Re: 7.3 vs 7.2 - different query plan, bad performance

From: Bruno Wolff III <bruno(at)wolff(dot)to>
To: Ryszard Lach <ryszard(at)lach(dot)name>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: 7.3 vs 7.2 - different query plan, bad performance
Date: 2003-06-13 18:54:05
Message-ID: 20030613185405.GB19711@wolff.to
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On Fri, Jun 13, 2003 at 20:45:06 +0200,
Ryszard Lach <siaco(at)autograf(dot)pl> wrote:

> I can't understand where comes the big difference in query plan from, and
> (that's more important) - how to force postgres 7.3 to execute it more
> efficient?

I am guessing that your are really using 7.3.x and not 7.3. There was
a bug in 7.3 that was fixed in 7.3.1 or 7.3.2 with subselects. However
this fix was made with safety in mind (as it was a point release)
and resulted in some queries running slower. A complete fix was made for
7.4. To test to see if this is really the problem, you could try a 7.4
snapshot or 7.3 to see if you get improved plans.

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