Re: A problem about partitionwise join

Hi Alvaro,

Thank you for reviewing this patch.

On Wed, Sep 11, 2019 at 4:48 AM Alvaro Herrera from 2ndQuadrant <
alvherre(at)alvh(dot)no-ip(dot)org> wrote:

> So in this patch, the input restrictlist is modified to include the
> clauses generated by generate_join_implied_equalities_for_all. That
> doesn't seem okay -- doesn't it affect downstream usage of the
> restrictlist in the caller of set_joinrel_size_estimates?
>

Actually the joinclauses generated by
generate_join_implied_equalities_for_all only affects the restrictlist
used in have_partkey_equi_join to check equi-join conditions for
partition keys. The input restrictlist would not be altered.

>
> I wonder if it's possible to do this by using the ECs directly in
> have_partkey_equi_join instead of using them to create fake join
> clauses.
>

Hmm.. I thought about this option and at last figured that what we need
to do in have_partkey_equi_join with the ECs is actually the same as in
generate_join_implied_equalities_for_all. Maybe I didn't think it
correctly.

Thanks
Richard