Re: Updated backup APIs for non-exclusive backups

On 3/19/16 8:15 AM, Magnus Hagander wrote:

> I've attached an updated patch, which is rebased on current master and
> includes the oid fix.

I've now had a chance to go through this in detail and test thoroughly.
We had a lot of discussion about copying pg_control last and that led
me to believe that there might be some sort of race condition with
multiple backups running concurrently.

I tried every trick I could think of and everything worked as expected
so as far as I can see this requirement only applies to backups taken
from a standby which agrees with the comments in do_pg_stop_backup().

Note that I only tested backups against a master database since that's
what is modified by this patch. I'm still not entirely comfortable with
how backups against a standby are done and it that case still think it
would be best to write the stop wal location into backup_label, but as
you said before that would be a completely separate patch.

So in the end I'm fine with the code as it stands with the exception of
the pg_stop_backup2() naming. I'd prefer a more verbose name here but
I'm unable to come up with anything very good. How about
pg_stop_backup_v2()? This function could also use a few more comments,
at least at the top of the exclusive and non-exclusive blocks.

Except for those minor details I believe this is "ready for committer"
unless anybody has an objection.

--
-David
david(at)pgmasters(dot)net