On Wed, 27 Feb 2019 at 13:41, Li, Zheng <zhelli@amazon.com> wrote:
> We still check for inner side's nullability, when it is nullable we
> append a "var is NULL" to the anti join condition. So every outer
> tuple is going to evaluate to true on the join condition when there
> is indeed a null entry in the inner.
That's possible, at least providing the var is NULL is an OR
condition, but the problem there is that you force the plan into a
nested loop join. That's unfortunately not going to perform very well
when the number of rows to process is large.
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
