From: Stephan Szabo <sszabo@megazone.bigpanda.com>
To: Robert Davis <robert@faithwestinc.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: explain analyze results are different for each iteration
Date: Tue, 14 Sep 2004 19:07:17 -0700 (PDT)
Message-ID: <20040914190607.Y35716@megazone.bigpanda.com> (raw)
In-Reply-To: <41479917.7010305@faithwestinc.com>
References: <41479917.7010305@faithwestinc.com>
On Tue, 14 Sep 2004, Robert Davis wrote:
> I'm trying to benchmark some complex sql queries. One query, in
> particular, is causing problems -- its cost values can vary from 228
> to 907, its Total Runtimes from 60 ms to 5176 ms. The query plans
> show that the optimizer is choosing different plans for different
> iterations of the same query. Does anyone have any idea what's
> going on here or maybe how I can force Postgres to prefer the faster
> plan?
>
> The query plans are very long (11 tables joined) but I can include
> them if it might help. Thanks for any advice,
11 tables. You might want to see if raising geqo_threshold stabilizes the
plans since IIRC that's the threshold for using the genetic optimizer.
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To: pgsql-sql@postgresql.org
Cc: sszabo@megazone.bigpanda.com, robert@faithwestinc.com
Subject: Re: explain analyze results are different for each iteration
In-Reply-To: <20040914190607.Y35716@megazone.bigpanda.com>
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