On Wed, Apr 8, 2020 at 11:17 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > Amit Langote <amitlangot...@gmail.com> writes: > > On Tue, Apr 7, 2020 at 2:41 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > >> I *think* that it might be all right, because although what we > >> are matching to is a user-written COALESCE() not an actual > >> FULL JOIN USING column, it has to behave in somewhat the same > >> way. In particular, by construction it must be a coalesce of > >> some representation of the matching partition columns of the > >> full join's inputs. So, even though it might go to null in > >> different cases than an actual USING variable would do, it > >> does not break the ability to partition the join. > > > Seems fine to me too. Maybe users should avoid writing it by hand if > > possible anyway, because even slight variation in the way it's written > > will affect this: > > I'm not particularly concerned about users intentionally trying to trigger > this behavior. I just want to be sure that if someone accidentally does > so, we don't produce a wrong plan. > > I waited till after the "advanced partitionwise join" patch went > in because that seemed more important (plus I wondered a bit if > that would subsume this). But this patch seems to still work, > and the other thing doesn't fix the problem, so pushed.
Thank you for your time on this. -- Amit Langote EnterpriseDB: http://www.enterprisedb.com
