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From: Richard Guo <guofenglinux@gmail.com>
Date: Wed, 25 Sep 2024 14:55:00 +0800
Message-ID: <CAMbWs49g0Oz5ws2qXxr-M2G1cw2QLQFBhuRn=YmXMGSjy4d-ZA@mail.gmail.com>
Subject: Re: Eager aggregation, take 3
To: Tender Wang <tndrwang@gmail.com>
Cc: Paul George <p.a.george19@gmail.com>, Andy Fan <zhihuifan1213@163.com>, 
	PostgreSQL-development <pgsql-hackers@postgresql.org>, pgsql-hackers@lists.postgresql.org, 
	Robert Haas <robertmhaas@gmail.com>
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On Thu, Sep 5, 2024 at 9:40=E2=80=AFAM Tender Wang <tndrwang@gmail.com> wro=
te:
> 1.  in setup_eager_aggregation(), before calling create_agg_clause_infos(=
), it does
> some checks if eager aggregation is available. Can we move those checks i=
nto a function,
> for example, can_eager_agg(), like can_partial_agg() does?

We can do this, but I'm not sure this would be better.

> 2.  I found that outside of joinrel.c we all use IS_DUMMY_REL,  but in jo=
inrel.c, Tom always uses
> is_dummy_rel(). Other commiters use IS_DUMMY_REL.

They are essentially the same: IS_DUMMY_REL() is a macro that wraps
is_dummy_rel().  I think they are interchangeable, and I don=E2=80=99t have=
 a
preference for which one is better.

> 3.  The attached patch does not consider FDW when creating a path for gro=
uped_rel or grouped_join.
> Do we need to think about FDW?

We may add support for foreign relations in the future, but for now, I
think we'd better not expand the scope too much until we ensure that
everything is working correctly.

Thanks
Richard