> If a user supply a filter condition that returns 2 million rows and want
> this result ordered, I don't know how you can prevent :)

you understand my problem :)

> But, how much time would take to do a "select count(*) from Bla where
> SearchCondition" if the SearchCondition is not restrictive enough ?

more than the 100 ms that is a requierement for us :( unfortunatly in firebird the count(*) is what is the most slower :(

> Another option, Can you try to not order on the server side, and fetch
> the results to the client, and if you reach a given limit (for example >
> 10000), sugest the user to try a more restrictive filter condition, or
> have patience to wait for the sorting, if the user insist in return a
> LOT of records, he must accept to wait for the sorting on the client side.

in fact it's an web application, we can not do like this :( and anyway i don't want that a single user use too much of server resource because he want to sort 2 000 000 rows !

thanks for all
stephane