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;