等待事件row cache lock，latch row cache objects处理过程.txt

latch:row cache objects 
row cache objects
处理过程

a:正在进行时

1判断数据库中的等待事件是否是 latch  row cache objects
select count(*), event from v$session group by event order by 1 desc; ---latch:row cache objects

2：v$session 中的p1,p2,p3 可以直接定位到 row cache object/lock 中等待的对象
select p1,p1raw,p2,p2raw from v$session where  event like '%latch  row cache objects%'

3：定位到具体是rowcache中的那个对象产生了竞争等待
SELECT kqrsttxt PARAMETER,
               -- kqrstcid CACHE#, 
              kqrstcln "Lchild#",
               kqrstgrq "DCGets",
               l.gets   "LGets",
               l.misses "Misses"
         FROM X$KQRST, V$LATCH_CHILDREN l
         WHERE l.addr = &p1
           and l.child# = KQRSTCLN
     ORDER BY 1, 2;
PARAMETER                           Lchild#     DCGets      LGets     Misses
-------------------------------- ---------- ---------- ---------- ----------
dc_rollback_segments                      1 1546954198 4095446607 2258169213

本案例（通过以上方法我们可以直接定位到dc_rollback_segments产生了竞争等待即undo段）

b:过去时

select v.P1TEXT, v.P1, v.P2TEXT, v.P2
  from v$active_session_history v
 where v.EVENT like '%row cache objects%'
 and v.SAMPLE_TIME>=to_date('2017-06-02 11:00','yyyy-mm-dd hh24:mi')
 and v.SAMPLE_TIME<=to_date('2017-06-02 12:00','yyyy-mm-dd hh24:mi')

或者

select d.P1TEXT,d.P1,d.P2TEXT,d.P2 from dba_hist_active_sess_history d
 where d.EVENT like '%row cache objects%'
 and d.SAMPLE_TIME>=to_date('2017-06-02 11:00','yyyy-mm-dd hh24:mi')
 and d.SAMPLE_TIME<=to_date('2017-06-02 12:00','yyyy-mm-dd hh24:mi')
-------------------------------------------------------------
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
address 107322559952 number 411
.......

因为是过去时刻，此时的p1已经被转换成10进制，需要我们重新转换成16进制
select upper(to_char(107322559952,'xxxxxxxxxxxxxxxx')) from dual;
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