Re: Updated backup APIs for non-exclusive backups

Hi,

On 2016-02-10 13:46:05 +0100, Magnus Hagander wrote:
> Per discussionat the developer meeting in Brussels, here's a patch that
> makes some updates to the backup APIs, to support non-exclusive backups
> without using pg_basebackup.

Thanks for following through with this!

> * If the client disconnects with a non-exclusive backup running, the backup
> is automatically aborted. This is the same thing that pg_basebackup does.
> To use these non-exclusive backups the backup software will have to
> maintain a persistent connection to the database -- something that should
> not be a problem for any of the modern ones out there (but would've been
> slightly trickier back in the days when we suggested shellscripts)

I think we might want to make this one optional, but I'm not going to
fight super hard for it.

> * A new version of pg_stop_backup is created, taking an argument specifying
> if it's exclusive or not. The current version of pg_stop_backup() continues
> to work for exclusive backups, with no changes to behavior. The new
> pg_stop_backup will return a record of three columns instead of just the
> value -- the LSN (pglsn), the backup label file (text) and the tablespace
> map file (text).

I wonder if we shouldn't change the API a bit more aggressively. Right
now we return the label and the map - but what if there's more files at
some later point? One way would be to make it a SETOF function returning
'filename', 'content' or such. Makes it less clear what to do with the
lsn admittedly.

Regards,

Andres