Subject Re: [firebird-support] When do I need descending index ?
Author Lester Caine
> Usually they are ordered ascending, but every once in a while the
> user order them descending.
> Would I then gain anything if I also have a descending index on the
> same fields ?

Depends on how often, the overhead of the second index
should not be too bad, compared with the time it takes to
sort a large table in reverse order.

Where I have given the descending option, I also have the
matching index, and switching direction is quite quick. Give
it a try without the index, then add it and see the difference.

Lester Caine
L.S.Caine Electronic Services