Re: Updated backup APIs for non-exclusive backups

Greetings,

* Laurenz Albe (laurenz.albe@cybertec.at) wrote:
> On Sun, 2018-11-25 at 16:04 -0500, Stephen Frost wrote:
> > > Yes, you can come up with a post-backup script that somehow communicates
> > > with your pre-backup script to get the information, but it sure is
> > > inconvenient.  Simplicity is good in backup solutions, because complicated
> > > things tend to break more easily.
> >
> > Not sure what communication is necessary here..?   The data needed for the backup
> > label file comes from pg_stop_backup in a non-exclusive backup.
>
> Right, and pg_stop_backup has to be run from the "pre-backup" script.

No, pg_stop_backup has has to be run by a process that's been connected
since the pre-backup script ran, but you could certainly have some
process that starts from pre-backup, detaches, and then waits for a
signal from the post-backup script to run pg_stop_backup and record the
results somewhere.

Yes, that's rather annoying to do from a bash script, but I'm well past
the point of thinking that bash scripts are a good way to run backups in
PG.  Your efforts in this area might be better put to use by writing a
good tool which works with the non-exclusive API but can be called from
the pre/post backup scripts your backup solution provides.
Unfortunately, it seems pretty unlikely that there's a good generic way
to write such a tool or we could include it in PG.

Thanks!

Stephen