.spec
@@ -35,7 +35,6 @@ step "s1-adaptive-select"
 	SELECT * FROM select_append AS t1 JOIN select_append AS t2 ON t1.id = t2.int_data ORDER BY 1, 2, 3, 4;
 }
 step "s1-insert" { INSERT INTO select_append VALUES(0, 'k', 0); }
-step "s1-insert-select" { INSERT INTO select_append SELECT * FROM select_append; }
 step "s1-update" { UPDATE select_append SET data = 'l' WHERE id = 0; }
 step "s1-delete" { DELETE FROM select_append WHERE id = 1; }
 step "s1-truncate" { TRUNCATE select_append; }
@@ -65,7 +64,6 @@ step "s2-adaptive-select"
 	SELECT * FROM select_append AS t1 JOIN select_append AS t2 ON t1.id = t2.int_data ORDER BY 1, 2, 3, 4;
 }
 step "s2-insert" { INSERT INTO select_append VALUES(0, 'k', 0); }
-step "s2-insert-select" { INSERT INTO select_append SELECT * FROM select_append; }
 step "s2-update" { UPDATE select_append SET data = 'l' WHERE id = 0; }
 step "s2-delete" { DELETE FROM select_append WHERE id = 1; }
 step "s2-truncate" { TRUNCATE select_append; }
@@ -101,7 +99,6 @@ permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-adaptive-select"
 
 // permutations - router SELECT first
 permutation "s1-initialize" "s1-begin" "s1-router-select" "s2-insert" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-router-select" "s2-insert-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-router-select" "s2-update" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-router-select" "s2-delete" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-router-select" "s2-truncate" "s1-commit" "s1-select-count"
@@ -119,7 +116,6 @@ permutation "s1-drop" "s1-create-non-distributed-table" "s1-begin" "s1-router-se
 
 // permutations - router SELECT second
 permutation "s1-initialize" "s1-begin" "s1-insert" "s2-router-select" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-insert-select" "s2-router-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-update" "s2-router-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-delete" "s2-router-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-truncate" "s2-router-select" "s1-commit" "s1-select-count"
@@ -136,7 +132,6 @@ permutation "s1-drop" "s1-create-non-distributed-table" "s1-begin" "s1-distribut
 
 // permutations - real-time SELECT first
 permutation "s1-initialize" "s1-begin" "s1-real-time-select" "s2-insert" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-real-time-select" "s2-insert-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-real-time-select" "s2-update" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-real-time-select" "s2-delete" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-real-time-select" "s2-truncate" "s1-commit" "s1-select-count"
@@ -153,7 +148,6 @@ permutation "s1-drop" "s1-create-non-distributed-table" "s1-begin" "s1-real-time
 
 // permutations - real-time SELECT second
 permutation "s1-initialize" "s1-begin" "s1-insert" "s2-real-time-select" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-insert-select" "s2-real-time-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-update" "s2-real-time-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-delete" "s2-real-time-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-truncate" "s2-real-time-select" "s1-commit" "s1-select-count"
@@ -169,7 +163,6 @@ permutation "s1-drop" "s1-create-non-distributed-table" "s1-begin" "s1-distribut
 
 // permutations - adaptive SELECT first
 permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-insert" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-insert-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-update" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-delete" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-adaptive-select" "s2-truncate" "s1-commit" "s1-select-count"
@@ -186,7 +179,6 @@ permutation "s1-drop" "s1-create-non-distributed-table" "s1-begin" "s1-adaptive-
 
 // permutations - adaptive SELECT second
 permutation "s1-initialize" "s1-begin" "s1-insert" "s2-adaptive-select" "s1-commit" "s1-select-count"
-permutation "s1-initialize" "s1-begin" "s1-insert-select" "s2-adaptive-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-update" "s2-adaptive-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-delete" "s2-adaptive-select" "s1-commit" "s1-select-count"
 permutation "s1-initialize" "s1-begin" "s1-truncate" "s2-adaptive-select" "s1-commit" "s1-select-count"
diff --git a/src/test/regress/sql/insert_select_repartition.sql b/src/test/regress/sql/insert_select_repartition.sql
index 526b6eff5..4d13a83f4 100644
--- a/src/test/regress/sql/insert_select_repartition.sql
+++ b/src/test/regress/sql/insert_select_repartition.sql
@@ -647,6 +647,17 @@ insert into table_with_user_sequences values (1,1);
 select create_distributed_table('table_with_user_sequences','x');
 explain (costs off) insert into table_with_user_sequences select y, x from table_with_user_sequences;
 
+CREATE TABLE dist_table_1(id int);
+SELECT create_distributed_table('dist_table_1','id');
+CREATE TABLE dist_table_2(id int);
+SELECT create_distributed_table('dist_table_2','id');
+
+-- verify that insert select with union can be repartitioned. We cannot push down the query
+-- since UNION clause has no FROM clause at top level query.
+SELECT public.coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1(id) SELECT id FROM dist_table_1 UNION SELECT id FROM dist_table_2;
+$$);
+
 -- clean-up
 SET client_min_messages TO WARNING;
 DROP SCHEMA insert_select_repartition CASCADE;
diff --git a/src/test/regress/sql/insert_select_single_shard_table.sql b/src/test/regress/sql/insert_select_single_shard_table.sql
index f428752ec..6593ab90b 100644
--- a/src/test/regress/sql/insert_select_single_shard_table.sql
+++ b/src/test/regress/sql/insert_select_single_shard_table.sql
@@ -325,11 +325,17 @@ JOIN (
 ) t2 ON t1.b = t2.b
 WHERE t2.sum_val > 2;
 
+-- Temporaryly reduce the verbosity to avoid noise
+-- in the output of the next query.
+SET client_min_messages TO DEBUG1;
+
 -- MultiTaskRouterSelectQuerySupported() is unnecessarily restrictive
 -- about pushing down queries with DISTINCT ON clause even if the table
 -- doesn't have a shard key. See https://github.com/citusdata/citus/pull/6752.
 INSERT INTO nullkey_c1_t1 SELECT DISTINCT ON (a) a, b FROM nullkey_c1_t2;
 
+SET client_min_messages TO DEBUG2;
+
 -- Similarly, we could push down the following query as well. see
 -- https://github.com/citusdata/citus/pull/6831.
 INSERT INTO nullkey_c1_t1 SELECT b, SUM(a) OVER (ORDER BY b) AS sum_val FROM nullkey_c1_t1;
diff --git a/src/test/regress/sql/multi_insert_select.sql b/src/test/regress/sql/multi_insert_select.sql
index b14affddf..4d202041f 100644
--- a/src/test/regress/sql/multi_insert_select.sql
+++ b/src/test/regress/sql/multi_insert_select.sql
@@ -536,7 +536,7 @@ INSERT INTO agg_events
               fist_table_agg;
 ROLLBACK;
 
--- We don't support CTEs that are referenced in the target list
+-- We do support CTEs that are referenced in the target list
 INSERT INTO agg_events
   WITH sub_cte AS (SELECT 1)
   SELECT
@@ -544,7 +544,7 @@ INSERT INTO agg_events
   FROM
     raw_events_first;
 
--- We support set operations via the coordinator
+-- We support set operations
 BEGIN;
 
 INSERT INTO
@@ -2341,5 +2341,121 @@ join dist_table_2 t2 using (dist_col)
 limit 1
 returning text_col_1;
 
+CREATE TABLE dist_table_3(
+dist_col bigint,
+int_col integer
+);
+
+SELECT create_distributed_table('dist_table_3', 'dist_col');
+
+-- dist_table_2 and dist_table_3 are non-colocated source tables. Repartitioning is also not possible due to
+-- different types for distribution columns. Citus would not be able to handle this complex insert select.
+INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_3 USING(dist_col);
+
+CREATE TABLE dist_table_4(
+dist_col integer,
+int_col integer
+);
+SELECT create_distributed_table('dist_table_4', 'dist_col');
+
+-- Even if target table distribution column is colocated with dist_table_2's distributed column, source tables dist_table_2 and dist_table_4
+-- are non-colocated. Hence, SELECT part of the query should be pulled to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT dist_table_2.dist_col FROM dist_table_2 JOIN dist_table_4 ON dist_table_2.dist_col = dist_table_4.int_col;
+$$);
+
+-- For INSERT SELECT, when a lateral query references an outer query, push-down is possible even if limit clause exists in the lateral query.
+-- It is because subquery with limit does not need to be merged at coordinator as it is a lateral query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN LATERAL (SELECT * FROM dist_table_2 d2 WHERE d1.dist_col = d2.dist_col LIMIT 3) dummy USING(dist_col);
+$$);
+
+-- For INSERT SELECT, when push-down is NOT possible when limit clause exists in a subquery at SELECT part of INSERT SELECT.
+-- It is because the subquery with limit needs to be merged at coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1 SELECT d1.dist_col FROM dist_table_1 d1 LEFT JOIN (SELECT * FROM dist_table_2 LIMIT 3) dummy USING(dist_col);
+$$);
+
+CREATE TABLE dist_table_5(id int, id2 int);
+SELECT create_distributed_table('dist_table_5','id');
+CREATE TABLE dist_table_6(id int, id2 int);
+SELECT create_distributed_table('dist_table_6','id');
+
+-- verify that insert select with union can be pushed down since UNION clause has FROM clause at top level query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5(id) SELECT id FROM (SELECT id FROM dist_table_5 UNION SELECT id FROM dist_table_6) dummy;
+$$);
+
+-- verify that insert select with sublink can be pushed down when tables are colocated.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = dist_table_6.id) FROM dist_table_6;
+$$);
+
+CREATE TABLE ref_table_1(id int);
+SELECT create_reference_table('ref_table_1');
+
+-- verify that insert select with sublink cannot be pushed down when from clause does not contain any distributed relation.
+INSERT INTO dist_table_5 SELECT id, (SELECT id FROM dist_table_5 WHERE dist_table_5.id = ref_table_1.id) FROM ref_table_1;
+
+-- verify that insert select cannot be pushed down when we have recurring range table in from clause.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id, (SELECT id FROM ref_table_1 WHERE id = 1) FROM ref_table_1;
+$$);
+
+-- verify that insert select cannot be pushed down when we have reference table in outside of outer join.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT a.id FROM dist_table_5 a LEFT JOIN ref_table_1 b ON (true) RIGHT JOIN ref_table_1 c ON (true);
+$$);
+
+-- verify that insert select cannot be pushed down when it has a recurring outer join in a subquery.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM ref_table_1 LEFT JOIN dist_table_5 USING(id);
+$$);
+
+CREATE TABLE loc_table_1(id int);
+
+-- verify that insert select cannot be pushed down when it contains join between local and distributed tables.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT id FROM dist_table_5 JOIN loc_table_1 USING(id);
+$$);
+
+CREATE VIEW view_1 AS
+  SELECT id FROM dist_table_6;
+
+CREATE MATERIALIZED VIEW view_2 AS
+  SELECT id FROM dist_table_6;
+
+-- verify that insert select cannot be pushed down when it contains view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_1;
+$$);
+
+-- verify that insert select cannot be pushed down when it contains materialized view.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5 SELECT * FROM view_2;
+$$);
+
+CREATE TABLE append_table(id integer, data text, int_data int);
+SELECT create_distributed_table('append_table', 'id', 'append');
+SELECT master_create_empty_shard('append_table');
+
+-- verify that insert select push down for append tables are not supported.
+INSERT INTO append_table SELECT * FROM append_table;
+
+-- verify that CTEs at top level of INSERT SELECT, that can normally be inlined, would not be inlined by INSERT SELECT pushdown planner
+-- and handled by pull to coordinator.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  INSERT INTO dist_table_5
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+
+-- verify that CTEs at top level of SELECT part, would be inlined by Postgres and pushed down by INSERT SELECT planner.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_5
+  WITH cte_1 AS (SELECT id FROM dist_table_5 WHERE id = 5)
+  SELECT id FROM dist_table_5 JOIN cte_1 USING(id);
+$$);
+
 SET client_min_messages TO ERROR;
 DROP SCHEMA multi_insert_select CASCADE;
diff --git a/src/test/regress/sql/multi_insert_select_non_pushable_queries.sql b/src/test/regress/sql/multi_insert_select_non_pushable_queries.sql
index b4654144b..539024141 100644
--- a/src/test/regress/sql/multi_insert_select_non_pushable_queries.sql
+++ b/src/test/regress/sql/multi_insert_select_non_pushable_queries.sql
@@ -4,6 +4,9 @@
 ------------------------------------
 ------------------------------------
 
+CREATE SCHEMA multi_insert_select_non_pushable_queries;
+SET search_path = multi_insert_select_non_pushable_queries,public;
+
 -- not pushable since the JOIN is not an equi join
 INSERT INTO agg_results_third (user_id, value_1_agg)
 SELECT user_id, array_length(events_table, 1)
@@ -716,3 +719,16 @@ FROM (
         GROUP BY user_id
 ) AS shard_union
 ORDER BY user_lastseen DESC;
+
+CREATE TABLE dist_table_1(id int);
+SELECT create_distributed_table('dist_table_1','id');
+CREATE TABLE dist_table_2(id int, id2 int);
+SELECT create_distributed_table('dist_table_2','id2');
+
+-- verify that insert select with union can be pulled to coordinator. We cannot push down the query
+-- since UNION clause has no FROM clause at top level query.
+SELECT coordinator_plan($$
+  EXPLAIN (COSTS FALSE) INSERT INTO dist_table_1(id) SELECT id FROM dist_table_1 UNION SELECT id FROM dist_table_2;
+$$);
+
+DROP SCHEMA multi_insert_select_non_pushable_queries CASCADE;