KaiGai, David Rowley and myself have all made mention of various ways we could optimize aggregates.
Following WIP patch adds an extra function called a "combining function", that is intended to allow the user to specify a semantically correct way of breaking down an aggregate into multiple steps.
Gents, is this what you were thinking? If not...
A quick look at the patch makes me assume that the patch does not handle the problem of combining transvals or move at all in that direction (which is fine, just reconfirming).
So, essentially, we are adding a "grand total" on top of individual sum() or count() operations,right?
Also, should we not have a sanity check for the user function provided?