Re: NOT LIKE much faster than LIKE?

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: Andrea Arcangeli <andrea(at)cpushare(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org
Subject: Re: NOT LIKE much faster than LIKE?
Date: 2006-01-10 02:54:57
Message-ID: 20060109185355.S36990@megazone.bigpanda.com
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On Tue, 10 Jan 2006, Andrea Arcangeli wrote:

> I see. I can certainly fix it by stopping using LIKE. But IMHO this
> remains a bug, since until the statistics about the numberof matching
> rows isn't estimated well, you should not make assumptions on LIKE/NOT
> LIKE. I think you can change the code in a way that I won't have to
> touch anything, and this will lead to fewer surprises in the future IMHO.

I doubt it, since I would expect that this would be as large a
pessimization for a larger fraction of people than it is an optimization
for you.

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