return MAX and when it happened

Hi all,

suppose I have a table like:

CREATE TABLE mytab
(
num integer,
mydate timestamp
);

and I want to find MAX(num) and the "mydate" where it first happened.

I guess I could use

select * from mytab where num = (select MAX(num) from mytab) order by
mydate limit 1;

but that would scan the data twice (I guess...)

Do I have to write my own MAX function, something like:

select MYMAX(num, timestamp) from mytab

which would return a custom type?
Or is there a better way?