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Re: Strange performance degradation

From: "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Strange performance degradation
Date: 2009-11-20 10:23:22
Message-ID: 20091120102322.GD20234@a-kretschmer.de (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-performance
In response to Lorenzo Allegrucci :
> 
> Hi all,
> 
> I'm experiencing a strange behavior with my postgresql 8.3:
> performance is degrading after 3/4 days of running time but if I
> just restart it performance returns back to it's normal value..
> In normal conditions the postgres process uses about 3% of cpu time
> but when is in "degraded" conditions it can use up to 25% of cpu time.
> The load of my server is composed of many INSERTs on a table, and
> many UPDATEs and SELECT on another table, no DELETEs.
> I tried to run vacuum by the pg_maintenance script (Debian Lenny)
> but it doesn't help. (I have autovacuum off).

Bad idea. Really.

> 
> So, my main question is.. how can just a plain simple restart of postgres
> restore the original performance (3% cpu time)?

You should enable autovacuum.

And you should run vacuum verbose manually and see the output.


Andreas
-- 
Andreas Kretschmer
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