Oracle监控的关键指标（一）

先收集一些Oracle的关键指标，最近有空的话再考虑将一些比较有代表性的监控点进行指标化，指标化的数据在通过python脚本对进行性能上监控，最终部署在目前维护的oracle数据库上。

0、找使用CPU多的用户session

select a.sid,spid,status,substr(a.program,1,10) 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;

1、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; 

2、监控表空间的 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;

3、监控文件系统的 I/O 比例

select substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",      
a.status, a.bytes, b.phyrds, b.phywrts      
from v$datafile a, v$filestat b      
where a.file# = b.file#;      

4、监控 SGA 的命中率

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;      

5、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;      

6、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;

select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent" 
from v$librarycache; 

7、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'); 

8、监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size

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

9、查看碎片程度最高的表

SELECT segment_name table_name , COUNT(*) extents 
FROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY segment_name
HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name); 

10、表、索引的存储情况检查

select segment_name,sum(bytes),count(*) ext_quan from dba_extents where      
tablespace_name='&tablespace_name' and segment_type='TABLE' group by tablespace_name,segment_name;     
 
select segment_name,count(*) from dba_extents where segment_type='INDEX' and owner='&owner'     
group by segment_name;