Re: Updated backup APIs for non-exclusive backups - Mailing list pgsql-hackers

* Magnus Hagander (magnus@hagander.net) wrote:
> On Sun, Apr 24, 2016 at 5:37 AM, Bruce Momjian <bruce@momjian.us> wrote:
>
> > On Fri, Apr 22, 2016 at 11:53:46AM -0400, Robert Haas wrote:
> > > On Wed, Apr 20, 2016 at 1:32 PM, Magnus Hagander <magnus@hagander.net>
> > wrote:
> > > > Note that we have not marked them as deprecated. We're just giving
> > warnings
> > > > that they will be deprecated.
> > >
> > > But I think that is being said here is that maybe they won't be
> > > deprecated, at least not any time soon.  And therefore maybe we
> > > shouldn't say so.
> > >
> > > Frankly, I think that's right.  It is one thing to say that the new
> > > method is preferred - +1 for that.  But the old method is going to
> > > continue to be used by many people for a long time, and in some cases
> > > will be superior.  That's not something we can deprecate, unless I'm
> > > misunderstanding the situation.
> >
> > I agree with Robert.  One the one hand we are saying pg_stop_backup()
> > doesn't work well in psql because you get those two file contents output
> > that you have to write, and on the other hand we are saying we are going
> > to deprecate the method that does work well in psql?  I must be missing
> > something too, as that makes no sense.
>
> I don't agree. I don't see how "making a backup using psql" is more
> important than "making a backup without potentially dangerous sideeffects".
> But if others don't agree, could one of you at least provide an example of
> how you'd like the docs to read in a way that doesn't deprecate the unsafe
> way but still informs the user properly?

I'm with Magnus on this, primairly because I've come to understand just
how dangerous the old backup method is.  That method *should* be
deprecated and discouraged.  A backup method which means your database
doesn't restart properly if the system crashes during the backup is
*bad*.

Fixing that means using something more complicated than the old method
and that's a bit of a pain in psql, but that doesn't mean we should tell
people that the old method is an acceptable approach.

Perhaps we can look at improving psql to make it easier to use it for
the new backup method but, honestly, all these hackish scripts to do
backups aren't doing a lot of things that a real backup solution needs
to do.  Improving psql for this is a bit like new paint on the titanic.

Thanks!

Stephen