encouraging index-only scans

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: pgsql-perform <pgsql-performance(at)postgresql(dot)org>
Subject: encouraging index-only scans
Date: 2012-12-12 21:06:52
Message-ID: 50C8F1EC.9010801@dunslane.net
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A client is testing a migration from 9.1 to 9.2, and has found that a
large number of queries run much faster if they use index-only scans.
However, the only way he has found to get such a plan is by increasing
the seq_page_cost to insanely high levels (3.5). Is there any approved
way to encourage such scans that's a but less violent than this?

cheers

andrew

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