Re: count(*) index

From: Bruno Wolff III <bruno(at)wolff(dot)to>
To: Tomka Gergely <tomka(at)zeus(dot)gau(dot)hu>
Cc: psql kezd? lista <pgsql-novice(at)postgresql(dot)org>
Subject: Re: count(*) index
Date: 2005-01-07 19:45:41
Message-ID: 20050107194541.GA15048@wolff.to
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On Fri, Jan 07, 2005 at 19:22:56 +0100,
Tomka Gergely <tomka(at)zeus(dot)gau(dot)hu> wrote:
> Hi!
>
> Yes, i know, mvcc, and can't use indexes. And i know the workaround for
> max() and min(). Is there some workaround for count()?
>
> select count(*) from table where field=1;
>
> and field has a nice index. And this is slooooow.

If there are few records where field=1 then an index will be used.

You may get better performance maintaining a count table using triggers.
This may not work well of there are lots of concurrent updates.

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