Проблема в
WINDOW w as (ORDER BY exp desc )
Интуитивно исправил запрос на
CREATE VIEW rankers AS
SELECT charId,
char_name,
exp,
base_class as class,
race,
clanid,
rank() over(ORDER BY exp desc) as 'rank'
from characters
where level >= 76
AND ( base_class BETWEEN 88 AND 118 OR base_class IN...