My impression about the one row stuff, is that there is too much special casing around it. We should somehow structure the UniqueKey data so that one row unique keys come naturally rather than special cased. E.g every column in such a case is unique in the result so create as many UniqueKeys are the number of columns
This is the beginning state of the UniqueKey, later David suggested
this as an optimization[1], I buy-in the idea and later I found it mean
more than the original one [2], so I think onerow is needed actually.
I just found I forget the links yesterday. Here is it.
