Re: Push down Aggregates below joins

Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:

> On 06/20/2018 10:12 PM, Heikki Linnakangas wrote:
> > Currently, the planner always first decides the scan/join order, and
> > adds Group/Agg nodes on top of the joins. Sometimes it would be legal,
> > and beneficial, to perform the aggregation below a join. I've been
> > hacking on a patch to allow that.
> >
>
> There was a patch [1] from Antonin Houska aiming to achieve something
> similar. IIRC it aimed to push the aggregate down in more cases,
> leveraging the partial aggregation stuff.

Yes, I interrupted the work when it become clear that it doesn't find its way
into v11. I'm about to get back to it next week, and at least rebase it so it
can be applied to the current master branch.

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26, A-2700 Wiener Neustadt
Web: https://www.cybertec-postgresql.com