在使用v$session视图在查询会话的行锁的等待事件时，视图中提供了会话等待的对象号(ROW_WAIT_OBJ#)、文件号(ROW_WAIT_FILE#)、块号(ROW_WAIT_BLOCK#)和行号(ROW_WAIT_ROW#)但是如何使用这些信息定位出会话等待的是哪一行呢？答案就是使用DBMS_ROWID
打开两个会话同时更新同一条数据
#session 1
zx@ORCL>select distinct sid from v$mystat;
SID
----------
22
zx@ORCL>
zx@ORCL>update zx set name='zx' where id=1;
1 row updated.
#session 2
zx@ORCL>select distinct sid from v$mystat;
SID
----------
145
zx@ORCL>update zx set name='zx' where id=1;
此时session2会被session1阻塞，查询v$session会话145在等待enq: TX - row lock contention
zx@ORCL>col event for a40
zx@ORCL>select SID,EVENT,ROW_WAIT_OBJ#,ROW_WAIT_FILE#,ROW_WAIT_BLOCK#,ROW_WAIT_ROW# from v$session where sid=145;
SID EVENT ROW_WAIT_OBJ# ROW_WAIT_FILE# ROW_WAIT_BLOCK# ROW_WAIT_ROW#
---------- ---------------------------------------- ------------- -------------- --------------- -------------
145 enq: TX - row lock contention 99754 18 15571 7
查询v$lock确认会话145在请求会话22的TX锁
zx@ORCL>select sid,type,id1,id2,lmode,request from v$lock where sid=145 or sid=22 order by 1;
SID TYPE ID1 ID2 LMODE REQUEST
---------- ------ ---------- ---------- ---------- ----------
22 AE 100 0 4 0
22 TM 99754 0 3 0
22 TX 4390915 581 6 0
145 TM 99754 0 3 0
145 TX 4390915 581 0 6
145 AE 100 0 4 0
使用如下语句查询会话145等待哪个表的哪个行
zx@ORCL>col owner for a10
zx@ORCL>col object_name for a10
zx@ORCL>col rowid for a30
zx@ORCL>select b.owner,b.object_name,dbms_rowid.rowid_create(1,s.ROW_WAIT_OBJ#,s.ROW_WAIT_FILE#,s.ROW_WAIT_BLOCK#,ROW_WAIT_ROW#) "rowid" from v$session s,dba_objects b where s.ROW_WAIT_OBJ#=b.object_id and s.si
d=145;
OWNER OBJECT_NAM rowid
---------- ---------- ------------------------------
ZX ZX AAAYWqAASAAADzTAAH
--使用上面查询出的rowid查看数据，即为session2等待的行
zx@ORCL>select * from zx.zx where rowid='AAAYWqAASAAADzTAAH';
ID NAME
---------- ------------------------------
1 ZX
官方文档：http://docs.oracle.com/cd/E11882_01/appdev.112/e40758/d_rowid.htm#ARPLS053
使用下面语句查找会话之间的阻塞关系
SELECT ('节点' || a.inst_id || ' session ' || a.sid || ',' || a_s.serial# ||
'阻塞了节点' || b.inst_id || ' session ' || b.sid || ',' || b_s.serial#) blockinfo,
a.inst_id,
a_s.sid,
a_s.schemaname,
a_s.module,
a_s.status,
a_s.event,
a.type lock_type,
a.id1,
a.id2,
decode(a.lmode,
0,
'none',
1,
NULL,
2,
'row-S(SS)',
3,
'row-X(SX)',
4,
'share(S)',
5,
'S/Row-X(SSX)',
6,
'exclusive(X)') lock_mode,
a.ctime time_hold,
'后为被阻塞信息' remark_flag,
b.inst_id blocked_inst_id,
b.sid blocked_sid,
b.type blocked_lock_type,
decode(b.request,
0,
'none',
1,
NULL,
2,
'row-S(SS)',
3,
'row-X(SX)',
4,
'share(S)',
5,
'S/Row-X(SSX)',
6,
'exclusive(X)') blocked_lock_request,
b.ctime time_wait,
b_s.schemaname blocked_schemaname,
b_s.module blocked_module,
b_s.status blocked_status,
b_s.sql_id blocked_sql_id,
b_s.event,
obj.owner blocked_owner,
obj.object_name blocked_name,
obj.object_type blocked_object_type,
CASE
WHEN b_s.row_wait_obj# <> -1 THEN
dbms_rowid.rowid_create(1,
obj.data_object_id,
b_s.row_wait_file#,
b_s.row_wait_block#,
b_s.row_wait_row#)
ELSE
'-1'
END blocked_rowid, --被阻塞数据的rowid
decode(obj.object_type,
'TABLE',
'select * from ' || obj.owner || '.' || obj.object_name ||
' where rowid=''' ||
dbms_rowid.rowid_create(1,
obj.data_object_id,
b_s.row_wait_file#,
b_s.row_wait_block#,
b_s.row_wait_row#) || '''',
NULL) blocked_data_querysql
FROM gv$lock a,
gv$lock b,
gv$session a_s,
gv$session b_s,
dba_objects obj
WHERE a.id1 = b.id1
AND a.id2 = b.id2
AND a.block > 0 --阻塞了其他人
AND b.request > 0 --AND ((a.INST_ID=b.INST_ID AND a.SID<>b.SID) OR (a.INST_ID<>b.INST_ID ))
AND a.sid = a_s.sid
AND a.inst_id = a_s.inst_id
AND b.sid = b_s.sid
AND b.inst_id = b_s.inst_id
AND b_s.row_wait_obj# = obj.object_id(+)
ORDER BY a.inst_id, a.sid;
