Revert "Propagate CTE property flags when copying a CTE list into a rule."

tglsfdc · tglsfdc · commit f94924f01e48 · 2021-02-07T12:54:08.000-05:00
This reverts commit ed29089 and equivalent back-branch commits. The issue is subtler than I thought, and it's far from new, so just before a release deadline is no time to be fooling with it. We'll consider what to do at a bit more leisure. Discussion: https://postgr.es/m/CAJcOf-fAdj=nDKMsRhQzndm-O13NY4dL6xGcEvdX5Xvbbi0V7g@mail.gmail.com
diff --git a/src/backend/rewrite/rewriteHandler.c b/src/backend/rewrite/rewriteHandler.c
@@ -525,9 +525,6 @@ rewriteRuleAction(Query *parsetree,
 		 *
 		 * This could possibly be fixed by using some sort of internally
 		 * generated ID, instead of names, to link CTE RTEs to their CTEs.
-		 * However, decompiling the results would be quite confusing; note the
-		 * merge of hasRecursive flags below, which could change the apparent
-		 * semantics of such redundantly-named CTEs.
 		 */
 		foreach(lc, parsetree->cteList)
 		{
@@ -549,9 +546,6 @@ rewriteRuleAction(Query *parsetree,
 		/* OK, it's safe to combine the CTE lists */
 		sub_action->cteList = list_concat(sub_action->cteList,
 										  copyObject(parsetree->cteList));
-		/* ... and don't forget about the associated flags */
-		sub_action->hasRecursive |= parsetree->hasRecursive;
-		sub_action->hasModifyingCTE |= parsetree->hasModifyingCTE;
 	}
 
 	/*
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
@@ -1672,33 +1672,6 @@ SELECT * FROM bug6051_2;
  3
 (3 rows)
 
--- silly example to verify that hasModifyingCTE flag is propagated
-CREATE TEMP TABLE bug6051_3 AS
-  select a from generate_series(11,13) as a;
-CREATE RULE bug6051_3_ins AS ON INSERT TO bug6051_3 DO INSTEAD
-  SELECT i FROM bug6051_2;
-BEGIN; SET LOCAL force_parallel_mode = on;
-WITH t1 AS ( DELETE FROM bug6051_3 RETURNING * )
-  INSERT INTO bug6051_3 SELECT * FROM t1;
- i 
----
- 1
- 2
- 3
- 1
- 2
- 3
- 1
- 2
- 3
-(9 rows)
-
-COMMIT;
-SELECT * FROM bug6051_3;
- a 
----
-(0 rows)
-
 -- a truly recursive CTE in the same list
 WITH RECURSIVE t(a) AS (
 	SELECT 0
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
@@ -773,22 +773,6 @@ INSERT INTO bug6051 SELECT * FROM t1;
 SELECT * FROM bug6051;
 SELECT * FROM bug6051_2;
 
--- silly example to verify that hasModifyingCTE flag is propagated
-CREATE TEMP TABLE bug6051_3 AS
-  select a from generate_series(11,13) as a;
-
-CREATE RULE bug6051_3_ins AS ON INSERT TO bug6051_3 DO INSTEAD
-  SELECT i FROM bug6051_2;
-
-BEGIN; SET LOCAL force_parallel_mode = on;
-
-WITH t1 AS ( DELETE FROM bug6051_3 RETURNING * )
-  INSERT INTO bug6051_3 SELECT * FROM t1;
-
-COMMIT;
-
-SELECT * FROM bug6051_3;
-
 -- a truly recursive CTE in the same list
 WITH RECURSIVE t(a) AS (
 	SELECT 0

Original file line number	Diff line number	Diff line change
`@@ -525,9 +525,6 @@ rewriteRuleAction(Query *parsetree,`
`525`	`525`	`*`
`526`	`526`	`* This could possibly be fixed by using some sort of internally`
`527`	`527`	`* generated ID, instead of names, to link CTE RTEs to their CTEs.`
`528`		`- * However, decompiling the results would be quite confusing; note the`
`529`		`- * merge of hasRecursive flags below, which could change the apparent`
`530`		`- * semantics of such redundantly-named CTEs.`
`531`	`528`	`*/`
`532`	`529`	`foreach(lc, parsetree->cteList)`
`533`	`530`	`{`
`@@ -549,9 +546,6 @@ rewriteRuleAction(Query *parsetree,`
`549`	`546`	`/* OK, it's safe to combine the CTE lists */`
`550`	`547`	`sub_action->cteList = list_concat(sub_action->cteList,`
`551`	`548`	`copyObject(parsetree->cteList));`
`552`		`- /* ... and don't forget about the associated flags */`
`553`		`- sub_action->hasRecursive \|= parsetree->hasRecursive;`
`554`		`- sub_action->hasModifyingCTE \|= parsetree->hasModifyingCTE;`
`555`	`549`	`}`
`556`	`550`
`557`	`551`	`/*`