I wonder how much back-compatibility and dump reloading problems this
might cause? :(
Tom Lane wrote:
> Log Message:
> -----------
> Make the behavior of HAVING without GROUP BY conform to the SQL spec.
> Formerly, if such a clause contained no aggregate functions we mistakenly
> treated it as equivalent to WHERE. Per spec it must cause the query to
> be treated as a grouped query of a single group, the same as appearance
> of aggregate functions would do. Also, the HAVING filter must execute
> after aggregate function computation even if it itself contains no
> aggregate functions.
