Subject Re: [firebird-support] FB 2.0 / FB1.5 optimizer difference
Author Dmitry Yemanov
Hans wrote:
> All I have been able to find on page 62 is
> 'More Optimization of NOT Conditions'
> 'NOT conditions are simplified and optimized via an index when possible'

Sorry, this is my fault. It's on page 102, but only the ALL predicate is
mentioned there. The fact that NOT IN is equal to <> ALL is implied, but
it's not very obvious for everybody.

v2.0 de-optimizes both ALL and NOT IN subqueries in order to guarantee a
consistent result.