From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
To: David Rowley <dgrowley@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter_e@gmx.net>
Cc: pgsql-hackers@postgresql.org
Subject: Re: [PATCHES] TODO item: Implement Boyer-Moore searching (First time hacker)
Date: Thu, 11 Sep 2008 10:20:50 +0300
Message-ID: <48C8C6D2.2010809@enterprisedb.com> (raw)
In-Reply-To: <17EF6EF77BD7405E86761C688A73BAB4@amd64>
References: <17EF6EF77BD7405E86761C688A73BAB4@amd64>
David Rowley wrote:
> The thing that surprised me was that string_to_array didn't perform as well.
> I expected single character searches to perform a little better. I can't
> think why it would be slower now.
Yes, that's strange. I tried to reproduce that here, with a CVS snapshot
before the patch, and after. With quick testing with psql and \timing
and the same query you had in that spreadsheet, I couldn't see that kind
of performance degradation. Oprofile suggests that, on the contrary,
slightly less time is spent in text_position_next() after the patch, and
slightly more in text_position_setup(). Together they account for ~10%
of CPU time in both tests, so a small difference there would be
insignificant anyway in that test case.
I think we're fine.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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To: pgsql-patches@postgresql.org
Cc: heikki.linnakangas@enterprisedb.com, dgrowley@gmail.com, tgl@sss.pgh.pa.us, peter_e@gmx.net, pgsql-hackers@postgresql.org
Subject: Re: [PATCHES] TODO item: Implement Boyer-Moore searching (First time hacker)
In-Reply-To: <48C8C6D2.2010809@enterprisedb.com>
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