Re: Aggregate Push Down - Performing aggregation on foreign server

On Tue, Aug 30, 2016 at 6:51 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
wrote:

> Hi
>
> 2016-08-30 15:02 GMT+02:00 Jeevan Chalke <jeevan(dot)chalke(at)enterprisedb(dot)com>:
>
>> Hi all,
>>
>> Attached is the patch which adds support to push down aggregation and
>> grouping
>> to the foreign server for postgres_fdw. Performing aggregation on foreign
>> server results into fetching fewer rows from foreign side as compared to
>> fetching all the rows and aggregating/grouping locally. Performing
>> grouping on
>> foreign server may use indexes if available. So pushing down aggregates/
>> grouping on foreign server performs better than doing that locally.
>> (Attached
>> EXPLAIN output for few simple grouping queries, with and without push
>> down).
>>
>
> is it work without FDW too?. It can be pretty interesting too.
>

No. Aggrgate push down is supported through the GetForeignUpperPaths() hook
added for postgres_fdw. Thus it works only with postgres_fdw.

Do you mean whether this works with any extensions via implementing
create_upper_paths_hook() function?
The answer is No. This patch does not touch this hook.

>
> Regards
>
> Pavel
>
>
>>
>>
>

Thanks
--
Jeevan B Chalke
Principal Software Engineer, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company