Oracle 常用性能监控 SQL 语句
    —查看表锁 

    1. select * from sys.v_$sqlarea where disk_reads>100

    —监控事例的等待 

    1. select event,sum(decode(wait_Time,0,0,1)) "Prev", 
    2. sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot" 
    3. from v$session_Wait 
    4. group by event order by 4

    —回滚段的争用情况

    1. select name, waits, gets, waits/gets "Ratio" 
    2. from v$rollstat a, v$rollname b 
    3. where a.usn = b.usn

    —查看前台正在发出的 SQL 语句

    1. select user_name,sql_text
    2. 　　 from v$open_cursor
    3. 　　 where sid in (select sid from (select sid,serial#,username,program
    4. 　　 from v$session
    5. 　　 where status='ACTIVE'))

    —数据表占用空间大小情况

    1. select segment_name,tablespace_name,bytes,blocks 
    2. from user_segments 
    3. where segment_type='TABLE' 
    4. ORDER BY bytes DESC ,blocks DESC

    —查看表空间碎片大小

    1. select tablespace_name,round(sqrt(max(blocks)/sum(blocks))*
    2. (100/sqrt(sqrt(count(blocks)))),2) FSFI
    3. from dba_free_space
    4. group by tablespace_name order by 1

    —查看表空间占用磁盘情况

    1. select 
    2. b.file_id                                 文件 ID 号,
    3. b.tablespace_name                         表空间名,
    4. b.bytes                                 字节数,
    5. (b.bytes-sum(nvl(a.bytes,0)))                 已使用,
    6. sum(nvl(a.bytes,0))                         剩余空间,
    7. sum(nvl(a.bytes,0))/(b.bytes)*100         剩余百分比 
    8. from dba_free_space a,dba_data_files b 
    9. where a.file_id=b.file_id 
    10. group by b.tablespace_name,b.file_id,b.bytes 
    11. order by b.file_id
    12. --查看 session 使用回滚段
    13. SELECT  r.name 回滚段名,
    14. s.sid,
    15. s.serial#,
    16. s.username 用户名,
    17. t.status,
    18. t.cr_get,
    19. t.phy_io,
    20. t.used_ublk,
    21. t.noundo,
    22. substr(s.program, 1, 78) 操作程序
    23. FROM   sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r
    24. WHERE  t.addr = s.taddr and t.xidusn = r.usn
    25. ORDER  BY t.cr_get,t.phy_io

    —查看 SGA 区剩余可用内存

    1. select name,
    2. 　　　　　　sgasize/1024/1024　　　　　　　　"Allocated(M)",
    3. 　　　　　　bytes/1024　　　　　　　　　　　 "**空间(K)",
    4. 　　　　　　round(bytes/sgasize*100, 2)　　　"**空间百分比(%)"
    5. 　　 from   (select sum(bytes) sgasize from sys.v_$sgastat) s, sys.v_$sgastat f
    6. 　　 where  f.name = 'free memory'

    —监控表空间 I/O 比例

    1. select df.tablespace_name name,df.file_name "file",f.phyrds pyr, 
    2. f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw 
    3. from v$filestat f, dba_data_files df 
    4. where f.file# = df.file_id 
    5. order by df.tablespace_name

    —监控 SGA 命中率

    1. select a.value + b.value "logical_reads", 
    2. c.value "phys_reads", 
    3. round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT 
    4. RATIO" 
    5. from v$sysstat a, v$sysstat b, v$sysstat c 
    6. where a.statistic# = 38 and 
    7. b.statistic# = 39 and 
    8. c.statistic# = 40

    —监控 SGA 中字典缓冲区的命中率

    1. select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio", 
    2. (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio" 
    3. from v$rowcache 
    4. where gets+getmisses <>0 
    5. group by parameter, gets, getmisses

    —监控 SGA **享缓存区的命中率，应该小于 1%

    1. select sum(pins) "Total Pins", sum(reloads) "Total Reloads", 
    2. sum(reloads)/sum(pins) *100 libcache 
    3. from v$librarycache

    —监控 SGA 中重做日志缓存区的命中率，应该小于 1%

    1. SELECT name, gets, misses, immediate_gets, immediate_misses, 
    2. Decode(gets,0,0,misses/gets*100) ratio1, 
    3. Decode(immediate_gets+immediate_misses,0,0, 
    4. immediate_misses/(immediate_gets+immediate_misses)*100) ratio2 
    5. FROM v$latch WHERE name IN ('redo allocation', 'redo copy')

    —监控内存和硬盘的排序比率，最好使它小于 .10

    1. SELECT name, value 
    2. FROM v$sysstat 
    3. WHERE name IN ('sorts (memory)', 'sorts (disk)') 
    4. --监控字典缓冲区
    5. SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES" 
    6. FROM V$ROWCACHE

    —非系统用户建在 SYSTEM 表空间中的表

    1. SELECT owner,table_name 
    2. FROM DBA_TABLES
    3. WHERE tablespace_name in('SYSTEM','USER_DATA') AND 
    4. owner NOT IN('SYSTEM','SYS','OUTLN', 'ORDSYS','MDSYS','SCOTT', 'HOSTEAC')

    —性能最差的 SQL

    1. SELECT * FROM ( SELECT PARSING_USER_ID 
    2. EXECUTIONS,SORTS,COMMAND_TYPE,DISK_READS,sql_text 
    3. FROM v$sqlarea 
    4. ORDER BY disk_reads DESC) 
    5. WHERE ROWNUM<100

    —读磁盘数超 100 次的 sql

    1. select * from sys.v_$sqlarea where disk_reads>100

    —最频繁执行的 sql

    1. select * from sys.v_$sqlarea where executions>100

    —查询使用 CPU 多的用户 session

    1. select a.sid,spid,status,substr(a.program,1,40) 
    2. prog,a.terminal,osuser,value/60/100 value 
    3. from v$session a,v$process b,v$sesstat c 
    4. where c.statistic#=12 and 
    5. c.sid=a.sid and 
    6. a.paddr=b.addr 
    7. order by value desc

    —当前每个会话使用的对象数

    1. SELECT a.sid,s.terminal,s.program,count(a.sid) 
    2. FROM V$ACCESS a,V$SESSION s
    3. WHERE a.owner <> 'SYS'AND s.sid = a.sid 
    4. GROUP BY a.sid,s.terminal,s.program
    5. ORDER BY count(a.sid)