the reason for preaggregating is because there's too much data to fit into excel and growing. But, in preaggregating the column names need to remain intact, with no intersection of time dimension with fact columns. No intersection means only grouping, so that there are fewer rows to import. It would work, if only I didn't need to divide sum(lineItems) by DISTINCT invoices for AVG metric...

I really wish I could just import all the data and let Excel do the pivoting for me.

I shared Excel spreadsheet.