Re: Huge number of disk writes after migration to 8.1

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Marcin <migor(at)op(dot)pl>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Huge number of disk writes after migration to 8.1
Date: 2006-01-18 16:38:46
Message-ID: 200601181638.k0IGck600899@candle.pha.pa.us
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Do you mean stats_command_string? I have seen degradation in using that
and am working on a patch for 8.2 to fix it.

---------------------------------------------------------------------------

Marcin wrote:
> Qingqing Zhou wrote:
> > A similar problem was reported before:
> >
> > http://archives.postgresql.org/pgsql-admin/2005-12/msg00266.php
> >
> > But we conclude that's not related to pgstats. See if that's related to
> > your situation.
>
> Unfortunately, I don't think so. The 8.0.3 run just fine. And I don't
> see any pgsql_tmp files. The problems started after migration to 8.1.2.
> I posted to pgsql-bugs, following Tom suggestion.
> BTW, I made some benchmarks on test machine (which is 32bit 2xPIII
> 1.4GHz) with pgbench and I was quite amazed:
> pgbench -S -c 50 -t 10000 -v pgbench
> with stats collector disabled resulted in:
> tps = 3178.346439 (including connections establishing)
> tps = 3183.360731 (excluding connections establishing)
>
> with stats collector enabled, but stats_command_prompt disabled:
> tps = 3143.376908 (including connections establishing)
> tps = 3147.564695 (excluding connections establishing)
>
> and with stats_command_prompt enabled:
> tps = 2446.136610 (including connections establishing)
> tps = 2448.785260 (excluding connections establishing)
>
> However, I didn't notice any suspicious write activity.
>
> Thanks for suggestion,
> --
> Marcin
>
> ---------------------------(end of broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings
>

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