Re: Partition-wise aggregation/grouping

The promised new version of my patch is here:

https://www.postgresql.org/message-id/9666.1491295317%40localhost

Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:

> On Tue, Mar 21, 2017 at 1:47 PM, Antonin Houska <ah(at)cybertec(dot)at> wrote:
>
> Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com> wrote:
>
> IIUC, it seems that you are trying to push down the aggregation into the
> joining relations. So basically you are converting
> Agg -> Join -> {scan1, scan2} into
> FinalAgg -> Join -> {PartialAgg -> scan1, PartialAgg -> scan2}.
> In addition to that your patch pushes aggregates on base rel to its children,
> if any.
>
> Where as what I propose here is pushing down aggregation below the append
> node keeping join/scan as is. So basically I am converting
> Agg -> Append-> Join -> {scan1, scan2} into
> Append -> Agg -> Join -> {scan1, scan2}.
> This will require partition-wise join as posted in [1].
> But I am planning to make this work for partitioned relations and not for
> generic inheritance.
>
> I treat these two as separate strategies/paths to be consider while planning.
>
> Our work will overlap when we are pushing down the aggregate on partitioned
> base relation to its children/partitions.
>
> I think you should continue working on pushing down aggregate onto the
> joins/scans where as I will continue my work on pushing down aggregates to
> partitions (joins as well as single table). Once we are done with these task,
> then we may need to find a way to integrate them.
>
> [1] https://www.postgresql.org/message-id/flat/CAFjFpRfQ8GrQvzp3jA2wnLqrHmaXna-urjm_UY9BqXj=EaDTSA(at)mail(dot)gmail(dot)com#CAFjFpRfQ8GrQvzp3jA2wnLqrHmaXna-urjm_UY9BqXj=EaDTSA@mail.gmail.com

My patch does also create (partial) aggregation paths below the Append node,
but only expects SeqScan as input. Please check if you patch can be based on
this or if there's any conflict.

(I'll probably be unable to respond before Monday 04/17.)

--
Antonin Houska
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de, http://www.cybertec.at