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;
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原文地址：http://hbxztc.blog.51cto.com/1587495/1896136
