实验：
session 1:
SQL> show user;
USER is "SYS"
SQL>
SQL> create table t_all_objs as select owner,object_id,object_name from all_objects where 0=1;
Table created.
SQL> alter table T_ALL_OBJS add constraint pk_t_all_objs primary key (OBJECT_ID);
Table altered.
SQL> insert into t_all_objs(owner,object_id,object_name) values('TEST',2013011701,'test1');
1 row created.
SQL> insert into t_all_objs(owner,object_id,object_name) values('TEST',2013011702,'test2');
1 row created.
SQL> commit;
Commit complete.
SQL> select sid from v$mystat where rownum<2;
SID
----------
61
SQL>
SQL> select * from t_all_objs;
OWNER OBJECT_ID OBJECT_NAME
------------------------------ ---------- ------------------------------
TEST 2013011701 test1
TEST 2013011702 test2
SQL> update t_all_objs set object_name='test11' where object_id=2013011701;
1 row updated.
未提交...................................
session 2:
SQL> update t_all_objs set object_name='test101' where object_id=2013011701;
1 row updated.
hang住了...........................
--显然是有阻塞，假设我们只知道阻塞的对象是T_ALL_OBJS表，则排障如下，主要是根据将object_id关联到v$session的ROW_WAIT_OBJ#，如下：
set lines 200 pages 999
col ORACLE_USERNAME for a14
col OBJECT_NAME for a20
col MACHINE for a14
col OS_USER_NAME for a14
col terminal for a14
select l.session_id sid,
s.serial#,
l.locked_mode,
l.oracle_username,
l.os_user_name,
s.machine,
s.terminal,
o.object_name,
o.object_type,
o.object_id,
s.logon_time
from v$locked_object l, dba_objects o, v$session s
where l.object_id = o.object_id
and o.object_name='T_ALL_OBJS'
and l.session_id = s.sid
order by sid, s.serial#;
SID SERIAL# LOCKED_MODE ORACLE_USERNAM OS_USER_NAME MACHINE TERMINAL OBJECT_NAME OBJECT_TYPE OBJECT_ID LOGON_TIME
---------- ---------- ----------- -------------- -------------- -------------- -------------- -------------------- ------------------- ---------- ------------
59 165 3 SYS oracle wang pts/9 T_ALL_OBJS TABLE 89985 06-NOV-17
61 721 3 SYS oracle wang pts/8 T_ALL_OBJS TABLE 89985 06-NOV-17
或者直接查询dba_object的object_id值。。。。。。。。。。。
接着关联到ROW_WAIT_OBJ#=89985，即ROW_WAIT_OBJ#=object_id
SQL> select sid,sql_id,status,blocking_session, ROW_WAIT_OBJ#,ROW_WAIT_FILE#,ROW_WAIT_BLOCK#,ROW_WAIT_ROW# from v$session where event='enq: TX - row lock contention' and ROW_WAIT_OBJ#=89985;
SID SQL_ID STATUS BLOCKING_SESSION ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW#
---------- ------------- -------- ---------------- ------------- -------------- --------------- -------------
59 c53uad8st2u8t ACTIVE 61 89985 1 102393 0
--接着根据blocking_seesin=61，查询：
SQL> select sid,serial#,sql_id,status,event,blocking_session, ROW_WAIT_OBJ#,ROW_WAIT_FILE#,ROW_WAIT_BLOCK#,ROW_WAIT_ROW# from v$session where sid=61;
SID SERIAL# SQL_ID STATUS EVENT BLOCKING_SESSION ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW#
---------- ---------- ------------- -------- ---------------------------------------------------------------- ---------------- ------------- -------------- --------------- -------------
61 721 INACTIVE SQL*Net message from client -1 0 0 0
--找到原因sid,杀掉：
SQL> alter system kill session '61,721' immediate;
System altered.
SQL>
--发现session 2已经提交了
SQL> update t_all_objs set object_name='test101' where object_id=2013011701;
1 row updated.
--commit提交后查询
SQL> commit;
Commit complete.
SQL> select * from t_all_objs;
OWNER OBJECT_ID OBJECT_NAME
------------------------------ ---------- ------------------------------
TEST 2013011701 test101
TEST 2013011702 test2
SQL>
============================================================================================
或者直接用如下三种方法排查：
select SID,TYPE,ID1,ID2,LMODE,REQUEST,CTIME,BLOCK from V$lock where block=1 or request<>0;
SID TY ID1 ID2 LMODE REQUEST CTIME BLOCK
---------- -- ---------- ---------- ---------- ---------- ---------- ----------
59 TX 393249 10702 0 6 127 0
61 TX 393249 10702 6 0 135 1
select a.sid hold_sid, b.sid wait_sid, a.type, a.id1, a.id2, a.ctime
from v$lock a, v$lock b
where a.id1 = b.id1
and a.id2 = b.id2
and a.block = 1
and b.block = 0;
HOLD_SID WAIT_SID TY ID1 ID2 CTIME
---------- ---------- -- ---------- ---------- ----------
61 59 TX 393249 10702 108
select decode(request,0,'holder: ','waiter: ') ||
sid session_id, id1, id2, lmode, request, type
from v$lock
where (id1, id2, type) in (select id1, id2, type from v$lock where request > 0)
order by id1, request;
SESSION_ID ID1 ID2 LMODE REQUEST TY
------------------------------------------------ ---------- ---------- ---------- ---------- --
holder: 61 393249 10702 6 0 TX
waiter: 59 393249 10702 0 6 TX
0