使用DBMS_ROWID获取被阻塞行的rowid

218次阅读

共计 4086 个字符，预计需要花费 11 分钟才能阅读完成。

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
linuxidc@ORCL>select distinct sid from v$mystat;

SID
———-
22

linuxidc@ORCL>
zx@ORCL>update zx set name=’zx’ where id=1;

1 row updated.

#session 2
linuxidc@ORCL>select distinct sid from v$mystat;

SID
———-
145

linuxidc@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

linuxidc@ORCL>col event for a40
linuxidc@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

linuxidc@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

linuxidc@ORCL>col owner for a10
linuxidc@ORCL>col object_name for a10
linuxidc@ORCL>col rowid for a30
linuxidc@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
linuxidc@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;