数据库监控

实现目标：尽量做到部署简单化、监控自动化。1、数据库信息查看脚本比较好说，将各个数据库结构参数查询脚本写成分级、附带说明的形式，每次执行脚本后即可得到完整的数据库结构参数信息。2、监控脚本，将各个数据库监控脚本写成附带说明的通俗易懂、易于部署的形式，能修改少量参数即可部署到新的环境中做监控。

--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　　　　　　　　　　　 "自由空间(K)",

 　　　　　　round(bytes/sgasize*100, 2)　　　"自由空间百分比(%)"

 　　 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 中共享缓存区的命中率，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 

  

--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)