Handle joins between local/reference/cte via router planner

src/backend/distributed/executor/citus_custom_scan.c

@@ -541,8 +541,11 @@ RegenerateTaskForFasthPathQuery(Job *workerJob)
 
 	UpdateRelationToShardNames((Node *) workerJob->jobQuery, relationShardList);
 
+	/* fast path queries cannot have local tables */
+	bool hasLocalRelation = false;
+
 	List *placementList =
-		FindRouterWorkerList(shardIntervalList, shardsPresent, true);
+		FindRouterWorkerList(shardIntervalList, shardsPresent, true, hasLocalRelation);
 	uint64 shardId = INVALID_SHARD_ID;
 
 	if (shardsPresent)

src/backend/distributed/planner/deparse_shard_query.c

@@ -236,6 +236,12 @@ UpdateRelationToShardNames(Node *node, List *relationShardList)
 		return false;
 	}
 
+	if (!IsCitusTable(newRte->relid))
+	{
+		/* leave local tables as is */
+		return false;
+	}
+
 	/*
 	 * Search for the restrictions associated with the RTE. There better be
 	 * some, otherwise this query wouldn't be eligible as a router query.

src/backend/distributed/planner/distributed_planner.c

@@ -119,9 +119,6 @@ static PlannerRestrictionContext * CurrentPlannerRestrictionContext(void);
 static void PopPlannerRestrictionContext(void);
 static void ResetPlannerRestrictionContext(
 	PlannerRestrictionContext *plannerRestrictionContext);
-static bool IsLocalReferenceTableJoin(Query *parse, List *rangeTableList);
-static bool QueryIsNotSimpleSelect(Node *node);
-static void UpdateReferenceTablesWithShard(List *rangeTableList);
 static PlannedStmt * PlanFastPathDistributedStmt(DistributedPlanningContext *planContext,
 												 Node *distributionKeyValue);
 static PlannedStmt * PlanDistributedStmt(DistributedPlanningContext *planContext,
@@ -147,24 +144,10 @@ distributed_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	}
 	else if (CitusHasBeenLoaded())
 	{
-		if (IsLocalReferenceTableJoin(parse, rangeTableList))
+		needsDistributedPlanning = ListContainsDistributedTableRTE(rangeTableList);
+		if (needsDistributedPlanning)
 		{
-			/*
+			fastPathRouterQuery = FastPathRouterQuery(parse, &distributionKeyValue);
-			 * For joins between reference tables and local tables, we replace
-			 * reference table names with shard tables names in the query, so
-			 * we can use the standard_planner for planning it locally.
-			 */
-			UpdateReferenceTablesWithShard(rangeTableList);
-
-			needsDistributedPlanning = false;
-		}
-		else
-		{
-			needsDistributedPlanning = ListContainsDistributedTableRTE(rangeTableList);
-			if (needsDistributedPlanning)
-			{
-				fastPathRouterQuery = FastPathRouterQuery(parse, &distributionKeyValue);
-			}
 		}
 	}
 
@@ -2309,148 +2292,3 @@ HasUnresolvedExternParamsWalker(Node *expression, ParamListInfo boundParams)
 									  boundParams);
 	}
 }
-
-
-/*
- * IsLocalReferenceTableJoin returns if the given query is a join between
- * reference tables and local tables.
- */
-static bool
-IsLocalReferenceTableJoin(Query *parse, List *rangeTableList)
-{
-	bool hasReferenceTable = false;
-	bool hasLocalTable = false;
-	ListCell *rangeTableCell = false;
-
-	bool hasReferenceTableReplica = false;
-
-	/*
-	 * We only allow join between reference tables and local tables in the
-	 * coordinator.
-	 */
-	if (!IsCoordinator())
-	{
-		return false;
-	}
-
-	/*
-	 * All groups that have pg_dist_node entries, also have reference
-	 * table replicas.
-	 */
-	PrimaryNodeForGroup(COORDINATOR_GROUP_ID, &hasReferenceTableReplica);
-
-	/*
-	 * If reference table doesn't have replicas on the coordinator, we don't
-	 * allow joins with local tables.
-	 */
-	if (!hasReferenceTableReplica)
-	{
-		return false;
-	}
-
-	if (FindNodeCheck((Node *) parse, QueryIsNotSimpleSelect))
-	{
-		return false;
-	}
-
-	foreach(rangeTableCell, rangeTableList)
-	{
-		RangeTblEntry *rangeTableEntry = (RangeTblEntry *) lfirst(rangeTableCell);
-
-		/*
-		 * Don't plan joins involving functions locally since we are not sure if
-		 * they do distributed accesses or not, and defaulting to local planning
-		 * might break transactional semantics.
-		 *
-		 * For example, access to the reference table in the function might go
-		 * over a connection, but access to the same reference table outside
-		 * the function will go over the current backend. The snapshot for the
-		 * connection in the function is taken after the statement snapshot,
-		 * so they can see two different views of data.
-		 *
-		 * Looking at gram.y, RTE_TABLEFUNC is used only for XMLTABLE() which
-		 * is okay to be planned locally, so allowing that.
-		 */
-		if (rangeTableEntry->rtekind == RTE_FUNCTION)
-		{
-			return false;
-		}
-
-		if (rangeTableEntry->rtekind != RTE_RELATION)
-		{
-			continue;
-		}
-
-		/*
-		 * We only allow local join for the relation kinds for which we can
-		 * determine deterministically that access to them are local or distributed.
-		 * For this reason, we don't allow non-materialized views.
-		 */
-		if (rangeTableEntry->relkind == RELKIND_VIEW)
-		{
-			return false;
-		}
-
-		if (!IsCitusTable(rangeTableEntry->relid))
-		{
-			hasLocalTable = true;
-			continue;
-		}
-
-		CitusTableCacheEntry *cacheEntry = GetCitusTableCacheEntry(
-			rangeTableEntry->relid);
-		if (cacheEntry->partitionMethod == DISTRIBUTE_BY_NONE)
-		{
-			hasReferenceTable = true;
-		}
-		else
-		{
-			return false;
-		}
-	}
-
-	return hasLocalTable && hasReferenceTable;
-}
-
-
-/*
- * QueryIsNotSimpleSelect returns true if node is a query which modifies or
- * marks for modifications.
- */
-static bool
-QueryIsNotSimpleSelect(Node *node)
-{
-	if (!IsA(node, Query))
-	{
-		return false;
-	}
-
-	Query *query = (Query *) node;
-	return (query->commandType != CMD_SELECT) || (query->rowMarks != NIL);
-}
-
-
-/*
- * UpdateReferenceTablesWithShard recursively replaces the reference table names
- * in the given range table list with the local shard table names.
- */
-static void
-UpdateReferenceTablesWithShard(List *rangeTableList)
-{
-	List *referenceTableRTEList = ExtractReferenceTableRTEList(rangeTableList);
-
-	RangeTblEntry *rangeTableEntry = NULL;
-	foreach_ptr(rangeTableEntry, referenceTableRTEList)
-	{
-		Oid referenceTableLocalShardOid = GetReferenceTableLocalShardOid(
-			rangeTableEntry->relid);
-
-		rangeTableEntry->relid = referenceTableLocalShardOid;
-
-		/*
-		 * Parser locks relations in addRangeTableEntry(). So we should lock the
-		 * modified ones too.
-		 */
-		LockRelationOid(referenceTableLocalShardOid, AccessShareLock);
-	}
-}

src/backend/distributed/planner/multi_router_planner.c

@@ -45,6 +45,7 @@
 #include "distributed/citus_ruleutils.h"
 #include "distributed/query_pushdown_planning.h"
 #include "distributed/query_utils.h"
+#include "distributed/reference_table_utils.h"
 #include "distributed/relation_restriction_equivalence.h"
 #include "distributed/relay_utility.h"
 #include "distributed/resource_lock.h"
@@ -154,7 +155,7 @@ static List * ExtractInsertValuesList(Query *query, Var *partitionColumn);
 static DeferredErrorMessage * MultiRouterPlannableQuery(Query *query);
 static DeferredErrorMessage * ErrorIfQueryHasUnroutableModifyingCTE(Query *queryTree);
 static bool SelectsFromDistributedTable(List *rangeTableList, Query *query);
-static ShardPlacement * CreateDummyPlacement(void);
+static ShardPlacement * CreateDummyPlacement(bool hasLocalRelation);
 static List * get_all_actual_clauses(List *restrictinfo_list);
 static int CompareInsertValuesByShardId(const void *leftElement,
 										const void *rightElement);
@@ -2021,6 +2022,8 @@ PlanRouterQuery(Query *originalQuery,
 				bool replacePrunedQueryWithDummy, bool *multiShardModifyQuery,
 				Const **partitionValueConst)
 {
+	RelationRestrictionContext *relationRestrictionContext =
+		plannerRestrictionContext->relationRestrictionContext;
 	bool isMultiShardQuery = false;
 	DeferredErrorMessage *planningError = NULL;
 	bool shardsPresent = false;
@@ -2133,9 +2136,11 @@ PlanRouterQuery(Query *originalQuery,
 	/* we need anchor shard id for select queries with router planner */
 	uint64 shardId = GetAnchorShardId(*prunedShardIntervalListList);
 
+	bool hasLocalRelation = relationRestrictionContext->hasLocalRelation;
+
 	List *workerList =
 		FindRouterWorkerList(*prunedShardIntervalListList, shardsPresent,
-							 replacePrunedQueryWithDummy);
+							 replacePrunedQueryWithDummy, hasLocalRelation);
 
 	if (workerList == NIL)
 	{
@@ -2166,9 +2171,9 @@ PlanRouterQuery(Query *originalQuery,
 
 List *
 FindRouterWorkerList(List *shardIntervalList, bool shardsPresent,
-					 bool replacePrunedQueryWithDummy)
+					 bool replacePrunedQueryWithDummy, bool hasLocalRelation)
 {
-	List *workerList = NIL;
+	List *placementList = NIL;
 
 	/*
 	 * Determine the worker that has all shard placements if a shard placement found.
@@ -2178,18 +2183,38 @@ FindRouterWorkerList(List *shardIntervalList, bool shardsPresent,
 	 */
 	if (shardsPresent)
 	{
-		workerList = WorkersContainingAllShards(shardIntervalList);
+		List *workerList = WorkersContainingAllShards(shardIntervalList);
+
+		if (hasLocalRelation)
+		{
+			ShardPlacement *taskPlacement = NULL;
+
+			/*
+			 * If there is a local table, we only allow the local placement to
+			 * be used. If there is none, we disallow the query.
+			 */
+			foreach_ptr(taskPlacement, workerList)
+			{
+				/* include only the local placement */
+				if (taskPlacement->groupId == GetLocalGroupId())
+				{
+					placementList = lappend(placementList, taskPlacement);
+				}
+			}
+		}
+		else
+		{
+			placementList = workerList;
+		}
 	}
 	else if (replacePrunedQueryWithDummy)
 	{
-		ShardPlacement *dummyPlacement = CreateDummyPlacement();
+		ShardPlacement *dummyPlacement = CreateDummyPlacement(hasLocalRelation);
-		if (dummyPlacement != NULL)
+
-		{
+		placementList = list_make1(dummyPlacement);
-			workerList = lappend(workerList, dummyPlacement);
-		}
 	}
 
-	return workerList;
+	return placementList;
 }
 
 
@@ -2201,14 +2226,17 @@ FindRouterWorkerList(List *shardIntervalList, bool shardsPresent,
  *
  * If round robin policy is set, the placement could be on any node in pg_dist_node.
  * Else, the local node is set for the placement.
+ *
+ * Queries can also involve local tables. In that case we always use the local
+ * node.
  */
 static ShardPlacement *
-CreateDummyPlacement(void)
+CreateDummyPlacement(bool hasLocalRelation)
 {
 	static uint32 zeroShardQueryRoundRobin = 0;
 	ShardPlacement *dummyPlacement = CitusMakeNode(ShardPlacement);
 
-	if (TaskAssignmentPolicy == TASK_ASSIGNMENT_ROUND_ROBIN)
+	if (TaskAssignmentPolicy == TASK_ASSIGNMENT_ROUND_ROBIN && !hasLocalRelation)
 	{
 		List *workerNodeList = ActiveReadableWorkerNodeList();
 		if (workerNodeList == NIL)
@@ -2441,6 +2469,13 @@ TargetShardIntervalsForRestrictInfo(RelationRestrictionContext *restrictionConte
 		RelationRestriction *relationRestriction =
 			(RelationRestriction *) lfirst(restrictionCell);
 		Oid relationId = relationRestriction->relationId;
+
+		if (!IsCitusTable(relationId))
+		{
+			/* ignore local tables for shard pruning purposes */
+			continue;
+		}
+
 		Index tableId = relationRestriction->index;
 		CitusTableCacheEntry *cacheEntry = GetCitusTableCacheEntry(relationId);
 		int shardCount = cacheEntry->shardIntervalArrayLength;
@@ -3197,22 +3232,22 @@ MultiRouterPlannableQuery(Query *query)
 							 NULL, NULL);
 	}
 
+	bool hasLocalTable = false;
+	bool hasDistributedTable = false;
+
 	ExtractRangeTableRelationWalker((Node *) query, &rangeTableRelationList);
 	foreach(rangeTableRelationCell, rangeTableRelationList)
 	{
 		RangeTblEntry *rte = (RangeTblEntry *) lfirst(rangeTableRelationCell);
 		if (rte->rtekind == RTE_RELATION)
 		{
-			/* only hash partitioned tables are supported */
 			Oid distributedTableId = rte->relid;
 
+			/* local tables are allowed if there are no distributed tables */
 			if (!IsCitusTable(distributedTableId))
 			{
-				/* local tables cannot be read from workers */
+				hasLocalTable = true;
-				return DeferredError(
+				continue;
-					ERRCODE_FEATURE_NOT_SUPPORTED,
-					"Local tables cannot be used in distributed queries.",
-					NULL, NULL);
 			}
 
 			char partitionMethod = PartitionMethod(distributedTableId);
@@ -3225,6 +3260,11 @@ MultiRouterPlannableQuery(Query *query)
 					NULL, NULL);
 			}
 
+			if (partitionMethod != DISTRIBUTE_BY_NONE)
+			{
+				hasDistributedTable = true;
+			}
+
 			/*
 			 * Currently, we don't support tables with replication factor > 1,
 			 * except reference tables with SELECT ... FOR UPDATE queries. It is
@@ -3246,6 +3286,14 @@ MultiRouterPlannableQuery(Query *query)
 		}
 	}
 
+	/* local tables are allowed if there are no distributed tables */
+	if (hasLocalTable && hasDistributedTable)
+	{
+		return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
+							 "Local tables cannot be used in distributed queries.",
+							 NULL, NULL);
+	}
+
 	return ErrorIfQueryHasUnroutableModifyingCTE(query);
 }
 

src/include/distributed/multi_router_planner.h

@@ -46,7 +46,8 @@ extern DeferredErrorMessage * PlanRouterQuery(Query *originalQuery,
 extern List * RelationShardListForShardIntervalList(List *shardIntervalList,
 													bool *shardsPresent);
 extern List * FindRouterWorkerList(List *shardIntervalList, bool shardsPresent,
-								   bool replacePrunedQueryWithDummy);
+								   bool replacePrunedQueryWithDummy,
+								   bool hasLocalRelation);
 extern List * RouterInsertTaskList(Query *query, bool parametersInQueryResolved,
 								   DeferredErrorMessage **planningError);
 extern Const * ExtractInsertPartitionKeyValue(Query *query);

src/test/regress/expected/coordinator_shouldhaveshards.out

@@ -231,6 +231,7 @@ NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinato
 (1 row)
 
 SELECT * FROM ref JOIN local ON (a = x);
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
  a | b | x | y
 ---------------------------------------------------------------------
 (0 rows)
@@ -250,6 +251,7 @@ NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinato
 TRUNCATE ref;
 NOTICE:  executing the command locally: TRUNCATE TABLE coordinator_shouldhaveshards.ref_xxxxx CASCADE
 SELECT * FROM ref JOIN local ON (a = x);
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
  a | b | x | y
 ---------------------------------------------------------------------
 (0 rows)
@@ -268,6 +270,7 @@ INSERT INTO ref VALUES (1,2);
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (1, 2)
 INSERT INTO local VALUES (1,2);
 SELECT * FROM ref JOIN local ON (a = x);
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
  a | b | x | y
 ---------------------------------------------------------------------
  1 | 2 | 1 | 2
@@ -290,6 +293,7 @@ WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETU
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503000 test WHERE true
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503003 test WHERE true
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (3, 2) RETURNING a, b
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
 NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.count FROM (SELECT intermediate_result.count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) a, (SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) b, (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) c, (SELECT intermediate_result.count FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) d ORDER BY b.x, b.y, c.a, c.b
  count | x | y | a | b | count
 ---------------------------------------------------------------------
@@ -299,6 +303,7 @@ NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.co
 TRUNCATE ref;
 NOTICE:  executing the command locally: TRUNCATE TABLE coordinator_shouldhaveshards.ref_xxxxx CASCADE
 SELECT * FROM ref JOIN local ON (a = x);
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
  a | b | x | y
 ---------------------------------------------------------------------
 (0 rows)
@@ -309,6 +314,7 @@ WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETU
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503000 test WHERE true
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503003 test WHERE true
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (3, 2) RETURNING a, b
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
 NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.count FROM (SELECT intermediate_result.count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) a, (SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) b, (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) c, (SELECT intermediate_result.count FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) d ORDER BY b.x, b.y, c.a, c.b
  count | x | y | a | b | count
 ---------------------------------------------------------------------
@@ -323,6 +329,7 @@ WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETU
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503000 test WHERE true
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503003 test WHERE true
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (3, 2) RETURNING a, b
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
 NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.count FROM (SELECT intermediate_result.count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) a, (SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) b, (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) c, (SELECT intermediate_result.count FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) d ORDER BY b.x, b.y, c.a, c.b
  count | x | y | a | b | count
 ---------------------------------------------------------------------
@@ -337,6 +344,7 @@ WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETU
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503000 test WHERE true
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503003 test WHERE true
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 AS citus_table_alias (a, b) SELECT a, b FROM read_intermediate_result('insert_select_XXX_1503016'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer) RETURNING citus_table_alias.a, citus_table_alias.b
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
 NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.count FROM (SELECT intermediate_result.count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) a, (SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) b, (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) c, (SELECT intermediate_result.count FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) d ORDER BY b.x, b.y, c.a, c.b
  count | x | y | a  | b  | count
 ---------------------------------------------------------------------
@@ -358,6 +366,7 @@ INSERT INTO ref VALUES (1,2);
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (1, 2)
 INSERT INTO local VALUES (1,2);
 SELECT * FROM ref JOIN local ON (a = x);
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
  a | b | x | y
 ---------------------------------------------------------------------
  1 | 2 | 1 | 2
@@ -369,14 +378,14 @@ WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETU
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503000 test WHERE true
 NOTICE:  executing the command locally: SELECT count(*) AS count FROM coordinator_shouldhaveshards.test_1503003 test WHERE true
 NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.ref_1503016 (a, b) VALUES (3, 2) RETURNING a, b
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x)))
 NOTICE:  executing the command locally: SELECT a.count, b.x, b.y, c.a, c.b, d.count FROM (SELECT intermediate_result.count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) a, (SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) b, (SELECT intermediate_result.a, intermediate_result.b FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(a integer, b integer)) c, (SELECT intermediate_result.count FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(count bigint)) d ORDER BY b.x, b.y, c.a, c.b
  count | x | y | a | b | count
 ---------------------------------------------------------------------
    100 | 3 | 2 | 3 | 2 |     1
 (1 row)
 
--- issue #3801
+-- joins between local tables and distributed tables are disallowed
-SET citus.shard_replication_factor TO 2;
 CREATE TABLE dist_table(a int);
 ERROR:  relation "dist_table" already exists
 SELECT create_distributed_table('dist_table', 'a');
@@ -389,6 +398,42 @@ HINT:  To remove the local data, run: SELECT truncate_local_data_after_distribut
 
 (1 row)
 
+INSERT INTO dist_table VALUES(1);
+NOTICE:  executing the command locally: INSERT INTO coordinator_shouldhaveshards.dist_table_1503017 (a) VALUES (1)
+SELECT * FROM local JOIN dist_table ON (a = x);
+ERROR:  relation local is not distributed
+SELECT * FROM local JOIN dist_table ON (a = x) WHERE a = 1;;
+ERROR:  relation local is not distributed
+-- intermediate results are allowed
+WITH cte_1 AS (SELECT * FROM dist_table LIMIT 1)
+SELECT * FROM ref JOIN local ON (a = x) JOIN cte_1 ON (local.x = cte_1.a);
+NOTICE:  executing the command locally: SELECT a FROM coordinator_shouldhaveshards.dist_table_1503017 dist_table WHERE true LIMIT '1'::bigint
+NOTICE:  executing the command locally: SELECT a FROM coordinator_shouldhaveshards.dist_table_1503020 dist_table WHERE true LIMIT '1'::bigint
+NOTICE:  executing the command locally: SELECT ref.a, ref.b, local.x, local.y, cte_1.a FROM ((coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x))) JOIN (SELECT intermediate_result.a FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(a integer)) cte_1 ON ((local.x OPERATOR(pg_catalog.=) cte_1.a)))
+ a | b | x | y | a
+---------------------------------------------------------------------
+ 1 | 2 | 1 | 2 | 1
+(1 row)
+
+-- full router query with CTE and local
+WITH cte_1 AS (SELECT * FROM ref LIMIT 1)
+SELECT * FROM ref JOIN local ON (a = x) JOIN cte_1 ON (local.x = cte_1.a);
+NOTICE:  executing the command locally: WITH cte_1 AS (SELECT ref_1.a, ref_1.b FROM coordinator_shouldhaveshards.ref_1503016 ref_1 LIMIT 1) SELECT ref.a, ref.b, local.x, local.y, cte_1.a, cte_1.b FROM ((coordinator_shouldhaveshards.ref_1503016 ref JOIN coordinator_shouldhaveshards.local ON ((ref.a OPERATOR(pg_catalog.=) local.x))) JOIN cte_1 ON ((local.x OPERATOR(pg_catalog.=) cte_1.a)))
+ a | b | x | y | a | b
+---------------------------------------------------------------------
+ 1 | 2 | 1 | 2 | 1 | 2
+(1 row)
+
+DROP TABLE dist_table;
+-- issue #3801
+SET citus.shard_replication_factor TO 2;
+CREATE TABLE dist_table(a int);
+SELECT create_distributed_table('dist_table', 'a');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
 BEGIN;
 -- this will use perPlacementQueryStrings, make sure it works correctly with
 -- copying task
@@ -400,10 +445,10 @@ CREATE TABLE dist_table1(a int);
 -- this will use queryStringList, make sure it works correctly with
 -- copying task
 SELECT create_distributed_table('dist_table1', 'a');
-NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503023, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503023, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
+NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503029, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503029, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
-NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503025, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503025, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
+NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503031, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503031, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
-NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503026, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503026, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
+NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503032, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503032, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
-NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503028, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503028, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
+NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (1503034, 'coordinator_shouldhaveshards', 'CREATE TABLE coordinator_shouldhaveshards.dist_table1 (a integer)');SELECT worker_apply_shard_ddl_command (1503034, 'coordinator_shouldhaveshards', 'ALTER TABLE coordinator_shouldhaveshards.dist_table1 OWNER TO postgres')
  create_distributed_table
 ---------------------------------------------------------------------
 

src/test/regress/expected/local_shard_copy.out

@@ -456,6 +456,7 @@ TRUNCATE TABLE reference_table;
 NOTICE:  executing the command locally: TRUNCATE TABLE local_shard_copy.reference_table_xxxxx CASCADE
 TRUNCATE TABLE local_table;
 SELECT count(*) FROM reference_table, local_table WHERE reference_table.key = local_table.key;
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM local_shard_copy.reference_table_1570000 reference_table, local_shard_copy.local_table WHERE (reference_table.key OPERATOR(pg_catalog.=) local_table.key)
  count
 ---------------------------------------------------------------------
      0

src/test/regress/expected/locally_execute_intermediate_results.out

@@ -2,13 +2,11 @@ CREATE SCHEMA locally_execute_intermediate_results;
 SET search_path TO locally_execute_intermediate_results;
 SET citus.log_intermediate_results TO TRUE;
 SET citus.log_local_commands TO TRUE;
-SET client_min_messages TO DEBUG1;
 SET citus.shard_count TO 4;
 SET citus.next_shard_id TO 1580000;
 SET citus.shard_replication_factor TO 1;
 SET citus.replication_model TO 'streaming';
 CREATE TABLE table_1 (key int, value text);
-DEBUG:  building index "pg_toast_xxxxx_index" on table "pg_toast_xxxxx" serially
 SELECT create_distributed_table('table_1', 'key');
  create_distributed_table
 ---------------------------------------------------------------------
@@ -16,7 +14,6 @@ SELECT create_distributed_table('table_1', 'key');
 (1 row)
 
 CREATE TABLE table_2 (key int, value text);
-DEBUG:  building index "pg_toast_xxxxx_index" on table "pg_toast_xxxxx" serially
 SELECT create_distributed_table('table_2', 'key');
  create_distributed_table
 ---------------------------------------------------------------------
@@ -24,22 +21,24 @@ SELECT create_distributed_table('table_2', 'key');
 (1 row)
 
 CREATE TABLE ref_table (key int, value text);
-DEBUG:  building index "pg_toast_xxxxx_index" on table "pg_toast_xxxxx" serially
 SELECT create_reference_table('ref_table');
  create_reference_table
 ---------------------------------------------------------------------
 
 (1 row)
 
+CREATE TABLE local_table (key int, value text);
 -- load some data
 INSERT INTO table_1    VALUES (1, '1'), (2, '2'), (3, '3'), (4, '4');
 INSERT INTO table_2    VALUES                     (3, '3'), (4, '4'), (5, '5'), (6, '6');
 INSERT INTO ref_table  VALUES (1, '1'), (2, '2'), (3, '3'), (4, '4'), (5, '5'), (6, '6');
 NOTICE:  executing the command locally: INSERT INTO locally_execute_intermediate_results.ref_table_1580008 AS citus_table_alias (key, value) VALUES (1,'1'::text), (2,'2'::text), (3,'3'::text), (4,'4'::text), (5,'5'::text), (6,'6'::text)
+INSERT INTO local_table VALUES                    (3, '3'), (4, '4'), (5, '5'), (6, '6');
 -- prevent PG 11 - PG 12 outputs to diverge
 -- and have a lot more CTEs recursively planned for the
 -- sake of increasing the test coverage
 SET citus.enable_cte_inlining TO false;
+SET client_min_messages TO DEBUG1;
 -- the query cannot be executed locally, but still because of
 -- HAVING the intermediate result is written to local file as well
 WITH cte_1 AS (SELECT max(value) FROM table_1)
@@ -462,6 +461,49 @@ NOTICE:  executing the command locally: SELECT foo.key, bar.key FROM (SELECT int
 ---------------------------------------------------------------------
 (0 rows)
 
+-- queries in which the last step has only CTEs can use local tables
+WITH cte_1 AS (SELECT max(value) FROM table_1)
+SELECT
+count(*)
+FROM
+local_table
+GROUP BY key
+HAVING max(value) > (SELECT max FROM cte_1);
+DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT max(value) AS max FROM locally_execute_intermediate_results.table_1
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM locally_execute_intermediate_results.local_table GROUP BY key HAVING (max(value) OPERATOR(pg_catalog.>) (SELECT cte_1.max FROM (SELECT intermediate_result.max FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(max text)) cte_1))
+DEBUG:  Subplan XXX_1 will be written to local file
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM locally_execute_intermediate_results.local_table GROUP BY key HAVING (max(value) OPERATOR(pg_catalog.>) (SELECT cte_1.max FROM (SELECT intermediate_result.max FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(max text)) cte_1))
+ count
+---------------------------------------------------------------------
+     1
+     1
+(2 rows)
+
+WITH cte_1 AS (SELECT max(value) FROM table_1),
+cte_2 AS (SELECT * FROM table_2)
+SELECT
+count(*)
+FROM
+local_table
+WHERE
+key > (SELECT key FROM cte_2 ORDER BY 1 LIMIT 1)
+GROUP BY key
+HAVING max(value) > (SELECT max FROM cte_1);
+DEBUG:  generating subplan XXX_1 for CTE cte_1: SELECT max(value) AS max FROM locally_execute_intermediate_results.table_1
+DEBUG:  generating subplan XXX_2 for CTE cte_2: SELECT key, value FROM locally_execute_intermediate_results.table_2
+DEBUG:  generating subplan XXX_3 for subquery SELECT key 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)) cte_2 ORDER BY key LIMIT 1
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM locally_execute_intermediate_results.local_table WHERE (key OPERATOR(pg_catalog.>) (SELECT intermediate_result.key FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(key integer))) GROUP BY key HAVING (max(value) OPERATOR(pg_catalog.>) (SELECT cte_1.max FROM (SELECT intermediate_result.max FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(max text)) cte_1))
+DEBUG:  Subplan XXX_1 will be written to local file
+DEBUG:  Subplan XXX_2 will be written to local file
+DEBUG:  Subplan XXX_3 will be written to local file
+NOTICE:  executing the command locally: SELECT key 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)) cte_2 ORDER BY key LIMIT 1
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM locally_execute_intermediate_results.local_table WHERE (key OPERATOR(pg_catalog.>) (SELECT intermediate_result.key FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(key integer))) GROUP BY key HAVING (max(value) OPERATOR(pg_catalog.>) (SELECT cte_1.max FROM (SELECT intermediate_result.max FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(max text)) cte_1))
+ count
+---------------------------------------------------------------------
+     1
+     1
+(2 rows)
+
 \c - - - :worker_1_port
 -- now use the same queries on a worker
 SET search_path TO locally_execute_intermediate_results;

src/test/regress/expected/multi_modifications.out

@@ -1298,10 +1298,9 @@ DELETE FROM summary_table WHERE (
     SELECT 1 FROM pg_catalog.pg_statio_sys_sequences
 ) = null;
 DELETE FROM summary_table WHERE (
-    SELECT (select action_statement from information_schema.triggers)
+    SELECT (select min(action_statement) from information_schema.triggers)
     FROM pg_catalog.pg_statio_sys_sequences
 ) = null;
-ERROR:  relation pg_namespace is not distributed
 DELETE FROM summary_table WHERE id < (
     SELECT 0 FROM pg_dist_node
 );

src/test/regress/expected/multi_mx_add_coordinator.out

@@ -137,11 +137,15 @@ SET search_path TO mx_add_coordinator,public;
 INSERT INTO ref VALUES (1), (2), (3);
 UPDATE ref SET a = a + 1;
 DELETE FROM ref WHERE a > 3;
--- Test we don't allow reference/local joins on mx workers
+-- Test we allow reference/local joins on mx workers
 CREATE TABLE local_table (a int);
 INSERT INTO local_table VALUES (2), (4);
 SELECT r.a FROM ref r JOIN local_table lt on r.a = lt.a;
-ERROR:  relation local_table is not distributed
+ a
+---------------------------------------------------------------------
+ 2
+(1 row)
+
 \c - - - :master_port
 SET search_path TO mx_add_coordinator,public;
 SELECT * FROM ref ORDER BY a;

src/test/regress/expected/replicate_reference_tables_to_coordinator.out

@@ -99,20 +99,26 @@ SELECT citus_table_is_visible('numbers_8000001'::regclass::oid);
 -- Join between reference tables and local tables
 CREATE TABLE local_table(a int);
 INSERT INTO local_table VALUES (2), (4), (7), (20);
-EXPLAIN SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers;
+EXPLAIN (COSTS OFF) SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers;
-                                  QUERY PLAN
+                         QUERY PLAN
 ---------------------------------------------------------------------
- Merge Join  (cost=359.57..860.00 rows=32512 width=8)
+ Custom Scan (Citus Adaptive)
-   Merge Cond: (local_table.a = numbers_8000001.a)
+   Task Count: 1
-   ->  Sort  (cost=179.78..186.16 rows=2550 width=4)
+   Tasks Shown: All
-         Sort Key: local_table.a
+   ->  Task
-         ->  Seq Scan on local_table  (cost=0.00..35.50 rows=2550 width=4)
+         Node: host=localhost port=xxxxx dbname=regression
-   ->  Sort  (cost=179.78..186.16 rows=2550 width=4)
+         ->  Merge Join
-         Sort Key: numbers_8000001.a
+               Merge Cond: (local_table.a = numbers.a)
-         ->  Seq Scan on numbers_8000001  (cost=0.00..35.50 rows=2550 width=4)
+               ->  Sort
-(8 rows)
+                     Sort Key: local_table.a
+                     ->  Seq Scan on local_table
+               ->  Sort
+                     Sort Key: numbers.a
+                     ->  Seq Scan on numbers_8000001 numbers
+(13 rows)
 
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers ORDER BY 1;
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) ORDER BY local_table.a
  a  | a
 ---------------------------------------------------------------------
  20 | 20
@@ -123,6 +129,7 @@ SELECT lt.a, sq.a, sq.b
 FROM local_table lt
 JOIN squares sq ON sq.a > lt.a and sq.b > 90
 ORDER BY 1,2,3;
+NOTICE:  executing the command locally: SELECT lt.a, sq.a, sq.b FROM (replicate_ref_to_coordinator.local_table lt JOIN replicate_ref_to_coordinator.squares_8000000 sq ON (((sq.a OPERATOR(pg_catalog.>) lt.a) AND (sq.b OPERATOR(pg_catalog.>) 90)))) ORDER BY lt.a, sq.a, sq.b
  a | a  |  b
 ---------------------------------------------------------------------
  2 | 10 | 100
@@ -133,6 +140,7 @@ ORDER BY 1,2,3;
 -- should work if in transaction block
 BEGIN;
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers ORDER BY 1;
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) ORDER BY local_table.a
  a  | a
 ---------------------------------------------------------------------
  20 | 20
@@ -145,6 +153,9 @@ BEGIN
 	PERFORM local_table.a, numbers.a FROM local_table NATURAL JOIN numbers;
 END;
 $$;
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a))
+CONTEXT:  SQL statement "SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers"
+PL/pgSQL function inline_code_block line 3 at PERFORM
 -- test plpgsql function
 CREATE FUNCTION test_reference_local_join_plpgsql_func()
 RETURNS void AS $$
@@ -160,6 +171,9 @@ SELECT test_reference_local_join_plpgsql_func();
 NOTICE:  executing the command locally: INSERT INTO replicate_ref_to_coordinator.numbers_8000001 (a) VALUES (4)
 CONTEXT:  SQL statement "INSERT INTO numbers VALUES (4)"
 PL/pgSQL function test_reference_local_join_plpgsql_func() line 4 at SQL statement
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) ORDER BY local_table.a
+CONTEXT:  SQL statement "SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers ORDER BY 1"
+PL/pgSQL function test_reference_local_join_plpgsql_func() line 5 at PERFORM
 ERROR:
 CONTEXT:  PL/pgSQL function test_reference_local_join_plpgsql_func() line 6 at RAISE
 SELECT sum(a) FROM local_table;
@@ -180,6 +194,8 @@ CREATE PROCEDURE test_reference_local_join_proc() AS $$
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers ORDER BY 1;
 $$ LANGUAGE sql;
 CALL test_reference_local_join_proc();
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) ORDER BY local_table.a
+CONTEXT:  SQL function "test_reference_local_join_proc" statement 1
 CREATE SCHEMA s1;
 CREATE TABLE s1.ref(a int);
 SELECT create_reference_table('s1.ref');
@@ -190,6 +206,7 @@ SELECT create_reference_table('s1.ref');
 
 BEGIN;
 SELECT local_table.a, r.a FROM local_table NATURAL JOIN s1.ref r ORDER BY 1;
+NOTICE:  executing the command locally: SELECT local_table.a, r.a FROM (replicate_ref_to_coordinator.local_table JOIN s1.ref_8000002 r(a) USING (a)) ORDER BY local_table.a
  a | a
 ---------------------------------------------------------------------
 (0 rows)
@@ -199,6 +216,7 @@ BEGIN;
 WITH t1 AS (
 	SELECT my_volatile_fn() r, a FROM local_table
 ) SELECT count(*) FROM t1, numbers WHERE t1.a = numbers.a AND r < 0.5;
+NOTICE:  executing the command locally: WITH t1 AS (SELECT replicate_ref_to_coordinator.my_volatile_fn() AS r, local_table.a FROM replicate_ref_to_coordinator.local_table) SELECT count(*) AS count FROM t1, replicate_ref_to_coordinator.numbers_8000001 numbers WHERE ((t1.a OPERATOR(pg_catalog.=) numbers.a) AND ((t1.r)::numeric OPERATOR(pg_catalog.<) 0.5))
  count
 ---------------------------------------------------------------------
      0
@@ -209,6 +227,7 @@ BEGIN;
 WITH t1 AS (
 	SELECT my_volatile_fn() r, a FROM numbers
 ) SELECT count(*) FROM t1, local_table WHERE t1.a = local_table.a AND r < 0.5;
+NOTICE:  executing the command locally: WITH t1 AS (SELECT replicate_ref_to_coordinator.my_volatile_fn() AS r, numbers.a FROM replicate_ref_to_coordinator.numbers_8000001 numbers) SELECT count(*) AS count FROM t1, replicate_ref_to_coordinator.local_table WHERE ((t1.a OPERATOR(pg_catalog.=) local_table.a) AND ((t1.r)::numeric OPERATOR(pg_catalog.<) 0.5))
  count
 ---------------------------------------------------------------------
      0
@@ -218,6 +237,7 @@ END;
 BEGIN;
 SELECT count(*) FROM local_table
 WHERE EXISTS(SELECT my_volatile_fn() FROM numbers WHERE local_table.a = numbers.a);
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM replicate_ref_to_coordinator.local_table WHERE (EXISTS (SELECT replicate_ref_to_coordinator.my_volatile_fn() AS my_volatile_fn FROM replicate_ref_to_coordinator.numbers_8000001 numbers WHERE (local_table.a OPERATOR(pg_catalog.=) numbers.a)))
  count
 ---------------------------------------------------------------------
      1
@@ -227,6 +247,7 @@ END;
 BEGIN;
 SELECT count(*) FROM numbers
 WHERE EXISTS(SELECT my_volatile_fn() FROM local_table WHERE local_table.a = numbers.a);
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM replicate_ref_to_coordinator.numbers_8000001 numbers WHERE (EXISTS (SELECT replicate_ref_to_coordinator.my_volatile_fn() AS my_volatile_fn FROM replicate_ref_to_coordinator.local_table WHERE (local_table.a OPERATOR(pg_catalog.=) numbers.a)))
  count
 ---------------------------------------------------------------------
      1
@@ -247,24 +268,54 @@ $$ LANGUAGE sql;
 SELECT test_reference_local_join_func();
  test_reference_local_join_func
 ---------------------------------------------------------------------
+ (2,2)
  (20,20)
-(1 row)
+(2 rows)
 
--- shouldn't plan locally if modifications happen in CTEs, ...
+-- CTEs are allowed
 WITH ins AS (INSERT INTO numbers VALUES (1) RETURNING *)
 SELECT * FROM numbers, local_table;
-ERROR:  relation local_table is not distributed
+NOTICE:  executing the command locally: INSERT INTO replicate_ref_to_coordinator.numbers_8000001 (a) VALUES (1) RETURNING a
+NOTICE:  executing the command locally: SELECT numbers.a, local_table.a FROM replicate_ref_to_coordinator.numbers_8000001 numbers, replicate_ref_to_coordinator.local_table
+ a  | a
+---------------------------------------------------------------------
+ 20 |  2
+ 20 |  4
+ 20 |  7
+ 20 | 20
+ 21 |  2
+ 21 |  4
+ 21 |  7
+ 21 | 20
+  2 |  2
+  2 |  4
+  2 |  7
+  2 | 20
+(12 rows)
+
 WITH t AS (SELECT *, my_volatile_fn() x FROM numbers FOR UPDATE)
 SELECT * FROM numbers, local_table
 WHERE EXISTS (SELECT * FROM t WHERE t.x = numbers.a);
-ERROR:  relation local_table is not distributed
+NOTICE:  executing the command locally: WITH t AS (SELECT numbers_1.a, replicate_ref_to_coordinator.my_volatile_fn() AS x FROM replicate_ref_to_coordinator.numbers_8000001 numbers_1 FOR UPDATE OF numbers_1) SELECT numbers.a, local_table.a FROM replicate_ref_to_coordinator.numbers_8000001 numbers, replicate_ref_to_coordinator.local_table WHERE (EXISTS (SELECT t.a, t.x FROM t WHERE (t.x OPERATOR(pg_catalog.=) numbers.a)))
--- but this should be fine
+ a | a
+---------------------------------------------------------------------
+ 1 |  2
+ 1 |  4
+ 1 |  7
+ 1 | 20
+(4 rows)
+
 WITH t AS (SELECT *, my_volatile_fn() x FROM numbers)
 SELECT * FROM numbers, local_table
 WHERE EXISTS (SELECT * FROM t WHERE t.x = numbers.a);
+NOTICE:  executing the command locally: WITH t AS (SELECT numbers_1.a, replicate_ref_to_coordinator.my_volatile_fn() AS x FROM replicate_ref_to_coordinator.numbers_8000001 numbers_1) SELECT numbers.a, local_table.a FROM replicate_ref_to_coordinator.numbers_8000001 numbers, replicate_ref_to_coordinator.local_table WHERE (EXISTS (SELECT t.a, t.x FROM t WHERE (t.x OPERATOR(pg_catalog.=) numbers.a)))
  a | a
 ---------------------------------------------------------------------
-(0 rows)
+ 1 |  2
+ 1 |  4
+ 1 |  7
+ 1 | 20
+(4 rows)
 
 -- shouldn't plan locally even if distributed table is in CTE or subquery
 CREATE TABLE dist(a int);
@@ -278,10 +329,13 @@ INSERT INTO dist VALUES (20),(30);
 WITH t AS (SELECT *, my_volatile_fn() x FROM dist)
 SELECT * FROM numbers, local_table
 WHERE EXISTS (SELECT * FROM t WHERE t.x = numbers.a);
-ERROR:  relation local_table is not distributed
+ERROR:  function replicate_ref_to_coordinator.my_volatile_fn() does not exist
+HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
+CONTEXT:  while executing command on localhost:xxxxx
 -- test CTE being reference/local join for distributed query
 WITH t as (SELECT n.a, my_volatile_fn() x FROM numbers n NATURAL JOIN local_table l)
 SELECT a FROM t NATURAL JOIN dist;
+NOTICE:  executing the command locally: SELECT n.a, replicate_ref_to_coordinator.my_volatile_fn() AS x FROM (replicate_ref_to_coordinator.numbers_8000001 n(a) JOIN replicate_ref_to_coordinator.local_table l USING (a))
  a
 ---------------------------------------------------------------------
  20
@@ -289,11 +343,21 @@ SELECT a FROM t NATURAL JOIN dist;
 
  -- shouldn't error if FOR UPDATE/FOR SHARE
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers FOR SHARE;
-ERROR:  could not run distributed query with FOR UPDATE/SHARE commands
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) FOR SHARE OF local_table FOR SHARE OF numbers
-HINT:  Consider using an equality filter on the distributed table's partition column.
+ a  | a
+---------------------------------------------------------------------
+  2 |  2
+ 20 | 20
+(2 rows)
+
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers FOR UPDATE;
-ERROR:  could not run distributed query with FOR UPDATE/SHARE commands
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.a FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a)) FOR UPDATE OF local_table FOR UPDATE OF numbers
-HINT:  Consider using an equality filter on the distributed table's partition column.
+ a  | a
+---------------------------------------------------------------------
+  2 |  2
+ 20 | 20
+(2 rows)
+
 --
 -- Joins between reference tables and views shouldn't be planned locally.
 --
@@ -313,14 +377,11 @@ SELECT public.coordinator_plan($Q$
 EXPLAIN (COSTS FALSE)
 	SELECT * FROM squares JOIN local_table_v ON squares.a = local_table_v.a;
 $Q$);
-                coordinator_plan
+       coordinator_plan
 ---------------------------------------------------------------------
  Custom Scan (Citus Adaptive)
-   ->  Distributed Subplan XXX_1
-         ->  Seq Scan on local_table
-               Filter: ((a >= 1) AND (a <= 10))
    Task Count: 1
-(5 rows)
+(2 rows)
 
 DROP VIEW numbers_v, local_table_v;
 --
@@ -330,31 +391,39 @@ DROP VIEW numbers_v, local_table_v;
 CREATE MATERIALIZED VIEW numbers_v AS SELECT * FROM numbers WHERE a BETWEEN 1 AND 10;
 NOTICE:  executing the command locally: SELECT a FROM replicate_ref_to_coordinator.numbers_8000001 numbers WHERE ((a OPERATOR(pg_catalog.>=) 1) AND (a OPERATOR(pg_catalog.<=) 10))
 REFRESH MATERIALIZED VIEW numbers_v;
+NOTICE:  executing the command locally: SELECT numbers.a FROM replicate_ref_to_coordinator.numbers_8000001 numbers WHERE ((numbers.a OPERATOR(pg_catalog.>=) 1) AND (numbers.a OPERATOR(pg_catalog.<=) 10))
 SELECT public.plan_is_distributed($Q$
 EXPLAIN (COSTS FALSE)
 	SELECT * FROM squares JOIN numbers_v ON squares.a = numbers_v.a;
 $Q$);
  plan_is_distributed
 ---------------------------------------------------------------------
- f
+ t
 (1 row)
 
 BEGIN;
 SELECT * FROM squares JOIN numbers_v ON squares.a = numbers_v.a;
+NOTICE:  executing the command locally: SELECT squares.a, squares.b, numbers_v.a FROM (replicate_ref_to_coordinator.squares_8000000 squares JOIN replicate_ref_to_coordinator.numbers_v ON ((squares.a OPERATOR(pg_catalog.=) numbers_v.a)))
  a | b | a
 ---------------------------------------------------------------------
+ 1 | 1 | 1
  2 | 4 | 2
-(1 row)
+(2 rows)
 
 END;
 --
--- Joins between reference tables, local tables, and function calls shouldn't
+-- Joins between reference tables, local tables, and function calls
--- be planned locally.
+-- are allowed
 --
 SELECT count(*)
 FROM local_table a, numbers b, generate_series(1, 10) c
 WHERE a.a = b.a AND a.a = c;
-ERROR:  relation local_table is not distributed
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM replicate_ref_to_coordinator.local_table a, replicate_ref_to_coordinator.numbers_8000001 b, generate_series(1, 10) c(c) WHERE ((a.a OPERATOR(pg_catalog.=) b.a) AND (a.a OPERATOR(pg_catalog.=) c.c))
+ count
+---------------------------------------------------------------------
+     1
+(1 row)
+
 -- but it should be okay if the function call is not a data source
 SELECT public.plan_is_distributed($Q$
 EXPLAIN (COSTS FALSE)
@@ -362,7 +431,7 @@ SELECT abs(a.a) FROM local_table a, numbers b WHERE a.a = b.a;
 $Q$);
  plan_is_distributed
 ---------------------------------------------------------------------
- f
+ t
 (1 row)
 
 SELECT public.plan_is_distributed($Q$
@@ -371,7 +440,7 @@ SELECT a.a FROM local_table a, numbers b WHERE a.a = b.a ORDER BY abs(a.a);
 $Q$);
  plan_is_distributed
 ---------------------------------------------------------------------
- f
+ t
 (1 row)
 
 TRUNCATE local_table;
@@ -384,6 +453,7 @@ NOTICE:  executing the command locally: INSERT INTO replicate_ref_to_coordinator
 ALTER TABLE numbers ADD COLUMN d int;
 NOTICE:  executing the command locally: SELECT worker_apply_shard_ddl_command (8000001, 'replicate_ref_to_coordinator', 'ALTER TABLE numbers ADD COLUMN d int;')
 SELECT * FROM local_table JOIN numbers USING(a) ORDER BY a;
+NOTICE:  executing the command locally: SELECT local_table.a, numbers.d FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a, d) USING (a)) ORDER BY local_table.a
  a | d
 ---------------------------------------------------------------------
  1 |
@@ -397,6 +467,7 @@ BEGIN;
 INSERT INTO local_table VALUES (1), (2), (3);
 WITH t as (SELECT n.a, my_volatile_fn() x FROM numbers n NATURAL JOIN local_table l ORDER BY n.a, x)
 SELECT a FROM t NATURAL JOIN dist ORDER BY a;
+NOTICE:  executing the command locally: SELECT n.a, replicate_ref_to_coordinator.my_volatile_fn() AS x FROM (replicate_ref_to_coordinator.numbers_8000001 n(a) JOIN replicate_ref_to_coordinator.local_table l USING (a)) ORDER BY n.a, (replicate_ref_to_coordinator.my_volatile_fn())
  a
 ---------------------------------------------------------------------
 (0 rows)
@@ -409,6 +480,7 @@ NOTICE:  executing the copy locally for shard xxxxx
 INSERT INTO numbers SELECT * FROM numbers;
 NOTICE:  executing the command locally: INSERT INTO replicate_ref_to_coordinator.numbers_8000001 AS citus_table_alias (a) SELECT a FROM replicate_ref_to_coordinator.numbers_8000001 numbers
 SELECT COUNT(*) FROM local_table JOIN numbers using (a);
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a))
  count
 ---------------------------------------------------------------------
      6
@@ -417,6 +489,7 @@ SELECT COUNT(*) FROM local_table JOIN numbers using (a);
 UPDATE numbers SET a = a + 1;
 NOTICE:  executing the command locally: UPDATE replicate_ref_to_coordinator.numbers_8000001 numbers SET a = (a OPERATOR(pg_catalog.+) 1)
 SELECT COUNT(*) FROM local_table JOIN numbers using (a);
+NOTICE:  executing the command locally: SELECT count(*) AS count FROM (replicate_ref_to_coordinator.local_table JOIN replicate_ref_to_coordinator.numbers_8000001 numbers(a) USING (a))
  count
 ---------------------------------------------------------------------
      4

src/test/regress/expected/set_operation_and_local_tables.out

@@ -218,18 +218,20 @@ DEBUG:  Router planner cannot handle multi-shard select queries
 (2 rows)
 
 -- same query with subquery in where is wrapped in CTE
+SET citus.enable_cte_inlining TO off;
 SELECT * FROM test a WHERE x IN (WITH cte AS (SELECT x FROM test b UNION SELECT y FROM test c UNION SELECT y FROM local_test d) SELECT * FROM cte) ORDER BY 1,2;
-DEBUG:  CTE cte is going to be inlined via distributed planning
+DEBUG:  Local tables cannot be used in distributed queries.
+DEBUG:  generating subplan XXX_1 for CTE cte: SELECT b.x FROM recursive_set_local.test b UNION SELECT c.y FROM recursive_set_local.test c UNION SELECT d.y FROM recursive_set_local.local_test d
 DEBUG:  Local tables cannot be used in distributed queries.
 DEBUG:  generating subplan XXX_1 for subquery SELECT y FROM recursive_set_local.local_test d
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  generating subplan XXX_2 for subquery SELECT x FROM recursive_set_local.test b
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  generating subplan XXX_3 for subquery SELECT y FROM recursive_set_local.test c
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT intermediate_result.x FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer) UNION SELECT intermediate_result.y FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(y integer) UNION SELECT intermediate_result.y FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(y integer)
 DEBUG:  Creating router plan
 DEBUG:  Plan is router executable
-DEBUG:  generating subplan XXX_4 for subquery SELECT intermediate_result.x FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer) UNION SELECT intermediate_result.y FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(y integer) UNION SELECT intermediate_result.y FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(y integer)
+DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT x, y FROM recursive_set_local.test a WHERE (x OPERATOR(pg_catalog.=) ANY (SELECT cte.x FROM (SELECT intermediate_result.x FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(x integer)) cte)) ORDER BY x, y
-DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT x, y FROM recursive_set_local.test a WHERE (x OPERATOR(pg_catalog.=) ANY (SELECT cte.x FROM (SELECT intermediate_result.x FROM read_intermediate_result('XXX_4'::text, 'binary'::citus_copy_format) intermediate_result(x integer)) cte)) ORDER BY x, y
 DEBUG:  Router planner cannot handle multi-shard select queries
  x | y
 ---------------------------------------------------------------------
@@ -237,7 +239,8 @@ DEBUG:  Router planner cannot handle multi-shard select queries
  2 | 2
 (2 rows)
 
--- not supported since local table is joined with a set operation
+RESET citus.enable_cte_inlining;
+-- supported since final step only has local table and intermediate result
 SELECT * FROM ((SELECT * FROM test) EXCEPT (SELECT * FROM test ORDER BY x LIMIT 1)) u JOIN local_test USING (x) ORDER BY 1,2;
 DEBUG:  Local tables cannot be used in distributed queries.
 DEBUG:  Router planner cannot handle multi-shard select queries
@@ -249,8 +252,12 @@ DEBUG:  Creating router plan
 DEBUG:  Plan is router executable
 DEBUG:  generating subplan XXX_3 for subquery SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer) EXCEPT SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)
 DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT u.x, u.y, local_test.y FROM ((SELECT intermediate_result.x, intermediate_result.y FROM read_intermediate_result('XXX_3'::text, 'binary'::citus_copy_format) intermediate_result(x integer, y integer)) u JOIN recursive_set_local.local_test USING (x)) ORDER BY u.x, u.y
-DEBUG:  Local tables cannot be used in distributed queries.
+DEBUG:  Creating router plan
-ERROR:  relation local_test is not distributed
+DEBUG:  Plan is router executable
+ x | y | y
+---------------------------------------------------------------------
+(0 rows)
+
 -- though we replace some queries including the local query, the intermediate result is on the outer part of an outer join
 SELECT * FROM ((SELECT * FROM local_test) INTERSECT (SELECT * FROM test ORDER BY x LIMIT 1)) u LEFT JOIN test USING (x) ORDER BY 1,2;
 DEBUG:  Local tables cannot be used in distributed queries.

src/test/regress/expected/with_executors.out

@@ -4,6 +4,14 @@ SET search_path TO with_executors, public;
 SET citus.enable_repartition_joins TO on;
 CREATE TABLE with_executors.local_table (id int);
 INSERT INTO local_table VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
+CREATE TABLE ref_table (id int);
+SELECT create_reference_table('ref_table');
+ create_reference_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO ref_table VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
 -- CTEs should be able to use local queries
 WITH cte AS (
 	WITH local_cte AS (
@@ -284,11 +292,39 @@ SELECT DISTINCT uid_1, val_3 FROM cte join events_table on cte.val_3=events_tabl
      2 |     1
 (1 row)
 
--- CTEs should not be able to terminate (the last SELECT) in a local query
+-- CTEs should be able to terminate (the last SELECT) in a local query
 WITH cte AS (
-	SELECT * FROM users_table
+	SELECT user_id FROM users_table
 )
-SELECT count(*) FROM cte JOIN local_table ON (user_id = id);
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id);
+ min
+---------------------------------------------------------------------
+   1
+(1 row)
+
+-- not if there are no distributed tables
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id) JOIN events_table USING (user_id);
+ERROR:  relation local_table is not distributed
+-- unless the distributed table is part of a recursively planned subquery
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id) JOIN (SELECT * FROM events_table OFFSET 0) e USING (user_id);
+ min
+---------------------------------------------------------------------
+   1
+(1 row)
+
+-- joins between local and reference tables not allowed
+-- since the coordinator is not in the metadata at this stage
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT count(*) FROM local_table JOIN ref_table USING (id)
+WHERE id IN (SELECT * FROM cte);
 ERROR:  relation local_table is not distributed
 -- CTEs should be able to terminate a router query
 WITH cte AS (
@@ -382,4 +418,6 @@ WHERE
 	users_table.user_id = cte_merge.u_id;
 ERROR:  Complex subqueries and CTEs are not supported when task_executor_type is set to 'task-tracker'
 DROP SCHEMA with_executors CASCADE;
-NOTICE:  drop cascades to table local_table
+NOTICE:  drop cascades to 2 other objects
+DETAIL:  drop cascades to table local_table
+drop cascades to table ref_table

src/test/regress/sql/coordinator_shouldhaveshards.sql

@@ -155,6 +155,24 @@ SELECT * FROM ref JOIN local ON (a = x);
 -- in postgres we wouldn't see this modifying cte, so it is consistent with postgres.
 WITH a AS (SELECT count(*) FROM test), b AS (INSERT INTO local VALUES (3,2) RETURNING *), c AS (INSERT INTO ref VALUES (3,2) RETURNING *), d AS (SELECT count(*) FROM ref JOIN local ON (a = x)) SELECT * FROM a, b, c, d ORDER BY x,y,a,b;
 
+-- joins between local tables and distributed tables are disallowed
+CREATE TABLE dist_table(a int);
+SELECT create_distributed_table('dist_table', 'a');
+INSERT INTO dist_table VALUES(1);
+
+SELECT * FROM local JOIN dist_table ON (a = x);
+SELECT * FROM local JOIN dist_table ON (a = x) WHERE a = 1;;
+
+-- intermediate results are allowed
+WITH cte_1 AS (SELECT * FROM dist_table LIMIT 1)
+SELECT * FROM ref JOIN local ON (a = x) JOIN cte_1 ON (local.x = cte_1.a);
+
+-- full router query with CTE and local
+WITH cte_1 AS (SELECT * FROM ref LIMIT 1)
+SELECT * FROM ref JOIN local ON (a = x) JOIN cte_1 ON (local.x = cte_1.a);
+
+DROP TABLE dist_table;
+
 -- issue #3801
 SET citus.shard_replication_factor TO 2;
 CREATE TABLE dist_table(a int);

src/test/regress/sql/locally_execute_intermediate_results.sql

@@ -2,7 +2,6 @@ CREATE SCHEMA locally_execute_intermediate_results;
 SET search_path TO locally_execute_intermediate_results;
 SET citus.log_intermediate_results TO TRUE;
 SET citus.log_local_commands TO TRUE;
-SET client_min_messages TO DEBUG1;
 
 SET citus.shard_count TO 4;
 SET citus.next_shard_id TO 1580000;
@@ -18,16 +17,21 @@ SELECT create_distributed_table('table_2', 'key');
 CREATE TABLE ref_table (key int, value text);
 SELECT create_reference_table('ref_table');
 
+CREATE TABLE local_table (key int, value text);
+
 -- load some data
 INSERT INTO table_1    VALUES (1, '1'), (2, '2'), (3, '3'), (4, '4');
 INSERT INTO table_2    VALUES                     (3, '3'), (4, '4'), (5, '5'), (6, '6');
 INSERT INTO ref_table  VALUES (1, '1'), (2, '2'), (3, '3'), (4, '4'), (5, '5'), (6, '6');
+INSERT INTO local_table VALUES                    (3, '3'), (4, '4'), (5, '5'), (6, '6');
 
 -- prevent PG 11 - PG 12 outputs to diverge
 -- and have a lot more CTEs recursively planned for the
 -- sake of increasing the test coverage
 SET citus.enable_cte_inlining TO false;
 
+SET client_min_messages TO DEBUG1;
+
 -- the query cannot be executed locally, but still because of
 -- HAVING the intermediate result is written to local file as well
 WITH cte_1 AS (SELECT max(value) FROM table_1)
@@ -233,6 +237,26 @@ SELECT * FROM
   (SELECT key FROM table_2 GROUP BY key HAVING max(value) > (SELECT * FROM cte_2) LIMIT 1) as bar
   WHERE foo.key != bar.key;
 
+-- queries in which the last step has only CTEs can use local tables
+WITH cte_1 AS (SELECT max(value) FROM table_1)
+SELECT
+count(*)
+FROM
+local_table
+GROUP BY key
+HAVING max(value) > (SELECT max FROM cte_1);
+
+WITH cte_1 AS (SELECT max(value) FROM table_1),
+cte_2 AS (SELECT * FROM table_2)
+SELECT
+count(*)
+FROM
+local_table
+WHERE
+key > (SELECT key FROM cte_2 ORDER BY 1 LIMIT 1)
+GROUP BY key
+HAVING max(value) > (SELECT max FROM cte_1);
+
 \c - - - :worker_1_port
 
 -- now use the same queries on a worker

src/test/regress/sql/multi_modifications.sql

@@ -874,7 +874,7 @@ DELETE FROM summary_table WHERE (
     SELECT 1 FROM pg_catalog.pg_statio_sys_sequences
 ) = null;
 DELETE FROM summary_table WHERE (
-    SELECT (select action_statement from information_schema.triggers)
+    SELECT (select min(action_statement) from information_schema.triggers)
     FROM pg_catalog.pg_statio_sys_sequences
 ) = null;
 

src/test/regress/sql/multi_mx_add_coordinator.sql

@@ -63,7 +63,7 @@ INSERT INTO ref VALUES (1), (2), (3);
 UPDATE ref SET a = a + 1;
 DELETE FROM ref WHERE a > 3;
 
--- Test we don't allow reference/local joins on mx workers
+-- Test we allow reference/local joins on mx workers
 CREATE TABLE local_table (a int);
 INSERT INTO local_table VALUES (2), (4);
 

src/test/regress/sql/replicate_reference_tables_to_coordinator.sql

@@ -51,7 +51,7 @@ SELECT citus_table_is_visible('numbers_8000001'::regclass::oid);
 CREATE TABLE local_table(a int);
 INSERT INTO local_table VALUES (2), (4), (7), (20);
 
-EXPLAIN SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers;
+EXPLAIN (COSTS OFF) SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers;
 SELECT local_table.a, numbers.a FROM local_table NATURAL JOIN numbers ORDER BY 1;
 
 -- test non equijoin
@@ -135,7 +135,7 @@ $$ LANGUAGE sql;
 
 SELECT test_reference_local_join_func();
 
--- shouldn't plan locally if modifications happen in CTEs, ...
+-- CTEs are allowed
 WITH ins AS (INSERT INTO numbers VALUES (1) RETURNING *)
 SELECT * FROM numbers, local_table;
 
@@ -143,7 +143,6 @@ WITH t AS (SELECT *, my_volatile_fn() x FROM numbers FOR UPDATE)
 SELECT * FROM numbers, local_table
 WHERE EXISTS (SELECT * FROM t WHERE t.x = numbers.a);
 
--- but this should be fine
 WITH t AS (SELECT *, my_volatile_fn() x FROM numbers)
 SELECT * FROM numbers, local_table
 WHERE EXISTS (SELECT * FROM t WHERE t.x = numbers.a);
@@ -200,8 +199,8 @@ SELECT * FROM squares JOIN numbers_v ON squares.a = numbers_v.a;
 END;
 
 --
--- Joins between reference tables, local tables, and function calls shouldn't
+-- Joins between reference tables, local tables, and function calls
--- be planned locally.
+-- are allowed
 --
 SELECT count(*)
 FROM local_table a, numbers b, generate_series(1, 10) c

src/test/regress/sql/set_operation_and_local_tables.sql

@@ -74,9 +74,11 @@ FROM
 SELECT * FROM test a WHERE x IN (SELECT x FROM test b UNION SELECT y FROM test c UNION SELECT y FROM local_test d) ORDER BY 1,2;
 
 -- same query with subquery in where is wrapped in CTE
+SET citus.enable_cte_inlining TO off;
 SELECT * FROM test a WHERE x IN (WITH cte AS (SELECT x FROM test b UNION SELECT y FROM test c UNION SELECT y FROM local_test d) SELECT * FROM cte) ORDER BY 1,2;
+RESET citus.enable_cte_inlining;
 
--- not supported since local table is joined with a set operation
+-- supported since final step only has local table and intermediate result
 SELECT * FROM ((SELECT * FROM test) EXCEPT (SELECT * FROM test ORDER BY x LIMIT 1)) u JOIN local_test USING (x) ORDER BY 1,2;
 
 -- though we replace some queries including the local query, the intermediate result is on the outer part of an outer join

src/test/regress/sql/with_executors.sql

@@ -7,6 +7,10 @@ SET citus.enable_repartition_joins TO on;
 CREATE TABLE with_executors.local_table (id int);
 INSERT INTO local_table VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
 
+CREATE TABLE ref_table (id int);
+SELECT create_reference_table('ref_table');
+INSERT INTO ref_table VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9), (10);
+
 -- CTEs should be able to use local queries
 WITH cte AS (
 	WITH local_cte AS (
@@ -221,11 +225,31 @@ WITH cte AS (
 SELECT DISTINCT uid_1, val_3 FROM cte join events_table on cte.val_3=events_table.event_type ORDER BY 1, 2;
 
 
--- CTEs should not be able to terminate (the last SELECT) in a local query
+-- CTEs should be able to terminate (the last SELECT) in a local query
 WITH cte AS (
-	SELECT * FROM users_table
+	SELECT user_id FROM users_table
 )
-SELECT count(*) FROM cte JOIN local_table ON (user_id = id);
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id);
+
+-- not if there are no distributed tables
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id) JOIN events_table USING (user_id);
+
+-- unless the distributed table is part of a recursively planned subquery
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT min(user_id) FROM cte JOIN local_table ON (user_id = id) JOIN (SELECT * FROM events_table OFFSET 0) e USING (user_id);
+
+-- joins between local and reference tables not allowed
+-- since the coordinator is not in the metadata at this stage
+WITH cte AS (
+	SELECT user_id FROM users_table
+)
+SELECT count(*) FROM local_table JOIN ref_table USING (id)
+WHERE id IN (SELECT * FROM cte);
 
 -- CTEs should be able to terminate a router query
 WITH cte AS (