Re: pg_stop_backup(wait_for_archive := true) on standby server

On Mon, Jul 24, 2017 at 6:45 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> What the change would do is make the pg_stop_backup() caller block until
> the last WAL is archvied, and perhaps that ends up taking hours, and
> then the connection is dropped for whatever reason and the backup fails
> where it otherwise.... what? wouldn't have been valid anyway at that
> point, since it's not valid until the last WAL is actually archived.
> Perhaps eventually it would be archived and the caller was planning for
> that and everything is fine, but, well, that feels like an awful lot of
> wishful thinking.

Letting users taking unconsciously inconsistent backups is worse than
potentially breaking scripts that were actually not working as
Postgres would expect. So I am +1 for back-patching a lighter version
of the proposed patch that makes the wait happen on purpose.

>> > I'd hate to have to do it, but we could technically add a GUC to address
>> > this in the back-branches, no? I'm not sure that's really worthwhile
>> > though..
>>
>> That would be mighty ugly.
>
> Oh, absolutely agreed.

Yes, let's avoid that. We are talking about a switch aimed at making
backups potentially inconsistent.
--
Michael