先查看存在的等待事件：

col event for a40

col WAIT_CLASS format a20

select sid,WAIT_CLASS,event,p1,p2,p3,WAIT_TIME,SECONDS_IN_WAIT from v$session_wait 

where event not like 'SQL%' and event not like 'rdbms%';

复制上面查到的等待事件，替换下面红色字体。即可找到具体的SQL语句

col objn format a26

col otype format a10

select b.* ,a.sql_fulltext from v$sqlarea a,

(select * from (select 

    count(*), 

    sql_id, 

    nvl(o.object_name,ash.current_obj#) objn,

    substr(o.object_type,0,10) otype,

    CURRENT_FILE# fn,

         CURRENT_BLOCK# blockn

   from  v$active_session_history ash

       , all_objects o

   where event like 'latch: cache buffers chains'

     and o.object_id (+)= ash.CURRENT_OBJ#

   group by sql_id, current_obj#, current_file#,

                  current_block#, o.object_name,o.object_type

   order by  count(*) desc )where rownum <=15) b

where a.sql_id=b.sql_id;

这是查看造成 

latch: cache buffers chains  等待事件的前15条记录。chak