Re: Remove Deprecated Exclusive Backup Mode

On Wed, Dec 12, 2018 at 1:09 PM David Steele <david(at)pgmasters(dot)net> wrote:

> On 12/11/18 9:05 PM, Robert Haas wrote:
> > On Wed, Dec 12, 2018 at 7:24 AM David Steele <david(at)pgmasters(dot)net>
> wrote:
> >> Attached is the patch.
> >
> > As for my vote, I do not buy the idea that because we're changing some
> > stuff about recovery.conf we should go ahead and do this too. Yes,
> > they are related, but just because you adjust your backup/restore
> > script/tool to cope with one change doesn't mean that you don't have
> > to adjust it some more to cope with the other change.
>
> I think the patch stands on its own. Exclusive backup mode is broken
> and is know to cause problems in the field.
>

Yes, this is a *far* too common thing to be seen in the field IMHO.

Is it super-common? No. But it's by far too common not to be a concern.

We deprecated it three years ago and we have a very capable core backup
> tool that people can use instead.
>

+1.

If we can't get consensus on removing it now, then how about actually
setting a *plan* for when to remove it?

For example, in 12 we could more aggressively deprecate it (such as
actually emitting a WARNING message whenever used?), and then announce
already now that it will be removed in version 13? That will then cover all
those people who didn't read the documentation and find the existing
deprecation notice?

> I also think that the idea that supporting the exclusive backup
> > interface is hurting anything is greatly exaggerated. Whether we keep
> > it or not, we're not forcing anyone to use it.
>
> There are maintenance advantages to getting rid of it. The code has
> become simpler and the documentation has become much simpler. Trying to
> explain the subtle differences between backup methods is difficult and
> only makes the documentation more confusing.
>
> Removing the extra complexity from shutdown also seems like a win. The
> gyrations we went through to try and ensure that backup_label was
> renamed before shutdown were truly agonizing. None of that is necessary
> with the non-exclusive mode.
>

That, too!

--
Magnus Hagander
Me: https://www.hagander.net/ <http://www.hagander.net/>
Work: https://www.redpill-linpro.com/ <http://www.redpill-linpro.com/>