From: Heikki Linnakangas <heikki@enterprisedb.com>
To: Gábor Farkas <gabor@nekomancer.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: select count(*) performance (vacuum did not help)
Date: Mon, 24 Sep 2007 15:30:09 +0100
Message-ID: <46F7C9F1.1080805@enterprisedb.com> (raw)
In-Reply-To: <46F7C494.1050604@nekomancer.net>
References: <46F7C494.1050604@nekomancer.net>
Gábor Farkas wrote:
> - this table has a lot of updates and inserts, it works very similarly
> to a session-table for a web-application
Make sure you run VACUUM often enough.
> - there is a cron-job that deletes all the old entries, so it's size is
> rougly between 15000 and 35000 entries (it's run daily, and every day
> deletes around 10000 entries)
Running vacuum after these deletes to immediately reclaim the dead space
would also be a good idea.
> - but in the past, the cron-job was not in place, so the table's size
> grew to around 800000 entries (in around 80 days)
That bloated your table, so that there's still a lot of empty pages in
it. VACUUM FULL should bring it back to a reasonable size. Regular
normal non-FULL VACUUMs should keep it in shape after that.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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: heikki@enterprisedb.com, gabor@nekomancer.net
Subject: Re: select count(*) performance (vacuum did not help)
In-Reply-To: <46F7C9F1.1080805@enterprisedb.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