Re: Allowing NOT IN to use ANTI joins

On 15 July 2014 12:58, David Rowley <dgrowleyml@gmail.com> wrote:

> I found that the call to is_NOTANY_compatible_with_antijoin adds about 0.2%
> and 2.3% to total planning time. Though the 2.3% was quite an extreme case,
> and the 0.2% was the most simple case I could think of.

I think its quite important that we don't apply every single
optimization we can think of in all cases. Fast planning of short
requests is as important as good planning of longer requests.

Is there a way we can only run this extra test when we have reasonable
idea that there is potential to save significant costs? Or put another
way, can we look at ways to skip the test if its not likely to add
value. Obviously, if we have a good feeling that we might save lots of
execution time then any additional planning time is easier to justify.

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services