Mike,

>I'm not sure what kind of queries you're building, but I seldom have a query that the user doesn't have the potential of passing only one of a set of parameters. If the user enters only one parameter and there's no index, well you know what happens then. Unless I'm misunderstanding you, testing all combinations of the parameters and indexes sounds wasteful.

Well In my case the kind of possible queries are mostly determined by me, the developer. If a user builds a query and can't be optimized, well the user has to wait a little longer for his/her result.

A general rule I use is that the index ** MUST have a HIGH SELECTIVITY **. It makes no sense to index logical fields if the balance is somewhere between 80-20 and 20-80 (.T. or .F.), the burden could be higher than the benefit. I always try to imagine which kind of queries are frequent within a application, then try to determin which indexes would be usefull. For infrequent or occasional queries I do not reserve indexes.

But if I did misjudge the situation and users complain about performance, I always can add another index.

We both have different standpoints: I don't use indexes unless I really need them, keeping the performance for the most common use of the applic optimized. You add indexes because you think it might be handy and could increase performance for certain queries, but might be pulling down performance for the rest the application.

Walter,