>

index on cfield1+dtos(dfield2) tag tag2

>
>Creating an index tag containing more than one field does not help for Rushmore purposes. If you need to run queries that involve these fields in the WHERE clause, you need an index on each indivual field for Rushmore to kick in (with regards to those fields).

Are you sure about that? I believe that if you use the exact index expression in the WHERE you get full optimization.