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From: Rodrigo Rosenfeld Rosas <rr.rosas@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Merlin Moncure <mmoncure@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 19:38:12 -0200
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In-Reply-To: <10569.1352307514@sss.pgh.pa.us>
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Em 07-11-2012 14:58, Tom Lane escreveu:
> 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

Ok, I could finally strip part of my database schema that will allow you 
to run the explain query and reproduce the issue.

There is a simple SQL dump in plain format that you can restore both on 
9.1 and 9.2 and an example EXPLAIN query so that you can see the 
difference between both versions.

Please keep me up to date with regards to any progress. Let me know if 
the commit above fixed this issue.

Thanks in advance,

Rodrigo.

Attachments:

  use_case.tar.bz2 (application/x-tbz, 2.3K) download

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