Performance trying to do a 'best match'

[jmodic]

If the digits col is used for storing the telephone number, then REVERSE KEY INDEX will help to retrive the row fast. When the user enters full digits for a telephone number, then this will work.

But why a *REVERSE KEY* index? Why not an ordinar B*Tree index? You say: "When the user enters full digits for a telephone number, then reverse key index will help to retrive the row fast". But if the same index was made as a normal one (i.e. non-reverse key), then the row retrival will be even faster, no question about that. So my question remains: Why *REVERSE KEY* index? It doesn't make sence at all in the context of the original question.