> Anyways, is it possible to have both, an ascending and a descending
> index on the same column? Will disk storage for these indexes
> duplicate?

Just to sum up:
- ASCending index can be used to find MIN(), or to ORDER BY (ASC)
- DESCending index can be used to find MAX(), or to ORDER BY DESC
- WHERE clause can use either of these indexes, but if you have two similar indexes
that differ just by ASC/DESC direction, optimizer sometimes incorrectly use both.

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