Today the aggregation window functions only support RANGE type window frames with the default frame boundaries (UNBOUNDED PRECEDING and UNBOUNDED FOLLOWING/CURRENT ROW depending on the existence of ORDER BY in the OVER clause). ROWS support exists for the ROW_NUMBER window function (this doesn't support RANGE type at all). We should add support for ROWS type frames for the aggregation window functions as well. For now we will do this for the default frame boundaries since sliding window support hasn't been added yet.

I'll be working on this change, please assign it to me

cc @siddharthteotia @walterddr @Jackie-Jiang