Re: Updated backup APIs for non-exclusive backups

On Sun, 2018-11-25 at 22:01 +0100, Magnus Hagander wrote:
[about managing backups from pre- and post-file-system-backup scrips]
> I agree with your point that it's not an uncommon thing to need. If a good solution
> for it can be proposed that requires the exclusive backup interface, then I wouldn't
> be against un-deprecating that.  But that's going to require a lot more than just a
> documentation change, IMHO. What could perhaps be handled with a documentation change,
> however, is to document a good way for this type of setup to use the new interfaces.

Good point, and it puts the ball in my court :^)

> > I'm arguing on behalf of users that run a few databases, want a simple backup
> > solution and are ready to deal with the shortcomings.
>
> Those that want a simple backup solution have one -- pg_basebackup.
>
> The exclusive backup API is *not* simple. It is convenient, but it is not simple.
>
> Actually having a simple API that worked with the pre/post backup scripts, that
> would be an improvement that we should definitely want!

Right; unfortunately it is not simple to come up with one that doesn't exhibit
the problems of the existing exclusive backup.

Perhaps it's theoretically impossible.  The goal is to disambiguate what a file
system backup sees in backup mode and what the startup process sees after a crash
in backup mode, and I can't see how that could be done.