address feedback from Sait Talha & Hadi

src/backend/distributed/planner/multi_physical_planner.c

@@ -2646,8 +2646,8 @@ QueryPushdownTaskCreate(Query *originalQuery, int shardIndex,
 
 	Assert(anchorShardId != INVALID_SHARD_ID);
 
-	List *selectPlacementList = PlacementsForWorkersContainingAllShards(taskShardList);
+	List *taskPlacementList = PlacementsForWorkersContainingAllShards(taskShardList);
-	if (list_length(selectPlacementList) == 0)
+	if (list_length(taskPlacementList) == 0)
 	{
 		ereport(ERROR, (errmsg("cannot find a worker that has active placements for all "
 							   "shards in the query")));
@@ -2683,7 +2683,7 @@ QueryPushdownTaskCreate(Query *originalQuery, int shardIndex,
 
 	subqueryTask->dependentTaskList = NULL;
 	subqueryTask->anchorShardId = anchorShardId;
-	subqueryTask->taskPlacementList = selectPlacementList;
+	subqueryTask->taskPlacementList = taskPlacementList;
 	subqueryTask->relationShardList = relationShardList;
 
 	return subqueryTask;

src/backend/distributed/planner/multi_router_planner.c

@@ -2179,7 +2179,7 @@ PlanRouterQuery(Query *originalQuery,
  * accessed locally.
  *
  * If generateDummyPlacement is true and there are no shards that need to be
- * accessed to answer the query (shardsPresent is false), then as single
+ * accessed to answer the query (shardsPresent is false), then a single
  * placement is returned that is either local or follows a round-robin policy.
  * A typical example is a router query that only reads an intermediate result.
  * This will happen on the coordinator, unless the user wants to balance the
@@ -3296,7 +3296,7 @@ MultiRouterPlannableQuery(Query *query)
 		}
 	}
 
-	/* local tables are allowed if there are no distributed tables */
+	/* local tables are not allowed if there are distributed tables */
 	if (hasLocalTable && hasDistributedTable)
 	{
 		return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,

src/test/regress/expected/multi_test_helpers.out

@@ -29,20 +29,6 @@ BEGIN
   END LOOP;
   RETURN;
 END; $$ language plpgsql;
--- Is a distributed plan?
-CREATE OR REPLACE FUNCTION plan_is_distributed(explain_commmand text)
-RETURNS BOOLEAN AS $$
-DECLARE
-    query_plan TEXT;
-BEGIN
-  FOR query_plan IN execute explain_commmand LOOP
-    IF query_plan LIKE '%Task Count:%'
-    THEN
-        RETURN TRUE;
-    END IF;
-  END LOOP;
-  RETURN FALSE;
-END; $$ language plpgsql;
 -- helper function to quickly run SQL on the whole cluster
 CREATE OR REPLACE FUNCTION run_command_on_coordinator_and_workers(p_sql text)
 RETURNS void LANGUAGE plpgsql AS $$

src/test/regress/expected/replicate_reference_tables_to_coordinator.out

@@ -386,22 +386,12 @@ $Q$);
 DROP VIEW numbers_v, local_table_v;
 --
 -- Joins between reference tables and materialized views are allowed to
--- be planned locally.
+-- be planned to be executed locally.
 --
 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
----------------------------------------------------------------------
- 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
@@ -410,7 +400,6 @@ NOTICE:  executing the command locally: SELECT squares.a, squares.b, numbers_v.a
  2 | 4 | 2
 (2 rows)
 
-END;
 --
 -- Joins between reference tables, local tables, and function calls
 -- are allowed
@@ -424,24 +413,22 @@ NOTICE:  executing the command locally: SELECT count(*) AS count FROM replicate_
      1
 (1 row)
 
--- but it should be okay if the function call is not a data source
+-- and it should be okay if the function call is not a data source
-SELECT public.plan_is_distributed($Q$
-EXPLAIN (COSTS FALSE)
 SELECT abs(a.a) FROM local_table a, numbers b WHERE a.a = b.a;
-$Q$);
+NOTICE:  executing the command locally: SELECT abs(a.a) AS abs FROM replicate_ref_to_coordinator.local_table a, replicate_ref_to_coordinator.numbers_8000001 b WHERE (a.a OPERATOR(pg_catalog.=) b.a)
- plan_is_distributed
+ abs
 ---------------------------------------------------------------------
- t
+   2
-(1 row)
+  20
+(2 rows)
 
-SELECT public.plan_is_distributed($Q$
-EXPLAIN (COSTS FALSE)
 SELECT a.a FROM local_table a, numbers b WHERE a.a = b.a ORDER BY abs(a.a);
-$Q$);
+NOTICE:  executing the command locally: SELECT a.a FROM replicate_ref_to_coordinator.local_table a, replicate_ref_to_coordinator.numbers_8000001 b WHERE (a.a OPERATOR(pg_catalog.=) b.a) ORDER BY (abs(a.a))
- plan_is_distributed
+ a
 ---------------------------------------------------------------------
- t
+  2
-(1 row)
+ 20
+(2 rows)
 
 TRUNCATE local_table;
 TRUNCATE numbers;

src/test/regress/sql/multi_test_helpers.sql

@@ -33,21 +33,6 @@ BEGIN
   RETURN;
 END; $$ language plpgsql;
 
--- Is a distributed plan?
-CREATE OR REPLACE FUNCTION plan_is_distributed(explain_commmand text)
-RETURNS BOOLEAN AS $$
-DECLARE
-    query_plan TEXT;
-BEGIN
-  FOR query_plan IN execute explain_commmand LOOP
-    IF query_plan LIKE '%Task Count:%'
-    THEN
-        RETURN TRUE;
-    END IF;
-  END LOOP;
-  RETURN FALSE;
-END; $$ language plpgsql;
-
 -- helper function to quickly run SQL on the whole cluster
 CREATE OR REPLACE FUNCTION run_command_on_coordinator_and_workers(p_sql text)
 RETURNS void LANGUAGE plpgsql AS $$

src/test/regress/sql/replicate_reference_tables_to_coordinator.sql

@@ -185,18 +185,12 @@ DROP VIEW numbers_v, local_table_v;
 
 --
 -- Joins between reference tables and materialized views are allowed to
--- be planned locally.
+-- be planned to be executed locally.
 --
 CREATE MATERIALIZED VIEW numbers_v AS SELECT * FROM numbers WHERE a BETWEEN 1 AND 10;
 REFRESH MATERIALIZED VIEW numbers_v;
-SELECT public.plan_is_distributed($Q$
-EXPLAIN (COSTS FALSE)
-	SELECT * FROM squares JOIN numbers_v ON squares.a = numbers_v.a;
-$Q$);
 
-BEGIN;
 SELECT * FROM squares JOIN numbers_v ON squares.a = numbers_v.a;
-END;
 
 --
 -- Joins between reference tables, local tables, and function calls
@@ -206,16 +200,10 @@ SELECT count(*)
 FROM local_table a, numbers b, generate_series(1, 10) c
 WHERE a.a = b.a AND a.a = c;
 
--- but it should be okay if the function call is not a data source
+-- and it should be okay if the function call is not a data source
-SELECT public.plan_is_distributed($Q$
-EXPLAIN (COSTS FALSE)
 SELECT abs(a.a) FROM local_table a, numbers b WHERE a.a = b.a;
-$Q$);
 
-SELECT public.plan_is_distributed($Q$
-EXPLAIN (COSTS FALSE)
 SELECT a.a FROM local_table a, numbers b WHERE a.a = b.a ORDER BY abs(a.a);
-$Q$);
 
 TRUNCATE local_table;
 TRUNCATE numbers;