Re: Making Vars outer-join aware

Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> On Sun, Aug 21, 2022 at 6:52 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> What I'm thinking we should do about this, once we detect that
>> this identity is applicable, is to generate *both* forms of Pbc,
>> either adding or removing the varnullingrels bits depending on
>> which form we got from the parser.

> Do you mean we generate two RestrictInfos for Pbc in the case of
> identity 3, one with varnullingrels and one without varnullingrels, and
> choose the appropriate one when forming join paths?

Right.

> Do we need to also
> generate two SpecialJoinInfos for the B/C join in the first order, with
> and without the A/B join in its min_lefthand?

No, the SpecialJoinInfos would stay as they are now. It's already the
case that the first join's min_righthand would contain only B, and
the second one's min_righthand would contain only C.

regards, tom lane