oracle如何慢查询？

select *

 from (select s.SQL_TEXT,

        s.EXECUTIONS "执行次数",

        s.PARSING_USER_ID "用户名",

        rank() over(order by EXECUTIONS desc) EXEC_RANK

     from v$sql s

     left join all_users u

      on u.USER_ID = s.PARSING_USER_ID) t

 where exec_rank <= 100;