postgres
diff --git a/‎src/backend/rewrite/rewriteHandler.c
Copy file name to clipboardExpand all lines: src/backend/rewrite/rewriteHandler.c
+6Lines changed: 6 additions & 0 deletions b/‎src/backend/rewrite/rewriteHandler.c
Copy file name to clipboardExpand all lines: src/backend/rewrite/rewriteHandler.c
+6Lines changed: 6 additions & 0 deletions
diff --git a/‎src/test/regress/expected/with.out
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+27Lines changed: 27 additions & 0 deletions b/‎src/test/regress/expected/with.out
Copy file name to clipboardExpand all lines: src/test/regress/expected/with.out
+27Lines changed: 27 additions & 0 deletions
diff --git a/‎src/test/regress/sql/with.sql
Copy file name to clipboardExpand all lines: src/test/regress/sql/with.sql
+16Lines changed: 16 additions & 0 deletions b/‎src/test/regress/sql/with.sql
Copy file name to clipboardExpand all lines: src/test/regress/sql/with.sql
+16Lines changed: 16 additions & 0 deletions
@@ -536,6 +536,9 @@ 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)
 		{
@@ -557,6 +560,9 @@ 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;
 	}
 
 	/*
 
@@ -2277,6 +2277,33 @@ 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
 
@@ -1070,6 +1070,22 @@ 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