> 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
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L.S.Caine Electronic Services