>>>>> "Tom" == Tom Lane <t...@sss.pgh.pa.us> writes:
>> Query-level DISTINCT shouldn't allow columns in the order by that >> aren't in the select list because those columns _do not exist_ at >> the point that ordering logically takes place (even though in the >> implementation, they might). >> This isn't the case for aggregate order by. Tom> I entirely disagree. Why should the semantics of this Tom> combination of ORDER BY and DISTINCT be different from what they Tom> are at the query top level? We made other decisions about this Tom> feature on the basis of making the two cases work alike, and I Tom> don't think you've made an adequate argument for making them act Tom> differently. A case could possibly be made that the behaviour of DISTINCT at top level is wrong, or at least less useful than need be. Notice that there are cases where agg(distinct x order by x) is nondeterministic while agg(distinct x order by x,y) is deterministic. In my view that alone is a good argument for allowing it. -- Andrew (irc:RhodiumToad) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
