1.查看当前正在执行的等待情况
SELECT TA.sid ,
TA.seq# ,
TB.Username ,
TB.Terminal ,
TB.Program ,
Decode(TB.Command,0 ,'[ 0] NoCommand',
1 ,'[ 1] CreateTable',
2 ,'[ 2] Insert',
3 ,'[ 3] Select',
6 ,'[ 6] Update',
7 ,'[ 7] Delete',
9 ,'[ 9] CreateIndex',
15,'[15] AlterTable',
21,'[21] CreateView',
23,'[23] ValidateIndex',
35,'[35] AlterDatabase',
39,'[39] CreateTablespace',
41,'[41] DropTablespace',
40,'[40] AlterTablespace',
53,'[53] DropUser',
62,'[62] AnalyzeTable',
63,'[63] AnalyzeIndex',
TB.Command || 'ther') Command,
DECODE(TA.event,'db file scattered read','通表扫描',
'db file sequential read','索引扫描',
'latch free','latch contention',
'free buffer waits','等待DBWR 清除弄脏块',
'log file sync','LGWR写COMMIT或ROLLBACK数据',
'write complete waits','等待DBWR写',
'buffer busy wait','可能是FreeList竞争',
TA.event) Event,
TA.p1text,TA.p1 ,TA.p1raw ,
TA.p2text,TA.p2 ,TA.p2raw ,
TA.p3text,TA.p3 ,TA.p3raw ,
TA.wait_time ,
TA.seconds_in_wait,
TA.state,
TB.sql_address,
TB.sql_hash_value
FROM v$session_wait TA,
v$session TB
WHERE --TB.terminal='FUTURE-MGET' AND
TA.SID = TB.SID AND
TA.event NOT LIKE '% timer' AND
TA.event NOT LIKE 'rdbms ipc message' AND
TA.event NOT LIKE 'SQL*Net %'
2.查看连接等待事件
SELECT Sid || ' ' || Event || ' ' || Total_Waits || ' ' || Average_Wait
FROM V$session_Event
WHERE Sid = &上面的SID
3.每个用户命中率(命中率应该超过90%)
SELECT TA.Sid "连接ID",
username "用户名",
consistent_gets "读一致性",
block_gets "缓冲区读",
physical_reads "物理读",
100*(consistent_gets+block_gets-physical_reads)/(consistent_gets+block_gets) hiratio,
TA.sql_address,
TA.sql_hash_value
FROM v$session TA,
v$sess_io TB
WHERE TA.sid=TB.sid
AND (consistent_gets+block_gets)>0
AND username IS NOT NULL
ORDER BY 6 ASC;
4.查询耗资源的SQL
SELECT ADDRESS,HASH_VALUE,
SUBSTR(SQL_TEXT, 1, 20) TEXT,
BUFFER_GETS,
EXECUTIONS,
BUFFER_GETS / EXECUTIONS AVG
FROM V$SQLAREA
WHERE EXECUTIONS > 0
AND BUFFER_GETS > 100000
ORDER BY 6;
5.查询耗CPU资源的SQL
SELECT SS.SID,
Decode(SE.Command,0 ,'[ 0] NoCommand',
1 ,'[ 1] CreateTable',
2 ,'[ 2] Insert',
3 ,'[ 3] Select',
6 ,'[ 6] Update',
7 ,'[ 7] Delete',
9 ,'[ 9] CreateIndex',
15,'[15] AlterTable',
21,'[21] CreateView',
23,'[23] ValidateIndex',
35,'[35] AlterDatabase',
39,'[39] CreateTablespace',
41,'[41] DropTablespace',
40,'[40] AlterTablespace',
53,'[53] DropUser',
62,'[62] AnalyzeTable',
63,'[63] AnalyzeIndex',
SE.Command || 'ther'),
SS.VALUE CPU,
SE.USERNAME,
SE.PROGRAM,
SE.sql_address,
SE.sql_hash_value
FROM V$SESSTAT SS, V$SESSION SE
WHERE SS.STATISTIC# IN
(SELECT STATISTIC#
FROM V$STATNAME
WHERE NAME = 'CPU used by this session')
AND SE.SID = SS.SID
AND SS.SID > 6
ORDER BY SS.SID;
6.v$session中的列部分说明
0 - WAITING (当前等待的 Session)
-2 - WAITED UNKNOWN TIME (最后等待持续时间未知)
-1 - WAITED SHORT TIME (最后的等待 <1/100 秒)
>0 - WAITED KNOWN TIME (WAIT_TIME = 最后等待持续时间)
STATUS VARCHAR2(8) Status of the session:
ACTIVE - Session currently executing SQL
INACTIVE - sql及其session没有释放或正常退出......
KILLED - Session marked to be killed
CACHED - Session temporarily cached for use by Oracle*XA
SNIPED - Session inactive, waiting on the client
7.根据上面的地址找对应的SQL
SELECT *
FROM v$sqltext
WHERE address=HexToRaw('0700000036D20268')
AND hash_value=2348072240
ORDER BY address,hash_value,piece;
--或者
SELECT *
FROM v$sqlarea
WHERE address=HexToRaw('0700000036D20268')
AND hash_value=2348072240
ORDER BY address,hash_value;
HexToRaw('0700000036D20268')和hash_value=2348072240
对应的是v$session中的sql_address,sql_hash_value,
这两个值分别在楼上的SQL中有取出
8.根据ID找SQL
SELECT tb.command_type,
Tb.Piece,
Tb.Sql_Text
FROM V$open_Cursor Ta,
V$sqltext Tb
WHERE Ta.Sid = &SID
AND Ta.Address = Tb.Address
AND Ta.Hash_Value = Tb.Hash_Value
ORDER BY Tb.Address,
Tb.Hash_Value,
Tb.Piece ASC;
9.寻找没有使用绑定变量的sql语句
SELECT Plan_Hash_Value,
COUNT(*)
FROM V$sql
WHERE Plan_Hash_Value <> 0
GROUP BY Plan_Hash_Value
ORDER BY 2 DESC;
10.查询正打开的游标
SELECT User_Name,
Sql_Text
FROM V$open_Cursor
WHERE Sid IN (SELECT Sid
FROM (SELECT Sid,
Serial#,
Username,
Program
FROM V$session
WHERE Status = 'ACTIVE'))
子查询
SELECT Sid,
Serial#,
Username,
Program
FROM V$session
WHERE Status = 'ACTIVE'
查出的是不活动的session的sid
10.锁表检查
锁与等待，如果发生了锁等待，我们可能更想知道是谁锁了表而引起谁的等待以下的语句可以
查询到谁锁了表，而谁在等待。
SELECT /*+ rule */
LPAD(' ', DECODE(L.XIDUSN, 0, 3, 0)) || L.ORACLE_USERNAME USER_NAME,
O.OWNER,
O.OBJECT_NAME,
O.OBJECT_TYPE,
--DECODE(L.TYPE, 'TM', 'TABLE LOCK', 'TX', 'ROW LOCK', NULL) LOCK_LEVEL,
Decode(L.Locked_Mode,0,'[0] none',
1,'[1] null 空',
2,'[2] Row-S 行共享(RS)：共享表锁，sub share ',
3,'[3] Row-X 行独占(RX)：用于行的修改，sub exclusive ',
4,'[4] Share 共享锁(S)：阻止其他DML操作，share',
5,'[5] S/Row-X 共享行独占(SRX)：阻止其他事务操作，share/sub exclusive ',
6,'[6] exclusive 独占(X)：独立访问使用，exclusive ',
'['||L.Locked_Mode||'] Other Lock') LockMode,
S.SID,
S.SERIAL#,
S.sql_address,
S.sql_hash_value
FROM V$LOCKED_OBJECT L, DBA_OBJECTS O, V$SESSION S
WHERE L.OBJECT_ID = O.OBJECT_ID
AND L.SESSION_ID = S.SID
ORDER BY O.OBJECT_ID, XIDUSN DESC;
11.锁类型检查
用户锁，数据库的锁有的时候是比较耗费资源的，特别是发生锁等待的时候，我们必须找到发生
等待的锁，有可能的话，杀掉该进程。
这个语句将查找到数据库中所有的DML语句产生的锁，还可以发现，任何DML语句其实产生了两个锁，
一个是表锁，一个是行锁。
可以通过《删除回话及进程》来杀掉会话
SELECT /*+ rule */
S.USERNAME,
DECODE(L.TYPE, 'TM', 'TABLE LOCK', 'TX', 'ROW LOCK', NULL) LOCK_LEVEL,
Decode(L.LMode,0,'[0] none',
1,'[1] null 空',
2,'[2] Row-S 行共享(RS)：共享表锁，sub share ',
3,'[3] Row-X 行独占(RX)：用于行的修改，sub exclusive ',
4,'[4] Share 共享锁(S)：阻止其他DML操作，share',
5,'[5] S/Row-X 共享行独占(SRX)：阻止其他事务操作，share/sub exclusive ',
6,'[6] exclusive 独占(X)：独立访问使用，exclusive ',
'['||L.LMode||'] Other Lock') LockMode,
O.OWNER,
O.OBJECT_NAME,
O.OBJECT_TYPE,
S.SID,
S.SERIAL#,
S.TERMINAL,
S.MACHINE,
S.PROGRAM,
S.OSUSER,
S.sql_address,
S.sql_hash_value
FROM V$SESSION S, V$LOCK L, DBA_OBJECTS O
WHERE L.SID = S.SID
AND L.ID1 = O.OBJECT_ID(+)
AND S.USERNAME IS NOT NULL
12.当前用户排序情况
SELECT s.sid "连接ID",
machine "对方机器",username "系统用户",
program "应用程序",osuser "登陆系统用户",
sd.VALUE "磁盘排序",sm.VALUE "内存排序",
sr.VALUE "排序行数",
Round(sm.VALUE/Decode(Sign(sm.VALUE+sr.VALUE),0,NULL,(sm.VALUE+sr.VALUE)*100),4) "排序效率(%)",
s.sql_address,
s.sql_hash_value
FROM v$session s,
v$sesstat sd,
v$sesstat sm,
v$sesstat sr
WHERE s.sid = sd.sid AND
s.sid = sm.sid AND
s.sid = sr.sid AND
sd.statistic# = 101 AND
sm.statistic# = 100 AND
sr.statistic# = 102 AND
s.TYPE != 'BACKGROUND'
ORDER BY 6 Desc;
13.检查文件物理IO读写
SELECT name,phyrds,phywrts
FROM v$datafile TA,
v$filestat TB
WHERE TA.file#=TB.File#
将读写比较多的文件放到速度比较快的硬盘上
或者将集中读写的文件分布到不同的硬盘上
14.优化日志缓存
日志高速缓存：
=================================================================================
SELECT Latch "Latch",
Gets "成功",
misses "失败",
immediate_gets "立即成功",
immediate_misses "立即失败",
IGetsHitRatio "IGets Hit Ratio (%)",
GetsHitRatio "Gets Hit Ratio (%)",
DECODE(Sign(GetsHitRatio-99),1,'正常','请增加log_buffer') "争用",
DECODE(Sign(GetsHitRatio-99),1,'正常','请增加log_buffer') "立即争用"
FROM (SELECT Substr(name,1,20) Latch,
gets Gets,
misses misses,
immediate_gets immediate_gets,
immediate_misses immediate_misses,
Round(100*(1-immediate_misses/Decode(immediate_misses+immediate_gets,0,NULL,immediate_misses+immediate_gets)),2) IGetsHitRatio,
Round(100*(1-misses/Decode(misses+gets,0,NULL,misses+gets)),2) GetsHitRatio
FROM v$Latch
WHERE name like '%redo%')
如果失败超过成功的1%，就可能出现Redo allocation和/或Redo Copy Latch争用，减少或消除
此争用是内存调整进程的一部分。
--查看日志缓冲区大小【三个值可能不一样V$parameter是初始化值】
SELECT Substr(NAME, 1, 10) NAME,
Substr(VALUE, 1, 10) VALUE
FROM V$parameter
WHERE NAME = 'log_buffer';
SELECT * FROM v$sgastat WHERE pool IS NULL
SELECT * FROM v$sga;
