Oracle Lock 學習

1.顯示Linux數據庫中鎖信息

select sid,addr kaddr,type,lmode,block from v$lock;

      SID KADDR            TY      LMODE      BLOCK-
 

---------- ---------------- -- ---------- ----------
         3 0000000077459298 XR          1          0
         3 0000000077459368 RD          1          0
         3 0000000077459438 CF          2          0
         3 00000000774595D8 RS          2          0
       127 00000000774596A8 PW          3          0
       189 0000000077459778 RT          6          0
       196 0000000077459848 AE          4          0
       190 0000000077459918 AE          4          0
        66 00000000774599E8 TS          3          0
       127 0000000077459AB8 MR          4          0
       127 0000000077459B88 MR          4          0

       SID KADDR            TY      LMODE      BLOCK
---------- ---------------- -- ---------- ----------
       127 0000000077459C58 MR          4          0
       127 0000000077459D28 MR          4          0
       127 0000000077459DF8 MR          4          0
       191 0000000077459EC8 AE          4          0
       191 0000000077459FB0 TX          0          0
       133 000000007745A080 AE          4          0
       196 00007F913A138DE0 TM          3          0
       191 00007F913A138DE0 TM          3          0
       196 0000000076034228 TX          6          1

2.持有鎖session 196 信息

執行語句
SQL> update dept set dname='sale' where deptno='30';

1 row updated.

SQL> SELECT SID FROM V$MYSTAT WHERE ROWNUM =1;

       SID
----------
       196

SQL> select sid,username from v$session where sid in
  2  (select sid from v$lock where block=1);

       SID USERNAME
---------- ------------------------------
       196 SYS

3.顯示爭用鎖session 191的 SID,username,ID1，執行SQL語句
爭用session執行語句
SQL> update dept set dname='sale' where deptno='30';
session 191無法獲得RX鎖，等待持有鎖session 196釋放RX

select B.sid,b.username,D.id1,a.sql_text
from v$session b,v$lock D,v$sqltext A
where B.lockwait=d.kaddr
and a.address=b.sql_address
and a.hash_value=b.sql_hash_value;

       SID USERNAME                              ID1 SQL_TEXT
---------- ------------------------------ ---------- ----------------------------------------------------------------
       191 SYS                                393226 update dept set dname='sale' where deptno='30'

4.顯示鎖會話進程信息

SELECT s.oSUSEr "os_user",
s.username "user",
s.sid "sid",
s.serial# "serial#",
s.process "pid",
s.status "status",
l.name "Object_locked",
l.mode_held "lock Held"
FROM v$session s,dba_dml_locks l,v$process p
where l.session_id = s.sid and p.addr=s.paddr;

os_user                        user                                  sid    serial# pid                      status   Object_locked                  lock Held
------------------------------ ------------------------------ ---------- ---------- ------------------------ -------- ------------------------------ -------------
Oracle                         SYS                                   196         25 4549                     INACTIVE DEPT                           Row-X (SX)
Oracle                         SYS                                   191         19 4867                     ACTIVE   DEPT                           Row-X (SX)

持有TX 196 session status為inactive，想要獲得TX鎖191 session status 為Active
 

5.kill Session

可以選擇殺掉連個中的任何一個session，以保證更新成功。
SQL> alter system kill session 'sid,serial#';
SQL> alter system kill session '196,25';

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