Re: IPC/MultixactCreation on the Standby server

On 28.07.2025 15:49, Andrey Borodin wrote:
> I also attach a version for PG17, maybe Dmitry could try to reproduce the problem with this patch.

Andrey, thank you very much for your work, and also thanks to Álvaro for
joining the discussion on the problem. I ran tests on PG17 with patch
v8, there are no more sessions hanging on the replica, great! Replica
requests are canceled with recovery conflicts. ERROR: canceling
statement due to conflict with recovery DETAIL: User was holding shared
buffer pin for too long. STATEMENT: select sum(val) from tbl2; or ERROR:
canceling statement due to conflict with recovery DETAIL: User query
might have needed to see row versions that must be removed. STATEMENT:
select sum(val) from tbl2;

But on the master, some of the requests then fail with an error,
apparently invalid multixact's remain in the pages. ERROR: MultiXact
81926 has invalid next offset STATEMENT: select * from tbl2 where id =
$1 for no key update; ERROR: MultiXact 81941 has invalid next offset
CONTEXT: while scanning block 3 offset 244 of relation "public.tbl2"
automatic vacuum of table "postgres.public.tbl2" Best regards, Dmitry.