Re: Eager aggregation, take 3

On Thu, Sep 5, 2024 at 9:40 AM Tender Wang <tndrwang@gmail.com> wrote:
> 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 into 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 joinrel.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’t have a
preference for which one is better.

> 3.  The attached patch does not consider FDW when creating a path for grouped_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