Re: Query Optimiser

John B writes: |Has anyone noticed the 5.X optimizer making bad choices when |choosing a query plan? choosing a query plan? In my case the |optimizer insists in performing a sequential read of a detail table |ignoring the unique index used to join to the master. Performance, |as you can imagine is very, very poor. |Informix has not given us information as to whether this is a known |bug, but they seemed supprised. I've seen it in several different |forms over the last month or so, and I wonder how many other people |have the same experience... We have had some experience with queries working okay under 4.X Online and suddenly becoming disastrously slow under 5.X, for these reasons. Usually, however, we have checked the code and discovered that if you re-arrange it more logically, the optimizer decides to use the index. Hope this helps, Richard Ridley