From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Janes <jeff.janes@gmail.com>
Cc: Claude Speed <gta3user@gmail.com>
Cc: pgsql-bugs@postgresql.org
Subject: Re: new BUG: "postgresql 9.2.3: very long query time"
Date: Fri, 22 Feb 2013 13:34:48 -0500
Message-ID: <5015.1361558088@sss.pgh.pa.us> (raw)
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Jeff Janes <jeff.janes@gmail.com> writes:
> The slowness was introduced with this:
> Use parameterized paths to generate inner indexscans more flexibly.
Try increasing from_collapse_limit to 11 or more.
I'm not exactly sure why the param-path patch might have changed this
behavior, but in any case the collapse limits ought to be the first
thing you think of when you see a crappy plan for a many-relation query.
The curious join nesting in this query makes me wonder if perhaps it was
hand-optimized to fit the behavior of some old version of the planner ...
regards, tom lane
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To: pgsql-bugs@postgresql.org
Cc: tgl@sss.pgh.pa.us, jeff.janes@gmail.com, gta3user@gmail.com
Subject: Re: new BUG: "postgresql 9.2.3: very long query time"
In-Reply-To: <5015.1361558088@sss.pgh.pa.us>
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