pg.ddx.io pgsql-admin@postgresql.org mailing list archive
help / color / mirror / Atom feedmax_slot_wal_keep_size
3+ messages / 2 participants
[nested] [flat]
* max_slot_wal_keep_size
@ 2021-08-16 13:58 Scott Ribe <scott_ribe@elevated-dev.com>
0 siblings, 1 reply; 3+ messages in thread
From: Scott Ribe @ 2021-08-16 13:58 UTC (permalink / raw)
To: Pgsql-admin <pgsql-admin@lists.postgresql.org>
If I use max_slot_wal_keep_size to limit disk impact of a down replica, and subsequently a down replica causes PG to hit this limit, is there a particular message that will be logged when the limit is crossed and PG starts to purge WAL?
Context is: trying to debug a failure to bring up a replica, where the failure happened in the middle of a moderately complex chain of events that likely started with a bad disk. (Patroni is involved, FWIW)
--
Scott Ribe
scott_ribe@elevated-dev.com
https://www.linkedin.com/in/scottribe/
--
Scott Ribe
scott_ribe@elevated-dev.com
https://www.linkedin.com/in/scottribe/
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: max_slot_wal_keep_size
@ 2021-08-16 14:08 Alvaro Herrera <alvherre@alvh.no-ip.org>
parent: Scott Ribe <scott_ribe@elevated-dev.com>
0 siblings, 1 reply; 3+ messages in thread
From: Alvaro Herrera @ 2021-08-16 14:08 UTC (permalink / raw)
To: Scott Ribe <scott_ribe@elevated-dev.com>; +Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
On 2021-Aug-16, Scott Ribe wrote:
> If I use max_slot_wal_keep_size to limit disk impact of a down
> replica, and subsequently a down replica causes PG to hit this limit,
> is there a particular message that will be logged when the limit is
> crossed and PG starts to purge WAL?
>
> Context is: trying to debug a failure to bring up a replica, where the
> failure happened in the middle of a moderately complex chain of events
> that likely started with a bad disk. (Patroni is involved, FWIW)
Yes, you should see
invalidating slot "..." because its restart_lsn ... exceeds max_slot_wal_keep_size
However, there was a bug fixed recently in that area, whereby the slot
would be invalidated but the space would not be freed; the fix was on
July 16th and it was released together with last week's minors:
Author: Alvaro Herrera <alvherre@alvh.no-ip.org>
Branch: master [ead9e51e8] 2021-07-16 12:07:30 -0400
Branch: REL_14_STABLE [e5bcbb107] 2021-07-16 12:07:30 -0400
Branch: REL_13_STABLE Release: REL_13_4 [866237a6f] 2021-07-16 12:07:30 -0400
Advance old-segment horizon properly after slot invalidation
When some slots are invalidated due to the max_slot_wal_keep_size limit,
the old segment horizon should move forward to stay within the limit.
However, in commit c6550776394e we forgot to call KeepLogSeg again to
recompute the horizon after invalidating replication slots. In cases
where other slots remained, the limits would be recomputed eventually
for other reasons, but if all slots were invalidated, the limits would
not move at all afterwards. Repair.
Backpatch to 13 where the feature was introduced.
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reported-by: Marcin Krupowicz <mk@071.ovh>
Discussion: https://postgr.es/m/17103-004130e8f27782c9@postgresql.org
--
Álvaro Herrera 39°49'30"S 73°17'W — https://www.EnterpriseDB.com/
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: max_slot_wal_keep_size
@ 2021-08-16 14:27 Scott Ribe <scott_ribe@elevated-dev.com>
parent: Alvaro Herrera <alvherre@alvh.no-ip.org>
0 siblings, 0 replies; 3+ messages in thread
From: Scott Ribe @ 2021-08-16 14:27 UTC (permalink / raw)
To: Alvaro Herrera <alvherre@alvh.no-ip.org>; +Cc: Pgsql-admin <pgsql-admin@lists.postgresql.org>
> On Aug 16, 2021, at 8:08 AM, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> Yes, you should see
> invalidating slot "..." because its restart_lsn ... exceeds max_slot_wal_keep_size
Thank you; that's exactly what I need to cut through the log noise in splunk and see if this happened
^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2021-08-16 14:27 UTC | newest]
Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2021-08-16 13:58 max_slot_wal_keep_size Scott Ribe <scott_ribe@elevated-dev.com>
2021-08-16 14:08 ` Alvaro Herrera <alvherre@alvh.no-ip.org>
2021-08-16 14:27 ` Scott Ribe <scott_ribe@elevated-dev.com>
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox