Hi hackers, Alexander,
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.
Thanks,
Satya
