From: Florian Weimer <fweimer@bfk.de>
To: Mark Felder <feld@feld.me>
Cc: pgsql-performance@postgresql.org
Subject: Re: Any experience using "shake" defragmenter?
Date: Mon, 31 Jan 2011 16:44:07 +0000
Message-ID: <82k4hl81m0.fsf@mid.bfk.de> (raw)
In-Reply-To: <op.vp44qo0134t2sn@me-pc.lan>
References: <4D45C607.4070101@vmsinfo.com>
<op.vp44qo0134t2sn@me-pc.lan>
* Mark Felder:
> Why do you feel the need to defrag your *nix box?
Some file systems (such as XFS) read the whole extent list into RAM
when a file is opened. When the extend list is long due to
fragmentation, this can take a *long* time (in the order of minutes
with multi-gigabyte Oracle Berkeley DB files). This phenomenon is
less pronounced with PostgreSQL because it splits large relations into
one-gigabyte chunks, and it writes the files sequentally. But a small
effect is probably still there.
--
Florian Weimer <fweimer@bfk.de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99
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To: pgsql-performance@postgresql.org
Cc: fweimer@bfk.de, feld@feld.me
Subject: Re: Any experience using "shake" defragmenter?
In-Reply-To: <82k4hl81m0.fsf@mid.bfk.de>
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