Re: 7k records into Sort node, 4.5m out?

From: Josh Berkus <josh(at)agliodbs(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: 7k records into Sort node, 4.5m out?
Date: 2012-08-15 21:02:35
Message-ID: 502C0E6B.1040402@agliodbs.com
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On 8/15/12 1:51 PM, Tom Lane wrote:
> Christophe Pettus <xof(at)thebuild(dot)com> writes:
>> On Aug 13, 2012, at 7:11 PM, Tom Lane wrote:
>>> The whole thing looks a bit weird to me --- why did it not use a
>>> nestloop join with inner indexscan on charlie? With 7000 rows on the
>>> other side, the estimated cost for that shouldn't have been more than
>>> about 30000 ...
>
>> Here's the same query with set enable_megejoin = off. All of the other query tuning parameters are default.
>
>> http://explain.depesz.com/s/dqO
>
> Maybe you had better show us the actual query, and the table/index
> definitions. Because it's sure making odd choices here. This seems
> like the wrong join order altogether ...

We'll need to do that off-list for confidentiality reasons.

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com

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