ORACLE常用性能监控SQL

Temp表空间上进程的查询

select a.tablespace, b.sid, b.serial#, a.blocks,c.sql_text
  from v$sort_usage a,v$session b,v$sqltext c
 where a.session_addr = b.saddr
   and b.sql_address = c.address
 order by a.tablespace,b.sid,b.serial#,c.address, c.piece;

查看表锁

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

监控事例的等待

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

回滚段的争用情况

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

查看前台正在发出的SQL语句

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'));

数据表占用空间大小情况

select segment_name,tablespace_name,bytes,blocks
from user_segments
where segment_type='TABLE'
ORDER BY bytes DESC ,blocks DESC;

查看表空间碎片大小

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

查看表空间占用磁盘情况

select
         b.file_id                                 文件ID号,
         b.tablespace_name                         表空间名,
         b.bytes                                 字节数,
         (b.bytes-sum(nvl(a.bytes,0)))                 已使用,
         sum(nvl(a.bytes,0))                         剩余空间,
         sum(nvl(a.bytes,0))/(b.bytes)*100         剩余百分比
         from dba_free_space a,dba_data_files b
         where a.file_id=b.file_id
         group by b.tablespace_name,b.file_id,b.bytes
         order by b.file_id;

查看Oracle 表空间使用率

SELECT D.TABLESPACE_NAME,  
       SPACE || 'M' "SUM_SPACE(M)",  
       SPACE - NVL (FREE_SPACE, 0) || 'M' "USED_SPACE(M)",  
       ROUND ( (1 - NVL (FREE_SPACE, 0) / SPACE) * 100, 2) || '%'
          "USED_RATE(%)",  
       FREE_SPACE || 'M' "FREE_SPACE(M)"
  FROM (  SELECT TABLESPACE_NAME,  
                 ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE,  
                 SUM (BLOCKS) BLOCKS  
            FROM DBA_DATA_FILES  
        GROUP BY TABLESPACE_NAME) D,  
       (  SELECT TABLESPACE_NAME,  
                 ROUND (SUM (BYTES) / (1024 * 1024), 2) FREE_SPACE  
            FROM DBA_FREE_SPACE  
        GROUP BY TABLESPACE_NAME) F  
 WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+)  
UNION ALL                                                           --如果有临时表空间  
SELECT D.TABLESPACE_NAME,  
       SPACE || 'M' "SUM_SPACE(M)",  
       USED_SPACE || 'M' "USED_SPACE(M)",  
       ROUND (NVL (USED_SPACE, 0) / SPACE * 100, 2) || '%' "USED_RATE(%)",  
       NVL (FREE_SPACE, 0) || 'M' "FREE_SPACE(M)"
  FROM (  SELECT TABLESPACE_NAME,  
                 ROUND (SUM (BYTES) / (1024 * 1024), 2) SPACE,  
                 SUM (BLOCKS) BLOCKS  
            FROM DBA_TEMP_FILES  
        GROUP BY TABLESPACE_NAME) D,  
       (  SELECT TABLESPACE_NAME,  
                 ROUND (SUM (BYTES_USED) / (1024 * 1024), 2) USED_SPACE,  
                 ROUND (SUM (BYTES_FREE) / (1024 * 1024), 2) FREE_SPACE  
            FROM V$TEMP_SPACE_HEADER  
        GROUP BY TABLESPACE_NAME) F  
 WHERE D.TABLESPACE_NAME = F.TABLESPACE_NAME(+)  
ORDER BY 1;

 查看Temp 表空间实际使用磁盘大小

Select f.tablespace_name,
       d.file_name "Tempfile name",
       round((f.bytes_free + f.bytes_used) / 1024 / 1024, 2) "total MB",
       round(((f.bytes_free + f.bytes_used) - nvl(p.bytes_used, 0)) / 1024 / 1024,
             2) "Free MB",
       round(nvl(p.bytes_used, 0) / 1024 / 1024, 2) "Used MB",
       round((round(nvl(p.bytes_used, 0) / 1024 / 1024, 2) /
             round((f.bytes_free + f.bytes_used) / 1024 / 1024, 2)) * 100,
             2) as "Used_Rate(%)"
  from SYS.V_$TEMP_SPACE_HEADER f,
       DBA_TEMP_FILES           d,
       SYS.V_$TEMP_EXTENT_POOL  p
 where f.tablespace_name(+) = d.tablespace_name
   and f.file_id(+) = d.file_id
   and p.file_id(+) = d.file_id;

 查看session使用回滚段

SELECT  r.name 回滚段名,
        s.sid,
        s.serial#,
        s.username 用户名,
        t.status,
        t.cr_get,
        t.phy_io,
        t.used_ublk,
        t.noundo,
        substr(s.program, 1, 78) 操作程序
FROM   sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r
WHERE  t.addr = s.taddr and t.xidusn = r.usn
ORDER  BY t.cr_get,t.phy_io;

 查看SGA区剩余可用内存

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

 监控表空间I/O比例

select df.tablespace_name name,df.file_name “file”,f.phyrds pyr,
f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw
from v$filestat f, dba_data_files df
where f.file# = df.file_id
order by df.tablespace_name;

 监控SGA命中率

select a.value + b.value "logical_reads",
       c.value "phys_reads",
       round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT RATIO"
from v$sysstat a, v$sysstat b, v$sysstat c
where a.statistic# = 38 and
      b.statistic# = 39 and
      c.statistic# = 40 ;

监控 SGA 中字典缓冲区的命中率

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

监控 SGA **享缓存区的命中率，应该小于1%

select sum(pins) "Total Pins", sum(reloads) "Total Reloads",
sum(reloads)/sum(pins) *100 libcache
from v$librarycache;

监控 SGA 中重做日志缓存区的命中率，应该小于1%

SELECT name, gets, misses, immediate_gets, immediate_misses,
Decode(gets,0,0,misses/gets*100) ratio1,
Decode(immediate_gets+immediate_misses,0,0,
immediate_misses/(immediate_gets+immediate_misses)*100) ratio2
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

SELECT name, value
FROM v$sysstat
WHERE name IN ('sorts (memory)', 'sorts (disk)') ;

监控字典缓冲区

SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
FROM V$ROWCACHE ;

 系统用户建在system表空间中的表">非系统用户建在SYSTEM表空间中的表

SELECT owner,table_name
FROM DBA_TABLES
WHERE tablespace_name in('SYSTEM','USER_DATA') AND
      owner NOT IN('SYSTEM','SYS','OUTLN', 'ORDSYS','MDSYS','SCOTT', 'HOSTEAC');

性能最差的SQL

SELECT * FROM ( SELECT PARSING_USER_ID EXECUTIONS,SORTS,COMMAND_TYPE,DISK_READS,sql_text
                FROM v$sqlarea
                ORDER BY disk_reads DESC)
WHERE ROWNUM<100;

读磁盘数超100次的sql

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

最频繁执行的sql

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

 查询使用CPU多的用户session

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

当前每个会话使用的对象数

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

查询数据库当前进程的连接数

select count(*) from v$process

查看数据库当前会话的连接数

select count(*) from v$session

 查看数据库的并发连接数

select count(*) from v$session where status='ACTIVE'

 查看当前数据库建立的会话情况

select sid,serial#,username,program,machine,status from v$session

 查询数据库允许的最大连接数 或者 show parameter processes

select value from v$parameter where name ='processes'

修改数据库允许的最大连接数 alter system set processes = 300 scope = spfile

查看当前有哪些用户正在使用数据

select osuser,a.username,cpu_time/executions/1000000||'s',sql_fulltext,machine from v$session a,v$sqlarea b where a.sql_address = b.address order by cpu_time/executions desc