From: "Liviu Ionescu" <ilgb@livius.net>
To: <pgsql-performance@postgresql.org>
Subject: Re: performance drop on 8.2.4, reverting to 8.1.4
Date: Fri, 18 May 2007 14:51:42 +0300
Message-ID: <008901c79942$e7136e10$653e10ac@ilgvaio>
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Importance: Normal

> This seems to be the source of the misestimation. You might=20
> want to try using "n WHERE n.nodein NOT IN (SELECT nodeid=20
> FROM templates)" instead of "n LEFT JOIN templates USING=20
> (nodeid) WHERE templates.nodeid IS NULL" and see if it helps.

it helped, the new version of the query takes 2303 ms on both 8.1.4 and =
8.2.4.

any idea why the 8.2.4 planner is not happy with the initial select? was =
it just a big chance that it worked in 8.1.4 or the 8.2.4 planner has a =
problem?

or, from another perspective, is the new syntax more portable? what are =
the chances that after upgrading to 8.3.x to encounter new problems?

regards,

Liviu