From: Jim C. Nasby <jnasby@pervasive.com>
To: Jean-Paul Argudo <jean-paul@argudo.org>
Cc: Olivier Andreotti <olivier.andreotti@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Benchmarck PostgreSQL 8.1.4 MySQL 5.0.20 and Oracle
Date: Fri, 19 May 2006 15:21:35 -0500
Message-ID: <20060519202134.GM64371@pervasive.com> (raw)
In-Reply-To: <446C510A.9040609@argudo.org>
References: <d5d40b330605180257w2a0cb2dei53d81cbe0d7405e@mail.gmail.com>
<446C510A.9040609@argudo.org>
On Thu, May 18, 2006 at 12:48:42PM +0200, Jean-Paul Argudo wrote:
> > autovaccuum = on
>
> Thats a critic point. Personaly I dont use autovacuum. Because I just
> don't want a vacuum to be started ... when the server is loaded :)
>
> I prefer control vacuum process, when its possible (if its not,
> autovacuum is the best choice!), for example, a nighlty vacuum...
This can be problematic for a benchmark, which often will create dead
tuples at a pretty good clip.
In any case, if you are going to use autovacuum, you should cut all the
thresholds and scale factors in half, and set cost_delay to something (I
find 5-10 is usually good).
Depending on your write load, you might need to make the bgwriter more
aggressive, too.
If you can graph some metric from your benchmark over time it should be
pretty easy to spot if the bgwriter is keeping up with things or not; if
it's not, you'll see big spikes every time there's a checkpoint.
> A question for you: after setting up your test database, did you launch
> a vacuum full analyze of it ?
Why would you vacuum a newly loaded database that has no dead tuples?
--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, jean-paul@argudo.org, olivier.andreotti@gmail.com
Subject: Re: Benchmarck PostgreSQL 8.1.4 MySQL 5.0.20 and Oracle
In-Reply-To: <20060519202134.GM64371@pervasive.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox