Magnus,

>is it possible to go PLAN(all_relevant_tables natural) or something? ;-)

I hope not! Normally, you would want to use some indexes - though not
necessarily all suggested by the "optimizer". Maybe you can show us some of
your real SQL, together with the chosen plan and a short description of the
tables/views involved (e.g. does each table contain 10 or 10 million
records) and available indexes?

>Where can I find more detailed descriptions of PLAN than those in the
>Language Reference?

Trial and error is the best I've come up with (though a better one may well
exist). Write statements in IB_SQL (www.ibobjects.com), prepare them,
investigate the plan and see if you think you can improve something.

Set