Oracle 키값 설정이 안되어 있을시 중복행 제거

왜이리 이런 일이 많이 발생하냐....ㅠ.ㅠ

DELETE FROM table
 WHERE ROWID IN
             (SELECT RID FROM
                           (SELECT ROWID RID,ROW_NUMBER()
                                         OVER(PARTITION BY key1,key2.... ORDER BY ROWID) RN
                                FROM table
                           )
                WHERE RN<>1
             );