Paolo,
you could try

delete from mytable
where exists(select 1 from listtable where listtable.id = mytable.id)

Though Arno recently replied that this in theory should be the same as what
you are currently using.

Report back to us your result,
Set

At 16:36 20.03.2003 +0100, you wrote:

>I have a query like this:
>
>delete from mytable where mytable.id in ( select id from listtable where
><search condition> )
>
>Usually this query delete only few record from a large table. It works, but
>slowly, because FB doesn't use the index on mytable.id.
>
>How can I spedd up this query ?