Carsten,

> You're absolutly right.
> If i remove the f_id_auftrag + 0 the query is fast (1 sec).
> The problem is that than many other queries are slow.
> (see Message:Performance differences from 25.11.2004)
> So i really come to the conclusion that Firebird is not usable for
> reports, where the user can himself make the queries (user can pick
> fields from different tables and can combine them with 'and' or 'or')

You must be working with reports/queries of a more advanced class then
my users ... because in our system we allow users to select criteria
fields from a 'menu' of choice (in some cases with 75+ choices, from
10's of tables) and I have yet to have a user report poor performance
with a query/report (our tool is also used for users to build browse
lists to access/search for records to work on).

Sean