Oracle等待事件之enq: TM – contention

sql> select   name,parameter1,parameter2,parameter3 from v$event_name where name like 'enq:   TM - contention';

NAME                           PARAMETER1           PARAMETER2           PARAMETER3

------------------------------   -------------------- -------------------- --------------------

enq: TM - contention           name|mode            object #             table/partition

SELECT distinct w.tm, w.p2 OBJECT_ID,   l.inst_id, l.sid, l.lmode, l.request,l.block

 FROM

  (   SELECT p2, p3, 'TM-'||substr(p2raw,-8)||'-'||lpad(p3,8,'0') TM

        FROM v$session_wait

       WHERE event='enq: TM - contention'

         and state='WAITING'

  )   W,

    gv$lock L

 WHERE l.type(+)='TM'

     and l.id1(+)=w.p2

     and l.id2(+)=w.p3

 ORDER BY tm, lmode desc, request desc

;

SYS@cdbtest1(CDB$ROOT)> lock table t   in exclusive mode;

Table(s) Locked.

SYS@cdbtest1(CDB$ROOT)> update t set   object_id=100 where object_id=100;

SYS@cdbtest1(CDB$ROOT)>     select inst_id, event#, event,count(*)   from gv$session

    2       where wait_class#   <> 6

    3      group by inst_id,   event#,event

    4      order by 1,4 desc;

     INST_ID     EVENT# EVENT                            COUNT(*)

---------- ----------   ------------------------------ ----------

           1        278 enq: TM -   contention                    1

           1        414 SQL*Net message to   client               1

SELECT distinct w.tm, w.p2 OBJECT_ID,   l.inst_id, l.sid, l.lmode, l.request,l.blocklmode, l.request,l.block

 FROM

    2    3    ( SELECT p2, p3,   'TM-'||substr(p2raw,-8)||'-'||lpad(p3,8,'0') TM

    4        FROM v$session_wait

    5       WHERE event='enq: TM -   contention'

    6         and state='WAITING'

    7    ) W,

    8    gv$lock L

    9   WHERE l.type(+)='TM'

 10       and l.id1(+)=w.p2

 11       and l.id2(+)=w.p3

 12     ORDER BY tm, lmode desc, request desc

 13  ;

TM                    OBJECT_ID    INST_ID        SID      LMODE      REQUEST      BLOCK

-------------------- ---------- ----------   ---------- ---------- ---------- ----------

TM-00013866-00000000      79974          1        113          6          0          1

TM-00013866-00000000      79974          1         91          0          3          0