On Mon, Apr 18, 2011 at 7:13 PM, Uwe Bartels <uwe.bartels@xxxxxxxxx> wrote: > the aggregate function I was talking about is the function I need to use for > the non-group by columns like min() in my example. > There are of course several function to choose from, and I wanted to know > which causes as less as possible resources. If you do not care about the output of the non key columns, why do you include them in the query at all? That would certainly be the cheapest option. If you need _any_ column value you can use a constant. rklemme=> select * from t1; k | v ---+--- 0 | 0 0 | 1 1 | 2 1 | 3 2 | 4 2 | 5 3 | 6 3 | 7 4 | 8 4 | 9 (10 rows) rklemme=> select k, 99 as v from t1 group by k order by k; k | v ---+---- 0 | 99 1 | 99 2 | 99 3 | 99 4 | 99 (5 rows) rklemme=> Greetings from Paderborn robert -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/ -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
