Chris Cogdon <chris(at)cogdon(dot)org> writes:
> Hi folks! Ive a query where adding a rollup to the group by switches to
> GroupAggregate unexpectedly, where the standard GROUP BY uses
> HashAggregate.
The current implementation of rollup doesn't support using hashed
aggregation. I don't know if that's for lack of round tuits or because
it's actually hard, but it's not the planner's fault.
regards, tom lane