Date: Thu, 20 Oct 2005 12:16:34 +0200
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
To: pgsql-performance@postgresql.org
Subject: Re: Materializing a sequential scan
Message-ID: <20051020101634.GB11055@samfundet.no>
References: <20051019174544.GA32303@samfundet.no>
	<4248.1129783045@sss.pgh.pa.us>
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On Thu, Oct 20, 2005 at 12:37:25AM -0400, Tom Lane wrote:
> That mdb_gruppekobling_transitiv_tillukning function looks awfully
> grotty ... how many rows does it return, and how long does it take to
> run by itself?  How often does its temp table get vacuumed?  A quick
> band-aid might be to use TRUNCATE instead of DELETE FROM to clean the
> table ... but if I were you I'd try to rewrite the function entirely.

It returns 752 rows, and the table is autovacuumed. If I run the queries
manually, they take ~15ms in all -- for some odd reason, the function in itself
varies between 40 and 500ms, though...

I tried using TRUNCATE earlier, but if anything, it made the function slower
(might just have been zero difference, though).  I also had written the
function differently (using a series of depth-first searches), but it was
awfully slow even after a lot of tweaking, so it was not really worth it...

/* Steinar */
-- 
Homepage: http://www.sesse.net/