Descending indexes in 10g

How significant are descending indexes in 10gr2? If you have an ascending index on something can it still be used for descending sorts?

e.g. if you want to do
ORDER BY a,b DESC, c
do you need an index on
a, b DESC, c
or is one on
a,b,c
enough?

If the answer is that you do need the DESC index column, how would you get that into a primary key?

Thanks

Andy Kent Received on Thu May 25 2006 - 05:10:26 CDT