--- In firebird-support@yahoogroups.com, Hannes Streicher
<hstreicher@...> wrote:

>
> Hello Martijn Tonies,
> >> So I wonder if this is the right approach. I tried to put indexes on
> >> some fields like AUTHOR and TITLE, but I think the use of UPPER

in the

> >> ON-clause prevents using these indexes.
>
> > That is correct, UPPER removes the ability to use an index. In
> > Firebird 2, you could use expression based indices, in Firebird
> > 1.5 or lower, I suggest you add a shadow field, eg: TITLE_UPPER,
> > which you populate by using a before insert/update trigger and
> > use that to do your compare... Considering the number of books
> > with the same title, this should be quick quicker.
>
> How about an index on a computed field ?

This is not possible from any release version of Firebird (but you
could do it like that in the future with Firebird 2)

Adam