Matthew Wakeling wrote on 10.08.2010 18:03:
On Tue, 10 Aug 2010, Thomas Kellerer wrote:
No. It's built in (8.4) and it's called Windowing functions:
http://www.postgresql.org/docs/8.4/static/tutorial-window.html
http://www.postgresql.org/docs/8.4/static/functions-window.html
SELECT group, last_value(value) over(ORDER BY number)
FROM table
I may be mistaken, but as I understand it, a windowing function doesn't
reduce the number of rows in the results?
Yes you are right, a bit too quick on my side ;)
But this might be what you are after then:
select group_, value_
from (
select group_, value_, number_, row_number() over (partition by group_ order by value_ desc) as row_num
from numbers
) t
where row_num = 1
order by group_ desc
--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance
