On Tue, Mar 14, 2017 at 9:56 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> Cool, thanks for the review. I'm not quite confident that we've found >> all of the bugs here yet, but I think we're moving in the right >> direction. > > I guess the real question here is why isn't Gather Merge more like > Append and MergeAppend? That is, why did you complicate matters > by making it projection capable? That seems like a pretty random > decision from here.
Well, then it would be inconsistent with plain old Gather. I thought about going that route - ripping whatever projection logic Gather has out and teaching the system that it's not projection-capable - but I don't see what that buys us. It's pretty useful to be able to project on top of Gather-type nodes, because they will often be at the top of the plan, just before returning the results to the user. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
