Re: index and queries using '<' '>'

From: Bruno Wolff III <bruno(at)wolff(dot)to>
To: Marc Boucher <pgml(at)gmx(dot)net>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: index and queries using '<' '>'
Date: 2004-11-19 15:16:28
Message-ID: 20041119151628.GA23749@wolff.to
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On Fri, Nov 19, 2004 at 15:47:21 +0100,
Marc Boucher <pgml(at)gmx(dot)net> wrote:
> I know that, but I've some comparisons with other queries. And someone
> advised me to try "set enable_seqscan=off;". It takes 50-60% (after
> checking right now) less to use the index. Unfortunately I can't use this
> setting, the query being part of a larger query (joins), and the time
> gained on this particular index is partially lost on the joins.

Tweaking random_page_cost may help. The default is 4, which is often too
high. It is supposed to represent the relative cost of retrieving disk
blocks in a random order as compared to retrieving them in sequential
order. Lowering this value will make index scans look better. Than value
should not be lowered below 1.

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