Re: Aggregate Push Down - Performing aggregation on foreign server

2016-08-31 10:03 GMT+02:00 Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>:

> On 2016/08/31 16:42, Pavel Stehule wrote:
> > 2016-08-31 9:00 GMT+02:00 Robert Haas <robertmhaas(at)gmail(dot)com>:
> >
> >> On Wed, Aug 31, 2016 at 11:56 AM, Pavel Stehule <
> pavel(dot)stehule(at)gmail(dot)com>
> >> wrote:
> >>> It is pity - lot of performance issues are related to this missing
> >> feature.
> >>
> >> I don't think you are being very clear about what feature you are
> >> talking about. The feature that Jeevan has implemented is pushing
> >> aggregates to the remote side when postgres_fdw is in use. The
> >> feature you are talking about is evidently something else, but you
> >> haven't really said what it is. Or not in a way that I can
> >> understand.
> >>
> >
> > yes, It is not clear if FDW aggregate push down can be implemented
> together
> > with internal aggregate push down. Aggregate push down ~ try to aggregate
> > first when it is possible
>
> What do you mean by "internal aggregate push down"? Partition-wise
> aggregation? Aggregate/group by before join (something like [1])? IIUC,
> what Jeevan proposes in this thread is to implement the aggregate push
> down API that is specific to FDWs in postgres_fdw. Any other push down
> work would need to use different APIs and would need to separately
> proposed/discussed.
>

ok I understand now.

Regards

Pavel

>
> Thanks,
> Amit
>
> [1]
> https://www.postgresql.org/message-id/CAKJS1f9kw95K2pnCKAoPmNw==
> 7fgjSjC-82cy1RB+-x-Jz0QHA(at)mail(dot)gmail(dot)com
>
>
>