On Sat, Oct 03, 2009 at 01:05:49PM -0400, Tom Lane wrote: > What you might be after is something like Postgres' DISTINCT ON > feature Yup, looks that way to me as well. > I have never really played around with this aspect of MySQL ... Me neither. > but looking at this example, and presuming that you find that > it actually does something useful, I wonder whether they interpret > the combination of GROUP BY and ambiguous-per-spec ORDER BY > in some fashion similar to DISTINCT ON. Yup, does look that way doesn't it. It's still a weird pair of semantics to conflate. Hum, if they were assuming that you'd always have to implement GROUP BY by doing a sort step first then I can see why they'd end up with this. But if you want to do *anything* else (i.e. hash aggregate in PG) then you want to keep the semantics of GROUP BY and ORDER BY separate as the spec and indeed PG does. -- Sam http://samason.me.uk/ -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
