Re: hashagg slowdown due to spill changes

Hi,

On 2020-06-23 09:23:57 -0700, Melanie Plageman wrote:
> On Mon, Jun 22, 2020 at 9:02 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > It's not this patch's fault, but none, really none, of this stuff should
> > be in the executor.
> >
> >
> Were you thinking it could be done in grouping_planner() and then the
> bitmaps could be saved in the PlannedStmt?
> Or would you have to wait until query_planner()? Or are you imagining
> somewhere else entirely?

I haven't thought about it in too much detail, but I would say
create_agg_plan() et al. I guess there's some argument to be made to do
it in setrefs.c, because we already do convert_combining_aggrefs() there
(but I don't like that much).

There's no reason to do it before we actually decided on one specific
path, so doing it earlier than create_plan() seems unnecessary. And
having it in agg specific code seems better than putting it into global
routines.

There's probably an argument for having a bit more shared code between
create_agg_plan(), create_group_plan() and
create_groupingsets_plan(). But even just adding a new extract_*_cols()
call to each of those would probably be ok.

Greetings,

Andres Freund