--一、oracle對select加鎖方法

create table t_test(a number,b number);

INSERT INTO t_test VALUES (1, 2);

INSERT INTO t_test VALUES (3, 4);

INSERT INTO t_test VALUES (5, 6);

COMMIT;

---session 1 模擬選中一個號碼

SELECT * FROM t_test WHERE A = 1 FOR UPDATE SKIP LOCKED;

A B

---------- ----------

1 2

---session 2 對a=1再進行select

SELECT * FROM t_test WHERE A = 1 FOR UPDATE SKIP LOCKED;

--未選定行

-- session 3 全表select

SELECT * FROM t_test FOR UPDATE SKIP LOCKED;

A B

---------- ----------

3 4

8 9

--二、查詢那些用戶，操縱了那些表造成了鎖機

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、查出被鎖的表，和鎖住這個表的會話ID

SELECT A.SESSION_ID, B.*

FROM V$LOCKED_OBJECT A, ALL_OBJECTS B

WHERE A.OBJECT_ID = B.OBJECT_ID;

--四、 查出對應的SQL語句

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 = (上面查出來的會話ID);

--五、

--１.查哪個過程被鎖

--查V$DB_OBJECT_CACHE視圖:

SELECT *

FROM V$DB_OBJECT_CACHE

WHERE OWNER = '過程的所屬用戶'

AND LOCKS != '0';

--2. 查是哪一個SID,通過SID可知道是哪個SESSION.

--查V$ACCESS視圖:

SELECT *

FROM V$ACCESS

WHERE OWNER = '過程的所屬用戶'

AND NAME = '剛才查到的過程名';

--3. 查出SID和SERIAL#

--查V$SESSION視圖:

SELECT SID, SERIAL#, PADDR FROM V$SESSION WHERE SID = '剛才查到的SID';

--查V$PROCESS視圖:

SELECT SPID FROM V$PROCESS WHERE ADDR = '剛才查到的PADDR';

--4. 殺進程

--(1).先殺ORACLE進程:

ALTER SYSTEM KILL SESSION '查出的SID,查出的SERIAL#';

--(2).再殺操作系統(tǒng)進程:

KILL - 9 '剛才查出的SPID';

--或

--ORAKILL 剛才查出的SID 剛才查出的SPID

--六、查找最耗費系統(tǒng)資源的SQL

--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;

--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;

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;

總結

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