Re: Is Linux 2.6.5 kernel good enough for production?

From: Greg Stark <gsstark(at)mit(dot)edu>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Is Linux 2.6.5 kernel good enough for production?
Date: 2004-05-17 20:19:27
Message-ID: 87zn86vmb4.fsf@stark.xeocode.com
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Richard Huxton <dev(at)archonet(dot)com> writes:

> Dirk Försterling wrote:
> > There were some dumb queries with timestamps, performing much slower
> > with Linux-2.6.5 compared to Linux-2.4.25:
> > The queries used something like this (ts is a TIMESTAMP):
> > ... AND ts LIKE '2003-04-%'
>
> I'm guessing an index isn't being used because your LANG is something-UTF-8 and
> that got picked up when you recreated your database. Try recreating the
> database with the C locale and see if that does it.

Uhm, under no locale would an index be used for "ts LIKE '2003-04-%'" unless
you have an functional index on ts::text, which would be kind of weird.

You might want to rewrite this as

ts BETWEEN '2003-04-01' AND '2003-04-01'+'1 month'

or something like that. At least this way a straight normal index on ts would
be usable work.

--
greg

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