Re: detecting binary backup in progress

On 2013-06-01 17:05:57 +0900, Michael Paquier wrote:
> On Sat, Jun 1, 2013 at 4:55 AM, Alvaro Herrera <alvherre@2ndquadrant.com>wrote:
> 
> > Heikki Linnakangas wrote:
> >
> > > The manual says:
> > > >pg_is_in_backup()    bool    True if an on-line exclusive backup is
> > still in progress.
> > >
> > > So clearly that is intentional. That could use some rephrasing,
> > > though; a layman won't know what an "exclusive backup" is.
> >
> > Heck, I don't understand what it is either.
> >
> Same here. Does it mean taking a backup not with pg_basebackup but by
> executing yourself external operations between pg_start/stop_backup calls?

Basically yes. pg_start/stop_backup places the backup label into the data
directory itself so there can only be one of them at a time since it has
to have a fixed name. With the streaming protocol the backup label is
only added to the streamed data, so there can be multiple ones at the
same time.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services