Hi, I took a look into the hasModifyingCTE bugfix recently, and found a possible bug case without the parallel insert patch.
--------------------------------- drop table if exists test_data1; create table test_data1(a int, b int) ; insert into test_data1 select generate_series(1,1000), generate_series(1,1000); set force_parallel_mode=on; CREATE TEMP TABLE bug6051 AS select i from generate_series(1,3) as i; SELECT * FROM bug6051; CREATE RULE bug6051_ins AS ON INSERT TO bug6051 DO INSTEAD select a as i from test_data1; WITH t1 AS ( DELETE FROM bug6051 RETURNING * ) INSERT INTO bug6051 SELECT * FROM t1; ******* ***ERROR: cannot assign XIDs during a parallel operation ******* --------------------------------- I debugged it and it did have modifycte in the parsetree after rewrite. I think if we can properly set the hasModifyingCTE, we can avoid this error by not consider parallel for this. Thoughts ? Best regards, houzj