Re: Aggregate ORDER BY patch

>>>>> "Heikki" == Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
>> No artificial restrictions are imposed on what syntactical>> combinations are allowed. However, ORDER BY is not
allowedwith>> aggregates used as window functions (as per the existing>> restriction on DISTINCT).
 
Heikki> How is this different from window functions?

Window functions return a row for each row of input, aggregates don't.

The reason I didn't tackle the case of aggregate functions used as
window functions is that the spec allows constructs like this:

array_agg(a order by b) over (order by c)

which can't be represented using the aggregate-as-window-function
mechanism as it currently stands, since you'd have to re-sort the
window each time.

-- 
Andrew (irc:RhodiumToad)