Aggregation push down, reorder of join and group by

Hi,

On 2016/10/05 14:19, Chenxi Li wrote:

Hello,

I'm reading some papers about aggregation push down like in "
https://ub-madoc.bib.uni-mannheim.de/37228/1/main.pdf" and "
http://www.vldb.org/conf/1995/P345.PDF". I think it is very useful but very
complex to implement. In some complex queries, it can be a lot faster. Is
there any plan to do this in the future?

Thanks for the links. On a quick look, I think you are referring to the
following section in the document at the first link (and the title of the
paper at the second link):

4.2 Applying Eager Aggregation

I think someone is working on something like that. Check out the
following discussion (currently inactive though):

* Partial Aggregation / GROUP BY before JOIN *
/messages/by-id/CAKJS1f9kw95K2pnCKAoPmNw==7fgjSjC-82cy1RB+-x-Jz0QHA@mail.gmail.com

There is also related work which is under active development:

* Aggregate Push Down - Performing aggregation on foreign server *
/messages/by-id/CAM2+6=W=r_vh2gpccPJ4tc=+hFm4UGQsQdZgt4GiBMYVEk+5vg@mail.gmail.com

In this case, the aggregation step is pushed all the way to the remote
server where the data resides. It stands to avoid a good deal of
unnecessary data traffic across the network.

Thanks,
Amit

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