Re: poor pefrormance with regexp searches on large tables

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Grzegorz Blinowski" <g(dot)blinowski(at)gmail(dot)com>, <pgsql-performance(at)postgresql(dot)org>
Subject: Re: poor pefrormance with regexp searches on large tables
Date: 2011-08-10 15:27:57
Message-ID: 4E425D2D020000250003FD32@gw.wicourts.gov
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Grzegorz Blinowski <g(dot)blinowski(at)gmail(dot)com> wrote:

> Some performance params from postgresql.conf:

Please paste the result of running the query on this page:

http://wiki.postgresql.org/wiki/Server_Configuration

For a start, the general advice is usually to start with
shared_buffers at the lesser of 25% of system RAM or 8 GB, and
adjust from there based on benchmarks. So you might want to try 4GB
for that one.

Just to confirm, you are using 2 Phase Commit? (People sometimes
mistake the max_prepared_transactions setting for something related
to prepared statements.)

I concur with previous advice that using one regular expression
which matches all of the terms is going to be a lot faster than
matching each small regular expression separately and then combining
them.

-Kevin

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