Re: Does recovery write to backup_label ?

On Sat, Feb 8, 2020 at 5:05 AM Chapman Flack <chap(at)anastigmatix(dot)net> wrote:
>
> On 2/7/20 2:55 PM, Andres Freund wrote:
>
> >> If the file needs to have 0600 permissions, should there be
> >> a note in the nonexclusive-mode backup docs to say so?
> >
> > I'm not convinced that that's useful. The default is that everything
> > needs to be writable by postgres. The exceptions should be noted if
> > anything, not the default.

+1

> Could this arguably be a special case, as most things in the datadir
> are put there by postgres, but the backup_label is now to be put there
> (and not even 'there' there, but added as a final step only to a
> 'backup-copy-of-there' there) by the poor schmuck who reads the
> non-exclusive backup docs as saying "retrieve this content from
> pg_stop_backup() and preserve in a file named backup_label" and can't
> think of any obvious reason to put write permission on a file
> that preserves immutable history in a backup?

I have no strong objection to add more note about permissions
of the files that the users put in the data directory. If we really
do that, it'd be better to note about not only backup_label
but also other files like tablespace_map, recovery.signal,
promotion trigger file, etc.

Regards,

--
Fujii Masao