Message-ID: <42C887DC.40308@telogis.com>
Date: Mon, 04 Jul 2005 12:50:36 +1200
From: David Mitchell <david.mitchell@telogis.com>
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To: weigelt@metux.de
Cc: postgresql performance list <pgsql-performance@postgresql.org>
Subject: Re: plain inserts and deletes very slow
References: <20050703224537.GA9777@nibiru.borg.metux.de>
	<20050703225707.GB9777@nibiru.borg.metux.de>
In-Reply-To: <20050703225707.GB9777@nibiru.borg.metux.de>
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Did you vacuum full?

When you do lots of inserts and deletes, dead tuples get left behind. 
When you vacuum, postgres will reuse those dead tuples, but if you don't 
vacuum for a long time these tuples will build up lots. Even when you 
vacuum in this case, the dead tuples are still there, although they are 
marked for reuse. Vacuuming full actually removes the dead tuples.

If you vacuum (normal) regularly, then the number of dead tuples will 
stay down, as they are regularly marked for reuse.

David

Enrico Weigelt wrote:
> * Enrico Weigelt <weigelt@metux.de> wrote:
> 
> forgot to mention:
> 
>     + linux-2.6.9
>     + postgres-7.4.6
>     + intel celeron 2ghz
>     + intel ultra ata controller
>     + 768mb ram
> 
> 
> cu


-- 
David Mitchell
Software Engineer
Telogis

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