Re: Query completed in < 1s in PG 9.1 and ~ 700s in PG 9.2

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Merlin Moncure <mmoncure(at)gmail(dot)com>
Cc: Rodrigo Rosenfeld Rosas <rr(dot)rosas(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Query completed in < 1s in PG 9.1 and ~ 700s in PG 9.2
Date: 2012-11-06 17:36:27
Message-ID: 15781.1352223387@sss.pgh.pa.us
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Merlin Moncure <mmoncure(at)gmail(dot)com> writes:
> Problem could also be no statistics (run ANALYZE to test) or some
> other configuration problem (like index locale), or a bona fide
> regression.

I'm wondering about join_collapse_limit in particular --- if that wasn't
cranked up in the 9.1 installation, it would be pure luck if you got a
good query plan for an example like this. Maybe that and/or other
parameter settings didn't get transposed to the 9.2 installation.

regards, tom lane

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