Re: pg_start_backup and pg_stop_backup Re: Re: [COMMITTERS] pgsql: Make CheckRequiredParameterValues() depend upon correct

Robert Haas wrote:
> At least as I understand it, even when not using
> archive_mode, streaming replication, or hot standby, it's still
> perfectly legal to use pg_start_backup() to take a hot backup.

Nope. The correct procedure to take a hot backup is described in
http://www.postgresql.org/docs/8.4/interactive/continuous-archiving.html#BACKUP-TIPS.
It involves setting archive_mode=on, and archive_command to a shell
command that normally just returns true, except when backup is in
progress. You can't take a hot backup without archiving (or streaming)
at least temporarily. (except with filesystem-level snapshot capabilities).

Which is unfortunate, really. I wish we had a mode where the server
simply refrained from removing/recycling WAL segments while the backup
is running. You could then just:

1. pg_start_backup()
2. tar the data directory, except for pg_xlog
3. tar pg_xlog
4. pg_stop_backup().

--  Heikki Linnakangas EnterpriseDB   http://www.enterprisedb.com