On Fri, Nov 13, 2009 at 5:09 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Quite. This is another instance of the thing I complained of before,
> that the SQL committee likes to define the behavior of specific
> aggregates instead of inducing a generic aggregate-behavior definition.
I think this makes sense from the point of view of the spec authors.
They're trying to standardize the behaviour of the functions that
their existing implementations provide without creating extra demands
on themselves to implement new features. Even if some of them do
implement more general solutions the path of least resistance to
getting their syntax standardized will be the one which imposes the
least cost on the other members of the committee.
> So we're on our own to extract one, and this proposal seems pretty
> reasonable to me: it's useful and it's consistent with the query-level
> behavior of DISTINCT and ORDER BY.
++
--
greg