Group by -- precedence question

begin;
create table f (v numeric);
insert into f values (1), (0.8);
select ceil(v) as v from f group by v;

-- sorta expected the result to be grouped by the column alias,
-- not by the in the table

v
───
1
1

This is the correct behavior, right? To group by the column alias, I'd have
to use "group by 1" or use a different name, right?