38.数据的并发处理

1.管理数据的并发

select sid,serial#,username from v$session where sid in (select blocking_session from v$session);
alter system kill session '144,8982' immediate;

--1.在一个会话中
scott@ORCL10G 2023-03-04 14:39:54> update emp set sal=sal+1 where empno = 7566;

1 row updated.

Elapsed: 00:00:00.02
scott@ORCL10G 2023-03-04 14:40:26> 

--2.打开另外一个会话
scott@ORCL10G 2023-03-04 14:40:42> update emp set comm = 500 where empno = 7566;


--3.再打开一个窗口，杀掉第一次的会话
sys@ORCL10G 2023-03-04 14:42:10> select sid,serial#,username from v$session where sid in (select blocking_session from v$session);

       SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       150	  134 SCOTT

Elapsed: 00:00:00.01
sys@ORCL10G 2023-03-04 14:42:45> alter system kill session '150,134' immediate;

System altered.

Elapsed: 00:00:00.05

--4.结果
----第一个会话
scott@ORCL10G 2023-03-04 14:46:17> select  *from emp;
select	*from emp
*
ERROR at line 1:
ORA-03135: connection lost contact


ERROR:
ORA-03114: not connected to ORACLE


Elapsed: 00:00:00.01
--第二个会话
scott@ORCL10G 2023-03-04 14:40:42> update emp set comm = 500 where empno = 7566;

1 row updated.

Elapsed: 00:01:55.07

sys@ORCL10G 2023-03-04 14:56:01> select 'alter system kill session '''||sid||','||serial#||''' immediate ;' from v$session where sid in (select blocking_session from v$session) and SECONDS_IN_WAIT > 10;

'ALTERSYSTEMKILLSESSION'''||SID||','||SERIAL#||'''IMMEDIATE;'
-------------------------------------------------------------------------------------------------------------------------
alter system kill session '146,29' immediate ;

Elapsed: 00:00:00.01
sys@ORCL10G 2023-03-04 14:56:09> alter system kill session '146,29' immediate ;

System altered.

Elapsed: 00:00:00.05