Re: [HACKERS] WIP: Aggregation push-down

Antonin Houska <ah(at)cybertec(dot)at> wrote:

> I've reworked the patch so that separate RelOptInfo is used for grouped
> relation. The attached patch is only the core part. Neither postgres_fdw
> changes nor the part that tries to avoid the final aggregation is included
> here. I'll add these when the patch does not seem to need another major rework.

This is the next version. After having posted a few notes to the [1] thread,
I'm returning to the original one so it can be referenced from my entry in the
CF application. As proposed in the other thread, it uses only "simple
aggregation". The 2-stage aggregation, which gives more power to the feature
and which also enables paralle processing for it, will be coded in a separate
patch.

I eventually decided abandon the Var substitution proposed by Heikki in
[2]. It's not necessary if we accept the restriction that the feature accepts
only simple column reference as grouping expression so far.

[1] https://www.postgresql.org/message-id/c165b72e-8dbb-2a24-291f-113aeb67b76a%40iki.fi

[2] https://www.postgresql.org/message-id/113e9594-7c08-0f1f-ad15-41773b56a86b%40iki.fi

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