Re: Write-heavy pg_stats_collector on mostly idle server

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От Cédric Villemain
Тема Re: Write-heavy pg_stats_collector on mostly idle server
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Msg-id AANLkTin5T+KartVKBjYRJuCNDEcTUAJkMW6Zna6uJi1Q@mail.gmail.com
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Ответ на Re: Write-heavy pg_stats_collector on mostly idle server  ("Joshua D. Drake" <jd@commandprompt.com>)
Ответы Re: Write-heavy pg_stats_collector on mostly idle server  (Josh Berkus <josh@agliodbs.com>)
Список pgsql-performance
2011/2/8 Joshua D. Drake <jd@commandprompt.com>:
> On Mon, 2011-02-07 at 14:58 -0800, Josh Berkus wrote:
>> >> Anyone seen anything like this before?
>> >>
>> >
>> > it is the expected behavior, IIRC
>>
>> OK.  It just seems kind of pathological for stats file writing to be 10X
>> the volume of data writing.  I see why it's happening, but I think it's
>> something we should fix.
>
> I don't think it is expected. As I recall, it is something we fixed a
> couple of major versions back (8.2?). It used to be that stats would
> write every 500ms. We changed that to when they are asked for (via a
> select from the table or something). Specifically because it could cause
> this type of problem.
>
> Am I thinking of something else?
>
> I remember going back and forth with tgl about this, tgl?

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);


>
> JD
>
>>
>> --
>>                                   -- Josh Berkus
>>                                      PostgreSQL Experts Inc.
>>                                      http://www.pgexperts.com
>>
>
> --
> PostgreSQL.org Major Contributor
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>



--
Cédric Villemain               2ndQuadrant
http://2ndQuadrant.fr/     PostgreSQL : Expertise, Formation et Support

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