On Thu, Nov 1, 2018 at 6:14 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Wed, Oct 31, 2018 at 01:09:53PM -0400, Robert Haas wrote:
> > There's no rule whatsoever that a parallel worker can't write to the
> > disk. pg_start_backup and pg_stop_backup have to be
> > parallel-restricted because, when used in non-exclusive mode, they
> > establish backend-local state that wouldn't be synchronized with the
> > state in the workers -- namely the information that a non-exclusive
> > backup is in progress.
>
> Okay, but likely we would not want to signal the postmaster
> unnecessarily, no?
Right, but I think the question here is whether it is safe to execute
this function in parallel workers? I don't see any meaningful use
cases where anyone wants to run this via parallel workers even if it
is safe to execute via them, but I think that is not how we decide
parallel-safe property of any functions.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com