Is there anything in the works to enable local computation of totals for relational datasources?
Looking at the guide below, it's clearly possible in multidimensional datasources to define how totals are calculated:
We have a case where we want to sum the ratios generated from a calculated field. The problem is that the Grand Total uses the formula the calculated field and provides the ratio result using the other totals. We'd like, in this case, to specify that we want this field's Grand Total to be a sum of the ratios as opposed to a calculation.
I've run into a similar problem before.
I am not positive it will work for what you are describing, but you may find this write-up by Jonathan Drummey helpful.