On Thu, Aug 21, 2014 at 11:01 AM, Andrew Gierth <andrew@tao11.riddles.org.uk> wrote: >>>>>> "Heikki" == Heikki Linnakangas <hlinnakangas@vmware.com> writes: > Heikki> Uh, that's ugly. The EXPLAIN out I mean; as an implementation > Heikki> detail chaining the nodes might be reasonable. But the above > Heikki> gets unreadable if you have more than a few grouping sets. > > It's good for highlighting performance issues in EXPLAIN, too.
Perhaps so, but that doesn't take away from Heikki's point: it's still ugly. I don't understand why the sorts can't all be nested under the GroupAggregate nodes. We have a number of nodes already (e.g. Append) that support an arbitrary number of children, and I don't see why we can't do the same thing here.
I don't think so showing sort and aggregation is bad idea. Both can have a different performance impacts