From: | Jakub Ouhrabka <kuba(at)comgate(dot)cz> |
---|---|
To: | pgsql-performance(at)postgresql(dot)org, josh(at)agliodbs(dot)com |
Subject: | Re: Write-heavy pg_stats_collector on mostly idle server |
Date: | 2011-02-08 08:41:12 |
Message-ID: | 4D5101A8.10503@comgate.cz |
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Lists: | pgsql-performance |
Hi Josh,
it's "known" issue, see this thread:
http://archives.postgresql.org/pgsql-hackers/2010-02/thrd6.php#01290
HTH,
Kuba
Dne 8.2.2011 2:39, Josh Berkus napsal(a):
>
>> Ooops.
>> It looks like you are right, see ./src/backend/postmaster/pgstat.c
>>
>> 3c2313f4 (Tom Lane 2008-11-03 01:17:08 +0000 2926)
>> if (last_statwrite< last_statrequest)
>> 70d75697 (Magnus Hagander 2008-08-05 12:09:30 +0000 2927)
>> pgstat_write_statsfile(false);
>
> This is a different issue. This is happening because we have a bunch of
> databases (25 to 35) and as a result autovacuum is requesting the stats
> file rather frequently. And autovacuum for whatever reason won't accept
> a stats file more than 10ms old, so it pretty much rewrites the stats
> file on every request.
>
> At least, that's my reading of it after poking around and talking to
> Gierth.
>
> It seems like that 10ms window for autovac is way too small.
>
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