数据库监控

--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)