Re: performance with triggers depends on table size?

From: Christian Mock <cm(at)coretec(dot)at>
To: pgsql-general(at)postgresql(dot)org
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: performance with triggers depends on table size?
Date: 2002-08-14 10:29:46
Message-ID: 20020814102945.GA20427@notemock.coretec.at
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On Mon, Aug 12, 2002 at 06:21:05PM -0400, Tom Lane wrote:

> Perhaps what it's actually dependent on is the size of the stats table?
> Do you have indexes on the stats table, and if so are they being used
> by the trigger's queries?

I started the insert on the real database to copy some 3.6 million records
between the tables, and plotted the timings -- now (with about half a
million records done) you can see the time it takes to insert a row
actually goes in a sawtooth pattern -- cf.
http://www.coretec.at/~cm/insert-trigger.gif
which has msec/inserted row on the Y axis and number of rows in the
"output" table on the X axis.

Can anybody explain this?

Note that these are not the tables from the perl script I posted, but
something more complex with a few foreign key constraints, but the
trigger is basically doing the same thing.

Oh, and:

=> select version();
version
---------------------------------------------------------------
PostgreSQL 7.2.1 on i686-pc-linux-gnu, compiled by GCC 2.95.4

on Debian/Stable (3.0).

Regards,

cm.

--
Christian Mock Wiedner Hauptstrasse 15
Senior Security Engineer 1040 Wien
CoreTEC IT Security Solutions GmbH +43-1-5037273

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