From: Jakub Ouhrabka <kuba@comgate.cz>
To: pgsql-performance@postgresql.org
To: josh@agliodbs.com
Subject: Re: Write-heavy pg_stats_collector on mostly idle server
Date: Tue, 08 Feb 2011 09:41:12 +0100
Message-ID: <4D5101A8.10503@comgate.cz> (raw)
In-Reply-To: <4D509EE1.4070305@agliodbs.com>
References: <4D4C4E15.20401@agliodbs.com>
<AANLkTinpWWrDHR9KJNebgtbvpXpL4UdQszD0GxF+FWWu@mail.gmail.com>
<4D507920.2030909@agliodbs.com>
<1297120356.18411.197.camel@jd-desktop>
<AANLkTin5T+KartVKBjYRJuCNDEcTUAJkMW6Zna6uJi1Q@mail.gmail.com>
<4D509EE1.4070305@agliodbs.com>
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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To: pgsql-performance@postgresql.org
Cc: kuba@comgate.cz, josh@agliodbs.com
Subject: Re: Write-heavy pg_stats_collector on mostly idle server
In-Reply-To: <4D5101A8.10503@comgate.cz>
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