Tom Lane <tgl@sss.pgh.pa.us> writes:
> In particular this whole business of "moving HAVING into WHERE" is
> wrong and should go away.
It sort of seems like "select aggregate(col) from tab" with no GROUP BY clause
is a bit of a special case. The consistent thing to do would be to return no
records. It's only due to the special case that SQL returns a single record
for this case.
It seems like this special case is the only way to expose this difference
between a WHERE clause and a HAVING clause with an aggregate-free expression.
It seems like all that's needed is a simple flag on the Aggregate node that
says whether to output a single record if there are no input records or to
output no records.
--
greg
