Keepalive for max_standby_delay
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From: Heikki Linnakangas on 3 Jul 2010 07:59 On 02/07/10 23:36, Tom Lane wrote: > Robert Haas<robertmhaas(a)gmail.com> writes: >> I haven't been able to wrap my head around why the delay should be >> LESS in the archive case than in the streaming case. Can you attempt >> to hit me with the clue-by-four? > > In the archive case, you're presumably trying to catch up, and so it > makes sense to kill queries faster so you can catch up. The existing > code essentially forces instant kill when reading from archive, for any > reasonable value of max_standby_delay (because the archived timestamps > will probably be older than that). That's overenthusiastic in my view, > but you can get that behavior if you want it with this patch by setting > max_standby_archive_delay to zero. If you don't want it, you can use > something larger. If you don't think that max_standby_archive_delay > should be less than max_standby_streaming_delay, you can set them the > same, too. It would seem logical to use the same logic for archive recovery as we do for streaming replication, and only set XLogReceiptTime when you have to wait for a WAL segment to arrive into the archive, ie. when restore_command fails. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
From: Heikki Linnakangas on 3 Jul 2010 15:17
On 03/07/10 18:32, Tom Lane wrote: > Heikki Linnakangas<heikki.linnakangas(a)enterprisedb.com> writes: >> It would seem logical to use the same logic for archive recovery as we >> do for streaming replication, and only set XLogReceiptTime when you have >> to wait for a WAL segment to arrive into the archive, ie. when >> restore_command fails. > > That would not do what you want at all in the case where you're > recovering from archive --- XLogReceiptTime would never advance > at all for the duration of the recovery. Do you mean when using something like pg_standby, which does the waiting itself? > It might be useful if you knew that it was a standby-with-log-shipping > situation, but we have no way to tell the difference. With pg_standby etc. you use standby_mode=off. Same with traditional archive recovery. In standby mode, it's on. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers(a)postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers |