Re: We are not following the spec for HAVING without GROUP BY

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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