Improve error message for recursive CTEs (#7407)

Fixes #2870

src/backend/distributed/planner/recursive_planning.c

@@ -1097,8 +1097,8 @@ RecursivelyPlanCTEs(Query *query, RecursivePlanningContext *planningContext)
 	if (query->hasRecursive)
 	{
 		return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
-							 "recursive CTEs are not supported in distributed "
-							 "queries",
+							 "recursive CTEs are only supported when they "
+							 "contain a filter on the distribution column",
 							 NULL, NULL);
 	}
 

src/test/regress/expected/multi_mx_router_planner.out

@@ -370,7 +370,7 @@ WITH RECURSIVE hierarchy as (
 				h.company_id = ce.company_id))
 SELECT * FROM hierarchy WHERE LEVEL <= 2;
 DEBUG:  Router planner cannot handle multi-shard select queries
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- logically wrong query, query involves different shards
 -- from the same table, but still router plannable due to
 -- shard being placed on the same worker.
@@ -386,7 +386,7 @@ WITH RECURSIVE hierarchy as (
 				ce.company_id = 2))
 SELECT * FROM hierarchy WHERE LEVEL <= 2;
 DEBUG:  router planner does not support queries that reference non-colocated distributed tables
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- grouping sets are supported on single shard
 SELECT
 	id, substring(title, 2, 1) AS subtitle, count(*)

src/test/regress/expected/multi_router_planner.out

@@ -436,7 +436,7 @@ WITH RECURSIVE hierarchy as MATERIALIZED (
 				h.company_id = ce.company_id))
 SELECT * FROM hierarchy WHERE LEVEL <= 2;
 DEBUG:  Router planner cannot handle multi-shard select queries
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- logically wrong query, query involves different shards
 -- from the same table
 WITH RECURSIVE hierarchy as MATERIALIZED (
@@ -451,7 +451,7 @@ WITH RECURSIVE hierarchy as MATERIALIZED (
 				ce.company_id = 2))
 SELECT * FROM hierarchy WHERE LEVEL <= 2;
 DEBUG:  router planner does not support queries that reference non-colocated distributed tables
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- Test router modifying CTEs
 WITH new_article AS MATERIALIZED(
     INSERT INTO articles_hash VALUES (1,  1, 'arsenous', 9) RETURNING *

src/test/regress/expected/pg14.out

@@ -1142,7 +1142,7 @@ WITH RECURSIVE search_graph(f, t, label) AS (
         WHERE g.f = sg.t and  g.f = 1
 ) SEARCH DEPTH FIRST BY f, t SET seq
 SELECT * FROM search_graph ORDER BY seq;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 WITH RECURSIVE search_graph(f, t, label) AS (
     SELECT * FROM graph0 g WHERE f = 1
     UNION ALL
@@ -1151,7 +1151,7 @@ WITH RECURSIVE search_graph(f, t, label) AS (
         WHERE g.f = sg.t and  g.f = 1
 ) SEARCH DEPTH FIRST BY f, t SET seq
 DELETE FROM graph0 WHERE t IN (SELECT t FROM search_graph ORDER BY seq);
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 CREATE TABLE graph1(f INT, t INT, label TEXT);
 SELECT create_reference_table('graph1');
  create_reference_table
@@ -1170,7 +1170,7 @@ WITH RECURSIVE search_graph(f, t, label) AS (
         WHERE g.f = sg.t and  g.f = 1
 ) SEARCH DEPTH FIRST BY f, t SET seq
 SELECT * FROM search_graph ORDER BY seq;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 WITH RECURSIVE search_graph(f, t, label) AS (
     SELECT * FROM graph1 g WHERE f = 1
     UNION ALL
@@ -1179,7 +1179,7 @@ WITH RECURSIVE search_graph(f, t, label) AS (
         WHERE g.f = sg.t and  g.f = 1
 ) SEARCH DEPTH FIRST BY f, t SET seq
 DELETE FROM graph1 WHERE t IN (SELECT t FROM search_graph ORDER BY seq);
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 SELECT * FROM (
     WITH RECURSIVE search_graph(f, t, label) AS (
         SELECT *
@@ -1191,7 +1191,7 @@ SELECT * FROM (
     ) SEARCH DEPTH FIRST BY f, t SET seq
     SELECT * FROM search_graph ORDER BY seq
 ) as foo;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 --
 -- https://github.com/citusdata/citus/issues/5258
 --

src/test/regress/expected/query_single_shard_table.out

@@ -1529,7 +1529,7 @@ DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  Router planner cannot handle multi-shard select queries
 DEBUG:  generating subplan XXX_1 for CTE level_1: WITH RECURSIVE level_2_recursive(x) AS (VALUES (1) UNION ALL SELECT (nullkey_c1_t1.a OPERATOR(pg_catalog.+) 1) FROM (query_single_shard_table.nullkey_c1_t1 JOIN level_2_recursive level_2_recursive_1 ON ((nullkey_c1_t1.a OPERATOR(pg_catalog.=) level_2_recursive_1.x))) WHERE (nullkey_c1_t1.a OPERATOR(pg_catalog.<) 100)) SELECT level_2_recursive.x, distributed_table.a, distributed_table.b FROM (level_2_recursive JOIN query_single_shard_table.distributed_table ON ((level_2_recursive.x OPERATOR(pg_catalog.=) distributed_table.a)))
 DEBUG:  Router planner cannot handle multi-shard select queries
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- grouping set
 SELECT
 	id, substring(title, 2, 1) AS subtitle, count(*)

src/test/regress/expected/subquery_and_cte.out

@@ -527,7 +527,7 @@ FROM
      ) as bar
 WHERE foo.user_id = bar.user_id
 ORDER BY 1 DESC;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 CREATE TABLE ref_table_1 (a int);
 SELECT create_reference_table('ref_table_1');
  create_reference_table

src/test/regress/expected/with_basics.out

@@ -664,14 +664,14 @@ WITH RECURSIVE basic_recursive(x) AS (
     SELECT user_id + 1 FROM users_table JOIN basic_recursive ON (user_id = x) WHERE user_id < 100
 )
 SELECT sum(x) FROM basic_recursive;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 WITH RECURSIVE basic_recursive AS (
     SELECT -1 as user_id, '2017-11-22 20:16:16.614779'::timestamp, -1, -1, -1, -1
   UNION ALL
     SELECT basic_recursive.* FROM users_table JOIN basic_recursive USING (user_id) WHERE user_id>1
 )
 SELECT * FROM basic_recursive ORDER BY user_id LIMIT 1;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- basic_recursive in FROM should error out
 SELECT
   *
@@ -682,7 +682,7 @@ FROM
       SELECT basic_recursive.* FROM users_table JOIN basic_recursive USING (user_id) WHERE user_id>1
   )
   SELECT * FROM basic_recursive ORDER BY user_id LIMIT 1) cte_rec;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- basic_recursive in WHERE with UNION ALL
 SELECT
   *
@@ -696,7 +696,7 @@ WHERE
       SELECT basic_recursive.* FROM users_table JOIN basic_recursive USING (user_id) WHERE user_id>1
   )
   SELECT * FROM basic_recursive ORDER BY user_id LIMIT 1);
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- one recursive one regular CTE should error out
 WITH RECURSIVE basic_recursive(x) AS(
     VALUES (1)
@@ -707,7 +707,7 @@ basic AS (
     SELECT count(user_id) FROM users_table
 )
 SELECT x FROM basic, basic_recursive;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- one recursive one regular which SELECTs from the recursive CTE under a simple SELECT
 WITH RECURSIVE basic_recursive(x) AS(
     VALUES (1)
@@ -718,7 +718,7 @@ basic AS (
     SELECT count(x) FROM basic_recursive
 )
 SELECT * FROM basic;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- recursive CTE in a NESTED manner
 WITH regular_cte AS (
   WITH regular_2 AS (
@@ -732,7 +732,7 @@ WITH regular_cte AS (
   SELECT * FROM regular_2
 )
 SELECT * FROM regular_cte;
-ERROR:  recursive CTEs are not supported in distributed queries
+ERROR:  recursive CTEs are only supported when they contain a filter on the distribution column
 -- CTEs should work with VIEWs as well
 CREATE VIEW basic_view AS
 SELECT * FROM users_table;