I wonder if this idea might be taken a little further, to allow
read-only tablespaces?
This would allow old partitions in very large databases to be kept on
read-only media, and would allow normal backups to ignore this
unchanging set of data.
It also allows for certain specific optimisations for this type of data,
as the MVCC rules are now relaxed. Inclusion of a row in a read-only
index is now enough to guarantee the visibility of that row to all
backends, and fetches based solely on the index now become possible.
FWIW, Oracle does something like this. Just a thought.
__
Marc
On Mon, 2005-11-21 at 09:53 -0400, pgsql-hackers-owner@postgresql.org
wrote:
> Date: Sun, 20 Nov 2005 22:39:49 +0200 (EET)
> From: Heikki Linnakangas <hlinnaka@iki.fi>
> To: pgsql-hackers@postgresql.org
> Subject: Data directory on read-only media
> Message-ID: <Pine.OSF.4.61.0511201815450.399601@kosh.hut.fi>
>
> Hi,
>
> I've been thinking about running postgres from read-only media. It's
> handy for creating demo CDs etc. I hacked together a patch that
> allows
> you to run Postgres without write permissions to the data directory.
>