On Tue, Dec 6, 2016 at 1:07 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> Done. > > The comment seems quite confused now: > > * If a tuple count was supplied or data is being written to relation, we > * must force the plan to run without parallelism, because we might exit > * early. > > Exit early is exactly what we *won't* do if writing to an INTO rel, so > I think this will confuse future readers. I think it should be more like > > * If a tuple count was supplied, we must force the plan to run without > * parallelism, because we might exit early. Also disable parallelism > * when writing into a relation, because [ uh, why exactly? ] > > Considering that the writing would happen at top level of the executor, > and hence in the parent process, it's not actually clear to me why the > second restriction is there at all: can't we write tuples to a rel even > though they came from a parallel worker? In any case, the current wording > of the comment is a complete fail at explaining this.
Oops. You're right. [ uh, why exactly? ] -> no database changes whatsoever are allowed while in parallel mode. (This restriction might be lifted someday, but right now we're stuck with it.) -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers