Re: like/ilike improvements

From: "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com>
To: "Andrew Dunstan" <andrew(at)dunslane(dot)net>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: like/ilike improvements
Date: 2007-09-19 20:12:56
Message-ID: 1d4e0c10709191312i29d60972t74561f2704bc037c@mail.gmail.com
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On 9/19/07, Andrew Dunstan <andrew(at)dunslane(dot)net> wrote:
> It's at least good to see that the LIKE case has some useful speedup in
> 8.3.

It can be due to your patch or to the varlena header patch. Seqscan is
a bit faster too.

> Can you run the same set of tests in a single byte encoding like latin1?

As discussed on IRC, I'm loading the data in a LATIN1 database for
8.1, 8.2 and 8.3. I'll let you know when I have the results.

> We might have to look at doing on-demand lowering, but in a case like
> yours it looks like we'd still end up lowering almost every character
> anyway, so I'm not quite sure what to do. Note that the 8.2 change was a
> bug fix, so we can't just revert it. Maybe we need to look closely at
> the efficiency of lower().

Yes, I know it's a bug fix but the performance decrease is far from
being negligible in our case.

--
Guillaume

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