On Mon, Dec 5, 2016 at 7:02 PM, Corey Huinker <corey.huin...@gmail.com> wrote:
> >> Would it be worth replacing the condition with the equivalent? >> I mean would that help optimizing better some queries when it knows that >> a is (not) nullable or when "a" is more complicated expression? >> >> a <> a : (a IS NULL) AND NULL >> a = a : (a IS NOT NULL) OR NULL >> > > > I think you're looking for > > a IS DISTINCT FROM a > > > And that will work for cases where a might be null. > > I have no opinion about whether adding such a test to the planner is worth > it. > No, (a IS DISTINCT FROM a) will evaluate to FALSE when a is NULL. The other conditions (a <> a) , ((a IS NULL) AND NULL) will evaluate to NULL.
