From: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl>
To: Pgsql-Performance <pgsql-performance@postgresql.org>
Subject: pgbench results interpretation?
Date: Tue, 01 Nov 2005 09:03:09 +0100
Message-ID: <1130832189.21036.19.camel@Panoramix> (raw)
Hi,
I am trying to optimize my Debian Sarge AMD64 PostgreSQL 8.0
installation, based on the recommendations from "the Annotated
POSTGRESQL.CONF Guide for
PostgreSQL" (http://www.powerpostgresql.com/Downloads/annotated_conf_80.html). To see the result of the recommendations I use pgbench from postgresql-contrib.
I have 3 questions about pgbench:
1. Is there a repository somewhere that shows results, using and
documenting different kinds of hard- and software setups so that I can
compare my results with someone elses?
2. Is there a reason for the difference in values from run-to-run of
pgbench:
The command I used (nothing else is done on the machine, not even mouse
movement):
jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test
Results for 4 consecutive runs:
tps = 272.932982 (including connections establishing)
tps = 273.262622 (excluding connections establishing)
tps = 199.501426 (including connections establishing)
tps = 199.674937 (excluding connections establishing)
tps = 400.462117 (including connections establishing)
tps = 401.218291 (excluding connections establishing)
tps = 223.695331 (including connections establishing)
tps = 223.919031 (excluding connections establishing)
3. It appears that running more transactions with the same amount of
clients leads to a drop in the transactions per second. I do not
understand why this is (a drop from more clients I do understand). Is
this because of the way pgbench works, the way PostgrSQL works or even
Linux?
jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10 test
tps = 379.218809 (including connections establishing)
tps = 461.968448 (excluding connections establishing)
jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 100 test
tps = 533.878031 (including connections establishing)
tps = 546.571141 (excluding connections establishing)
jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 1000 test
tps = 204.344440 (including connections establishing)
tps = 204.533627 (excluding connections establishing)
jkr@Panoramix:/usr/lib/postgresql/8.0/bin$ ./pgbench -c 10 -t 10000 test
tps = 121.486803 (including connections establishing)
tps = 121.493681 (excluding connections establishing)
TIA
--
Groeten,
Joost Kraaijeveld
Askesis B.V.
Molukkenstraat 14
6524NB Nijmegen
tel: 024-3888063 / 06-51855277
fax: 024-3608416
e-mail: J.Kraaijeveld@Askesis.nl
web: www.askesis.nl
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To: pgsql-performance@postgresql.org
Cc: J.Kraaijeveld@Askesis.nl
Subject: Re: pgbench results interpretation?
In-Reply-To: <1130832189.21036.19.camel@Panoramix>
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