/*
 * FUNCTIONAL TESTS
 */
create extension if not exists argm;
create table tbl as 
select d,
	i,
	grp::text || '-' || d || '-' || repeat(i::text, 10) txt,
	grp
from (
	select date'2011-11-11' - generate_series(1, 8) d,
		generate_series(1, 9) i
	order by random()
) _
cross join (values
	(1),
	(2),
	(3)
) grp (grp);
analyze tbl;
select grp, argmax(txt, i, d), argmin(array[txt], (i, d)) from tbl group by grp order by grp;
 grp |         argmax          |          argmin           
-----+-------------------------+---------------------------
   1 | 1-11-10-2011-9999999999 | {1-11-03-2011-1111111111}
   2 | 2-11-10-2011-9999999999 | {2-11-03-2011-1111111111}
   3 | 3-11-10-2011-9999999999 | {3-11-03-2011-1111111111}
(3 rows)