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From: Josh Berkus <josh@agliodbs.com>
To: pgsql-performance@postgresql.org
Subject: Re: Postgres refusing to use >1 core
Date: Wed, 11 May 2011 18:14:22 -0700
Message-ID: <4DCB346E.8070608@agliodbs.com> (raw)
In-Reply-To: <4DCB0802.9060505@peak6.com>
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	<4DC81A3F020000250003D433@gw.wicourts.gov>
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	<4DC81D56020000250003D438@gw.wicourts.gov>
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	<4DC8B893.3060908@postnewspapers.com.au>
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	<4DCAB3A1.2090507@peak6.com>
	<201105111953.060147@ms14.lnh.mail.rcn.net>
	<4DCB0802.9060505@peak6.com>

On 5/11/11 3:04 PM, Shaun Thomas wrote:
> The original query, with our very large tables, ran for over *two hours*
> thanks to a nested loop iterating over the subquery. My replacement ran
> in roughly 30 seconds. If we were using a newer version of PG, we could
> have used a CTE. But do you get what I mean? Temp tables are a fairly
> common technique, but how would a coder know about CTEs? They're pretty
> new, even to *us*.

For that matter, it would be even better if PostgreSQL realized that a
materialize of the subquery was a better execution plan, and just did it
for you.

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



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