Re: Base Backups from PITR Standby

On Tue, 2007-10-30 at 08:25 -0600, Brian Wipf wrote:

> I'm trying to take a base backup from the standby server in archive
> recovery mode. I don't believe it's possible to connect to it to issue
> pg_start_backup/pg_stop_backup.
>
> http://www.postgresql.org/docs/current/interactive/warm-standby.html#BACKUP-INCREMENTAL-UPDATED

It's safest to shutdown the standby first, take a backup then crank it
up again.

It's possible to do it online in the way you suggest, but only when
running with either full_page_writes = on or when making the backup with
rsync, or another method that uses atomic 8Kb reads. The backup is only
valid if you rollforward past the next restartpoint after the backup
completes, which is not technically the right place but definitely far
enough. So its not exactly for the feint-hearted, at the moment.

--
  Simon Riggs
  2ndQuadrant  http://www.2ndQuadrant.com