解析oracle对select加锁的方法以及锁的查询
解析oracle对select加锁的方法以及锁的查询
一、oracle对select加锁方法
代码如下:
create table test(a number,b number); insert into test values(1,2); insert into test values(3,4); insert into test values(8,9); commit; ---session 1 模拟选中一个号码 SQL> select * from test where a =1 for update skip locked; A B ---------- ---------- 1 2 ---session 2 对a=1再进行select SQL> select * from test where a = 1 for update skip locked; 未选定行 -- session 3 全表select SQL> select * from test for update skip locked; A B ---------- ---------- 3 4 8 9 SQL>
二、查询那些用户,操纵了那些表造成了锁机
代码如下:
SELECT s.username, decode(l.type,'TM','TABLE LOCK', 'TX','ROW LOCK', NULL) LOCK_LEVEL, o.owner,o.object_name,o.object_type, s.sid,s.serial#,s.terminal,s.machine,s.program,s.osuser FROM v$session s,v$lock l,all_objects o WHERE l.sid = s.sid AND l.id1 = o.object_id(+) AND s.username is NOT Null
三、查出被锁的表,和锁住这个表的会话ID
select a.session_id ,b.* from v$locked_object a,all_objects b
where a.object_id=b.object_id
四、 查出对应的SQL语句
代码如下:
select vs.SQL_TEXT,vsess.sid,vsess.SERIAL#,vsess.MACHINE,vsess.OSUSER ,vsess.TERMINAL,vsess.PROGRAM,vs.CPU_TIME,vs.DISK_READS from v$sql vs,v$session vsess where vs.ADDRESS=vsess.SQL_ADDRESS and vsess.sid=(上面查出来的会话ID)
五、
1.查哪个过程被锁
查V$DB_OBJECT_CACHE视图:
SELECT * FROM V$DB_OBJECT_CACHE WHERE OWNER='过程的所属用户' AND LOCKS!='0';
2. 查是哪一个SID,通过SID可知道是哪个SESSION.
查V$ACCESS视图:
SELECT * FROM V$ACCESS WHERE OWNER='过程的所属用户' AND NAME='刚才查到的过程名';
3. 查出SID和SERIAL#
查V$SESSION视图:
SELECT SID,SERIAL#,PADDR FROM V$SESSION WHERE SID='刚才查到的SID'
查V$PROCESS视图:
SELECT SPID FROM V$PROCESS WHERE ADDR='刚才查到的PADDR';
4. 杀进程
(1).先杀ORACLE进程:
ALTER SYSTEM KILL SESSION '查出的SID,查出的SERIAL#';
(2).再杀操作系统进程:
KILL -9 刚才查出的SPID
或
ORAKILL 刚才查出的SID 刚才查出的SPID
六、查找最耗费系统资源的SQL
代码如下:
--CPU select b.sql_text, a.buffer_gets, a.executions, a.buffer_gets/decode(a.executions , 0 , 1 , a.executions), c.username from V$sqlarea a, v$sqltext_with_newlines b, dba_users c where a.parsing_user_id = c.user_id and a.address = b.address order by a.buffer_gets desc , b.piece
代码如下:
--IO select b.sql_text, a.disk_reads, a.executions, a.disk_reads/decode(a.executions , 0 , 1 , a.executions), c.username from v$sqlarea a, v$sqltext_with_newlines b, dba_users c where a.parsing_user_id = c.user_id and a.address = b.address order by a.disk_reads desc , b.piece
代码如下:
select s.sid,s.value "CPU Used" from v$sesstat s,v$statname n where s.statistic#=n.statistic# and n.name='CPU used by this session' and s.value>0 order by 2 desc;
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