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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Claudio Freire <klaussfreire@gmail.com>
Cc: Andres Freund <andres@2ndquadrant.com>
Cc: Andrew Dunstan <andrew@dunslane.net>
Cc: Heikki Linnakangas <hlinnakangas@vmware.com>
Cc: Craig Ringer <craig@2ndquadrant.com>
Cc: Merlin Moncure <mmoncure@gmail.com>
Cc: David Greco <David_Greco@harte-hanks.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Poor performance using CTE
Date: Wed, 21 Nov 2012 12:09:50 -0500
Message-ID: <6038.1353517790@sss.pgh.pa.us> (raw)
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Claudio Freire <klaussfreire@gmail.com> writes:
> collapse_cte_limit?

The join collapse limits address a completely different problem (ie,
explosion of planning time with too many relations), and are pretty much
useless as a model for this.  As multiple people told you already,
optimization fences are typically wanted for only specific subqueries.

			regards, tom lane




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