Re: On-line backup and point-in-time recovery (PITR) - Mailing list pgsql-admin

From Bruce Momjian
Subject Re: On-line backup and point-in-time recovery (PITR)
Date
Msg-id 200508190301.j7J31Ru16769@candle.pha.pa.us
Whole thread Raw
In response to On-line backup and point-in-time recovery (PITR)  (Enzo D'addario <enzo@pienetworks.com>)
Responses Re: On-line backup and point-in-time recovery (PITR)  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-admin
Enzo D'addario wrote:
> Hi All,
>
> I have a couple of questions regarding On-line backup and point-in-time
> recovery (PITR) in the postgres documentation:
>
> 1.How is it that we can create a tar file of the PG Data directory
> whilst postgres is running?

Whe pg_xlog archived files contain information to recover any
inconsistency in the backup tar file.

> 2.What happens with any DB inserts, updates, deletes etc that occur
> between the SELECT pg_start_backup() and the end of the tar?
> They would be already logged in the WAL files and already applied in the
> tarball, do they then get duplicated during log replay in the recover
> process?

No, the recovery is just like crash recovery and everything comes back
clean, but you do have to recover to a time _after_ the end of the
backup.  If you want to recover to a time during the backup you have to
use the previous backup and xlog files.

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

pgsql-admin by date:

Previous
From: Enzo D'addario
Date:
Subject: On-line backup and point-in-time recovery (PITR)
Next
From: Alvaro Herrera
Date:
Subject: Re: On-line backup and point-in-time recovery (PITR)