| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | "Pavlov, Vladimir" <Vladimir(dot)Pavlov(at)tns-global(dot)ru> |
| Cc: | 'Adrian Klaver' <adrian(dot)klaver(at)aklaver(dot)com>, "'pgsql-general(at)postgresql(dot)org'" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Multixacts wraparound monitoring |
| Date: | 2016-03-30 21:16:49 |
| Message-ID: | 20160330211649.GA41557@alvherre.pgsql |
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| Lists: | pgsql-general |
Pavlov, Vladimir wrote:
> Yes, VACUUM helps to solve the problem and the WARNING gone away.
> But, the problem is that the VACUUM for the entire database (2.4T) takes over 7 hours, and it has to run every 15-20 hours (about 300 millions transactions), otherwise:
> ERROR: multixact "members" limit exceeded - and server stops working.
> The question is how to start the VACUUM at least once in three days.
You should have *started* the thread with this information.
My bet is that your multixacts are overly large and that's causing
excessive vacuuming work; this is likely due to bug #8470 (which is
fixed in 9.5 and master but not 9.3 and 9.4) and my bet is that you
would very much benefit from the patch I posted in
https://www.postgresql.org/message-id/20150620043650.GX133018%40postgresql.org
I didn't actually verify this; you could with some arithmetic on the
deltas in multixact counters in pg_controldata output that you could
take periodically.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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