If Kozz cannot upgrade to PostgreSQL for some reason couldn't Kozz ape a subselect with by creating a tempory table "ttable" and then join "atable" with that? sonething like this ...

create table ttable as  
   SELECT doc_num, MAX(version) FROM atable GROUP BY doc_num;

SELECT title, doc_num, version
  FROM atable a, ttable t
  WHERE  a.doc_num = t.doc_num and a.version = t.version;
[download]

... I don't know about the other monks I find SQL
fun like its a weird puzzle.