Re: strange performance regression between 7.4 and 8.1

From: Florian Weimer <fweimer(at)bfk(dot)de>
To: "Alex Deucher" <alexdeucher(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: strange performance regression between 7.4 and 8.1
Date: 2007-03-02 08:51:58
Message-ID: 82slco6n9t.fsf@mid.bfk.de
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* Alex Deucher:

> I have noticed a strange performance regression and I'm at a loss as
> to what's happening. We have a fairly large database (~16 GB).

Sorry for asking, but is this a typo? Do you mean 16 *TB* instead of
16 *GB*?

If it's really 16 GB, you should check if it's cheaper to buy more RAM
than to fiddle with the existing infrastructure.

> however the table structure is almost identical (UTF8 on the new one
> vs. C on the old).

Locale settings make a huge difference for sorting and LIKE queries.
We usually use the C locale and SQL_ASCII encoding, mostly for
performance reasons. (Proper UTF-8 can be enforced through
constraints if necessary.)

--
Florian Weimer <fweimer(at)bfk(dot)de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99

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