Re: incremental backups

From: Richard Huxton <dev(at)archonet(dot)com>
To: Rick Gigger <rick(at)alpinenetworking(dot)com>
Cc: Csaba Nagy <nagy(at)ecircle-ag(dot)com>, pgsql general <pgsql-general(at)postgresql(dot)org>
Subject: Re: incremental backups
Date: 2006-01-27 10:33:01
Message-ID: 43D9F6DD.7020401@archonet.com
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Rick Gigger wrote:
> Um, no you didn't read my email at all. I am aware of all of that and
> it is clearly outlined in the docs. My email was about a specific
> detail in the process. Please read it if you want to know what my
> actual question was.

I'm not sure your email is quite right as regards the process. You need:
1. the filesystem backup
2. the WAL file indicated in the history-file
3. all the WAL files later than that
to get up to "now".

If you don't want to replay up to "now" then you will not need some of
the more recent WAL files. You can't afford to throw them away though
since you've got a rolling backup system running and the whole point is
so you can recover to any point you like.

You can however throw away any WAL files older than that indicated in
the history file for your current filesystem-backup. You can then only
restore from that point in time forward.

There is no "last one" in the WAL set unless you know the time you want
to restore to. Indeed, the "last one" might not be "full" yet and
therefore archived if you want to restore to 10 seconds ago.

Or am I mis-understanding your email too?

--
Richard Huxton
Archonet Ltd

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