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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Rodrigo Rosenfeld Rosas <rr.rosas@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query completed in < 1s in PG 9.1 and ~ 700s in PG 9.2
Date: Wed, 07 Nov 2012 11:58:34 -0500
Message-ID: <10569.1352307514@sss.pgh.pa.us> (raw)
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	<50995D7C.9020108@gmail.com>
	<17866.1352229874@sss.pgh.pa.us>
	<50996583.2080703@gmail.com>
	<18371.1352231105@sss.pgh.pa.us>
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Merlin Moncure <mmoncure@gmail.com> writes:
> On Wed, Nov 7, 2012 at 5:16 AM, Rodrigo Rosenfeld Rosas
> <rr.rosas@gmail.com> wrote:
>> This was a great guess! Congrats, Merlin:

> Heh -- that was tom's guess, not mine.  What this does is confirm the
> planner regression and that elevates the importance of Tom's request
> to get sample data so we (he) can fix it.

Well, the fact that it's a planner runtime problem and not a
quality-of-plan problem is new information (I'd been assuming the
latter).  Given that, it's possible it's already fixed:
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=ca2d6a6cef5740b29406980eb8d21d44da...
but I'd still want to see a test case to be sure.  In any case,
it's not clear what's the critical difference between the "fast" and
"slow" versions of the query.

			regards, tom lane




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