Re: background writer, WAL and snapshot backups

On Wed, 25 Nov 2003, Paul Tuckfield wrote:

> I really like the idea of taking a snapshot backup with postgres, using
> either volume manager or hardware splits in a disk array to get a
> physical backup.

Does anyone else see any value in snapshotting. It would, I image,
essentially work like this: A snapshot command is issued, the background
writer CHECKPOINTS, the background writer/buffer manager writes out all
new data to a different disk partition, any reads also need to look at the
data in the temporary partition, and while this is happening, the main
data directories are being copied some where else. Once it is finished,
everything is tied up again. It would be quite fast and would make
restores rather painless, but it wouldn't be trivial to implement :-)
(could you even handle b-tree or would you have to seqscan any new data?).

Just a thought,

Gavin