On Wed, Apr 8, 2026 at 11:00 PM Alexander Korotkov <aekorotkov@gmail.com> wrote:
Hi, Satya!
On Thu, Apr 9, 2026 at 5:03 AM SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com> wrote: > An assertion failure (server crash in assert-enabled builds) occurs when WAIT FOR LSN ... INTO is used inside PL/pgSQL DO blocks or within void procedures. > > Repro: > > -- Run this on a standby > > CREATE PROCEDURE test_wait() > LANGUAGE plpgsql AS $$ > DECLARE > result text; > BEGIN > WAIT FOR LSN '0/1234' INTO result; > RAISE NOTICE '%', result; > END; > $$; > CALL test_wait(); > > > The WAIT FOR itself succeeds, but the very next PL/pgSQL statement that requires a snapshot crashes the backend with: > > TRAP: failed Assert("portal->portalSnapshot == NULL"), > File: "pquery.c", Line: 1776 > > Attached patches for both the test case and a potential fix. Please review.
Thank you for reporting. But I doubt the fix is correct. Even that this particular might work OK, I don't think it's safe to release snapshots belonging to functions/procedures: it might affect them. I tend to think we must forbid wrapping WAIT FOR LSN with functions/procedures. I'll explore more on this today.
Agreed, attached a v2 patch with your suggestion on preventing it running
