Re: Making Vars outer-join aware

Thanks for the work! I have a question about qual clause placement.

For the query in the example

    SELECT * FROM t1 LEFT JOIN t2 ON (t1.x = t2.y) WHERE foo(t2.z)

(foo() is not strict.) We want to avoid pushing foo(t2.z) down to the t2
scan level. Previously we do that with check_outerjoin_delay() by
scanning all the outer joins below and check if the qual references any
nullable rels of the OJ, and if so include the OJ's rels into the qual.
So as a result we'd get that foo(t2.z) is referencing t1 and t2, and
we'd put the qual into the join lists of t1 and t2.

Now there is the 'varnullingrels' marker in the t2.z, which is the LEFT
JOIN below (with RTI 3). So we consider the qual is referencing RTE 2
(which is t2) and RTE 3 (which is the OJ). Do we still need to include
RTE 1, i.e. t1 into the qual's required relids? How should we do that?

Thanks
Richard