> From: Thomas Miller
> The guy created a third column and added column 1 and column 2.
>
> By using the third column, he found a considerable performance boast
> versus using indexes on Column 1 and 2, or a combination index
> that included both.

Yes, this was already written in the message from b.p.i.sql, but ...
what conclusion could you make of it ? That replacing compound index
by index on single concatenated column will make your queries 500 times faster ?
I am not saying it is/is not true/possible, just that there are not enough informations.
How can you tell that the speed difference was caused by "more efficient indexes",
and not just different plans ?
I would not make any judgements without more testing, comparing plans/statistics etc.

Ivan
http://www.volny.cz/iprenosil/interbase