Oracle日常性能查看

判断回滚段竞争的SQL语句：（当Ratio大于2时存在回滚段竞争，需要增加更多的回滚段）

select rn.name, rs.GETS, rs.WAITS, (rs.WAITS / rs.GETS) * 100 ratio

from v$rollstat rs, v$rollname rn

where rs.USN = rn.usn

判断恢复日志竞争的SQL语句：（immediate_contention或wait_contention的值大于1时存在竞争）

select name,

(t.IMMEDIATE_MISSES /

decode((t.IMMEDIATE_GETS t.IMMEDIATE_MISSES),

-1,

(t.IMMEDIATE_GETS t.IMMEDIATE_MISSES))) * 100 immediate_contention,

(t.MISSES / decode((t.GETS t.MISSES), 0, -1, (t.GETS t.MISSES))) * 100 wait_contention

from v$latch t

where name in ('redo copy', 'redo allocation')

判断表空间碎片：（如果最大空闲空间占总空间很大比例则可能不存在碎片，如果比例较小，且有许多空闲空间，则可能碎片很多）

select t.tablespace_name,

sum(t.bytes),

max(t.bytes),

count(*),

max(t.bytes) / sum(t.bytes) radio

from dba_free_space t

group by t.tablespace_name

order by t.tablespace_name

确定命中排序域的次数：

select t.NAME, t.VALUE from v$sysstat t where t.NAME like 'sort%'

查看当前SGA值：

select * from v$sga

确定高速缓冲区命中率：（如果命中率低于70％，则应该加大init.ora参数中的DB_BLOCK_BUFFER的值）

select 1 - sum(decode(name, 'physical reads', value, 0)) /

(sum(decode(name, 'db block gets', value, 0))

sum(decode(name, 'consistent gets', value, 0))) hit_ratio

from v$sysstat t

where name in ('physical reads', 'db block gets', 'consistent gets')

确定共享池中的命中率：（如果ratio1大于1时，需要加大共享池，如果ratio2大于10％时，需要加大共享池SHARED_POOL_SIZE）

select sum(pins) pins,

sum(reloads) reloads,

(sum(reloads) / sum(pins)) * 100 ratio1

from v$librarycache

select sum(gets) gets,

sum(getmisses) getmisses,

(sum(getmisses) / sum(gets)) * 100 ratio2

from v$rowcache

查询INIT.ORA参数：

select * from v$parameter

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Oracle性能参数查看（转）

0、数据库参数属性

col PROPERTY_NAME format a25

col PROPERTY_VALUE format a30

col DESCRIPTION format a100

select * from database_properties;

select * from v$version;

1、求当前会话的SID，SERIAL#

SELECT Sid, Serial# FROM V$session

WHERE Audsid = Sys_Context('USERENV', 'SESSIONID');

2、查询session的OS进程ID

SELECT p.Spid "OS Thread", b.NAME "Name-User", s.Program, s.Sid, s.Serial#,s.Osuser, s.Machine

FROM V$process p, V$session s, V$bgprocess b

WHERE p.Addr = s.Paddr

AND p.Addr = b.Paddr And (s.sid=&1 or p.spid=&1)

UNION ALL

SELECT p.Spid "OS Thread", s.Username "Name-User", s.Program, s.Sid,s.Serial#, s.Osuser, s.Machine

FROM V$process p, V$session s

WHERE p.Addr = s.Paddr

And (s.sid=&1 or p.spid=&1)

AND s.Username IS NOT NULL;

3、根据sid查看对应连接正在运行的sql

SELECT /* PUSH_SUBQ */ Command_Type, Sql_Text, Sharable_Mem, Persistent_Mem, Runtime_Mem, Sorts,

Version_Count, Loaded_Versions, Open_Versions, Users_Opening, Executions,

Users_Executing, Loads, First_Load_Time, Invalidations, Parse_Calls,

Disk_Reads, Buffer_Gets, Rows_Processed, SYSDATE Start_Time,

SYSDATE Finish_Time, '>' || Address Sql_Address, 'N' Status

FROM V$sqlarea WHERE Address = (SELECT Sql_Address

FROM V$session WHERE Sid = &sid );

4、查找object为哪些进程所用

SELECT p.Spid, s.Sid, s.Serial# Serial_Num, s.Username User_Name,

a.TYPE Object_Type, s.Osuser Os_User_Name, a.Owner,

a.OBJECT Object_Name,

Decode(Sign(48 - Command), 1, To_Char(Command), 'Action Code #' || To_Char(Command)) Action,

p.Program Oracle_Process, s.Terminal Terminal, s.Program Program,

s.Status Session_Status

FROM V$session s, V$access a, V$process p

WHERE s.Paddr = p.Addr

AND s.TYPE = 'USER'

AND a.Sid = s.Sid

AND a.OBJECT = '&obj'

ORDER BY s.Username, s.Osuser

5、查看有哪些用户连接

SELECT s.Osuser Os_User_Name,Decode(Sign(48 - Command),1,To_Char(Command),

'Action Code #' || To_Char(Command)) Action,

p.Program Oracle_Process, Status Session_Status, s.Terminal Terminal,

s.Program Program, s.Username User_Name,

s.Fixed_Table_Sequence Activity_Meter, '' Query, 0 Memory,

0 Max_Memory, 0 Cpu_Usage, s.Sid, s.Serial# Serial_Num

FROM V$session s, V$process p

WHERE s.Paddr = p.Addr

AND s.TYPE = 'USER'

ORDER BY s.Username, s.Osuser

6、根据v.sid查看对应连接的资源占用等情况

SELECT n.NAME, v.VALUE, n.CLASS, n.Statistic# FROM V$statname n, V$sesstat v

WHERE v.Sid = &sid

AND v.Statistic# = n.Statistic#

ORDER BY n.CLASS, n.Statistic#

7、查询耗资源的进程（top session）

SELECT s.Schemaname Schema_Name,Decode(Sign(48 - Command),

1, To_Char(Command), 'Action Code #' || To_Char(Command)) Action,Status Session_Status, s.Osuser Os_User_Name, s.Sid, p.Spid,s.Serial# Serial_Num, Nvl(s.Username, '[Oracle process]') User_Name,

s.Terminal Terminal, s.Program Program, St.VALUE Criteria_Value

FROM V$sesstat St, V$session s, V$process p

WHERE St.Sid = s.Sid

AND St.Statistic# = To_Number('38')

AND ('ALL' = 'ALL' OR s.Status = 'ALL')

AND p.Addr = s.Paddr

ORDER BY St.VALUE DESC, p.Spid ASC, s.Username ASC, s.Osuser ASC

8、查看锁（lock）情况

SELECT /* RULE */ Ls.Osuser Os_User_Name, Ls.Username User_Name,Decode(Ls.TYPE,

'RW', 'Row wait enqueue lock', 'TM', 'DML enqueue lock','TX', 'Transaction enqueue lock', 'UL', 'User supplied lock') Lock_Type,o.Object_Name OBJECT,Decode(Ls.Lmode,1, NULL, 2, 'Row Share', 3, 'Row Exclusive',

4, 'Share', 5, 'Share Row Exclusive', 6, 'Exclusive',NULL) Lock_Mode,o.Owner, Ls.Sid, Ls.Serial# Serial_Num, Ls.Id1, Ls.Id2 FROM Sys.Dba_Objects o,

(SELECT s.Osuser, s.Username, l.TYPE, l.Lmode, s.Sid, s.Serial#, l.Id1,l.Id2 FROM V$session s, V$lock l

WHERE s.Sid = l.Sid) Ls

WHERE o.Object_Id = Ls.Id1

AND o.Owner <> 'SYS'

ORDER BY o.Owner, o.Object_Name;

9、查看等待（wait）情况

SELECT Ws.CLASS, Ws.COUNT COUNT, SUM(Ss.VALUE) Sum_Value

FROM V$waitstat Ws, V$sysstat Ss

WHERE Ss.NAME IN ('db block gets', 'consistent gets')

GROUP BY Ws.CLASS, Ws.COUNT;

10、求process/session的状态