Transaction wraparound vacuum synchronicity
От | Michael Graham |
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Тема | Transaction wraparound vacuum synchronicity |
Дата | |
Msg-id | 1299667945.7102.121.camel@brutus обсуждение исходный текст |
Ответы |
Re: Transaction wraparound vacuum synchronicity
Re: Transaction wraparound vacuum synchronicity |
Список | pgsql-general |
Hi all, I have a database with a number of tables that are partitioned monthly, after that the tables are mostly read only (on rare occasions we may delete from a table but normally we just drop the partitions). Recently I've noticed that we have a lot of these tables are vacuumed around the same time, after a little big of digging I've realised that postgres is vacuuming them to stop xaction wrap around. So for example in a few million xactions (later today) postgres is going to want to vacuum 37 tables for just this reason. I know I can fiddle autovacuum_freeze_max_age and vacuum_freeze_min_age to change how regularly the tables have this occur, and I can do this on a per table basis in pg_autovacuum (yes this means I'm running an old version, version 8.2) but what I'm wondering is how other people are breaking this synchronisation? Should I add a random value to the freeze_max_age for all the old tables when I start a new month? Or do the same with the freeze_min_age? Perhaps I should just force a vacuum on some of the tables the break it? Cheers, -- Michael Graham <mgraham@bloxx.com>
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