Re: A problem about join ordering

Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> I'm wondering whether we need to insist on being strict for the lower
> OJ's min_righthand. What if we instead check strictness for its whole
> syn_righthand?

Surely not. What if the only point of strictness is for a rel that
isn't part of the min_righthand? Then we could end up re-ordering
based on a condition that isn't actually strict for what we've
chosen as the join's RHS.

It might be possible to change the other part of the equation and
consider the A/B join's min_righthand instead of syn_righthand
while checking if Pcd uses A/B's RHS; but I'm not real sure about
that either.

regards, tom lane