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在对指定表做append操作,其他再做truncate时候,会产生锁表,如下验证步骤,
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1、创建测试表,
create table test_lock(id number, value varchar2(200));
2、执行append语句;并且不做提交,insert /*+append*/ into test_lock values(1,1);
3、再次执行清表语句,truncate table test_lock;报锁表错误,
4、查看锁表语句,发现被锁表,
select b.object_name, t.*
from v$locked_object t, user_objects b
where t.object_id = b.object_id
Session1创建测试表:
SQL create table test (id number (10) not null , name varchar(20), primary key(id));
Table created.
SQL desc test;
Name Null? Type
----------------------------------------- -------- ----------------------------
ID NOT NULL NUMBER(10)
NAME VARCHAR2(20)
SQL insert into test values(001,'tom');
1 row created.
SQL insert into test values(002,'lisa');
1 row created.
SQL insert into test values(003,'joy');
1 row created.
SQL insert into test values(004,'jia');
1 row created.
查看test表信息
SQL update test set name='xue' where name='joy';
1 row updated.
SQL commit;
Commit complete.
SQL select * from test updata;
ID NAME
---------- --------------------
1 tom
2 lisa
3 xue
4 jia
重新打开session 2:
SQL select * from test;
ID NAME
---------- --------------------
1 tom
2 lisa
3 xue
4 jia
update模拟锁表
SQL update test set name='da' where name='tom';
1 row updated.
注:不提交
Session2查询:
SQL select * from test;
ID NAME
---------- --------------------
1 tom
2 lisa
3 xue
4 jia
查看哪个表被锁
SQL select b.owner,b.object_name,a.session_id,a.locked_mode from v$locked_object a,dba_objects b where b.object_id = a.object_id;
OWNER
------------------------------
OBJECT_NAME
--------------------------------------------------------------------------------
SESSION_ID LOCKED_MODE
---------- -----------
SYS
TEST
23 3
查看是哪个session引起的
SQL select b.username,b.sid,b.serial#,logon_time from v$locked_object a,v$session b where a.session_id = b.sid order by b.logon_time;
USERNAME SID SERIAL# LOGON_TIM
------------------------------ ---------- ---------- ---------
SYS 23 23 02-JAN-20
杀掉对应进程
SQL alter system kill session'23,23';
System altered.
其中23为sid,23为serial#.
SQL select b.owner,b.object_name,a.session_id,a.locked_mode from v$locked_object a,dba_objects b where b.object_id = a.object_id;
no rows selected
SQL select b.username,b.sid,b.serial#,logon_time from v$locked_object a,v$session b where a.session_id = b.sid order by b.logon_time;
no rows selected
session 1查询:
SQL select * from test;
select * from test
*
ERROR at line 1:
ORA-00028: your session has been killed
SQL select * from test;
select * from test
*
ERROR at line 1:
ORA-01012: not logged on
Process ID: 5366
Session ID: 23 Serial number: 23
重新连接SQL
[oracle@localhost ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Thu Jan 2 11:39:53 2020
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL select * from test updata;
ID NAME
---------- --------------------
1 tom
2 lisa
3 xue
4 jia
一些ORACLE中的进程被杀掉后,状态被置为"killed",但是锁定的资源很长时间不释放,有时实在没办法,只好重启数据库。现在提供一种方法解决这种问题,那就是在ORACLE中杀不掉的,在OS一级再杀。
1.下面的语句用来查询哪些对象被锁:
select object_name,machine,s.sid,s.serial#
from v$locked_object l,dba_objects o ,v$session s
where l.object_id = o.object_id and l.session_id=s.sid;
2.下面的语句用来杀死一个进程:
alter system kill session '24,111'; (其中24,111分别是上面查询出的sid,serial#)
【注】以上两步,可以通过Oracle的管理控制台来执行。
3.如果利用上面的命令杀死一个进程后,进程状态被置为"killed",但是锁定的资源很长时间没有被释放,那么可以在os一级再杀死相应的进程(线程),首先执行下面的语句获得进程(线程)号:
select spid, osuser, s.program
from v$session s,v$process p
where s.paddr=p.addr and s.sid=24 (24是上面的sid)
4.在OS上杀死这个进程(线程):
1)在unix上,用root身份执行命令:
#kill -9 12345(即第3步查询出的spid)
2)在windows(unix也适用)用orakill杀死线程,orakill是oracle提供的一个可执行命令,语法为:
orakill sid thread
其中:
sid:表示要杀死的进程属于的实例名
thread:是要杀掉的线程号,即第3步查询出的spid。
例:c:orakill orcl 12345
一般先查询并找到被锁定的表,解锁代码如下:
--释放SESSION SQL:
--alter system kill session 'sid, serial#';
ALTER system kill session '23, 1647';