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总结--常用的监控SQL语句集合


  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(*)from v$session_wait group by event order by 4;
  
  2.回滚段的争用情况:
  
  select name,waits,gets,waits/gets ratio fromv$rollstat a,v$rollname b where a.usn=b.usn;
  
  3.监控表空间的I/O比例:
  
  selectdf.tablespace_namename,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrtspyw,f.phyblkwrtpbw fromv$filestatf,dba_data_files df
  
  where f.file#=df.file_id
  
  4.在某个用户下找所有的索引:
  
  selectuser_indexes.table_name,user_indexes.index_name,uniqueness, column_namefrom user_ind_columns, user_indexes
  
  where user_ind_columns.index_name = user_indexes.index_name
  
  and user_ind_columns.table_name = user_indexes.table_name
  
  order by user_indexes.table_type, user_indexes.table_name,
  
  user_indexes.index_name, column_position;
  
  5. 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;
  
  6. 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;
  
  7. 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;
  
  8. 显示所有数据库对象的类别和大小
  
  select count(name) num_instances ,type ,sum(source_size)
  
  source_size,sum(parsed_size)parsed_size,
  
  sum(code_sizecode_size,sum(er
  
  ror_size) error_size,
  
  sum(source_size) +sum(parsed_size) +sum(code_size)
  
  +sum(error_size) size_required
  
  from dba_object_size
  
  group by type order by 2;
  
  9. 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');
  
  10. 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)');
  
  11. 监控当前数据库谁在运行什么SQL语句
  
  SELECT osuser, username, sql_text from v$session a, v$sqltext b
  
  where a.sql_address =b.address order by address, piece;
  
  12. 监控字典缓冲区
  
  SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM V$LIBRARYCACHE;
  
  SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE" FROM V$ROWCACHE;SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE EXECUTING" FROM V$LIBRARYCACHE; 后者除以前者,此比率小于1%,接近0%为好。SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"FROM V$ROWCACHE
  
  13. 找ORACLE字符集
  
  select * from sys.props$ where name='NLS_CHARACTERSET';
  
  14. 监控 MTS
  
  select busy/(busy+idle) "shared servers busy" from v$dispatcher;
  
  此值大于0.5时,参数需加大
  
  select sum(wait)/sum(totalq) "dispatcher waits" from v$queue
  
  where type='dispatcher';
  
  select count(*) from v$dispatcher;
  
  select servers_highwater from v$mts;
  
  servers_highwater接近mts_max_servers时,参数需加大
  
  15. 碎片程度
  
  select tablespace_name,count(tablespace_name) from dba_free_space
  
  group by tablespace_name
  
  having count(tablespace_name)>10;
  
  alter tablespace name coalesce;
  
  alter table name deallocate unused;
  
  create or replace view ts_blocks_v as
  
  select tablespace_name,block_id,bytes,blocks,'free space'
  
  segment_name from dba_free_space
  
  union all
  
  select tablespace_name,block_id,bytes,blocks,segment_name from
  
  dba_extents;
  
  select * from ts_blocks_v;
  
  select tablespace_name,sum(bytes),max(bytes),count(block_id) from
  
  dba_free_space
  
  group by tablespace_name;
  
  查看碎片程度高的表
  
  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);
  
  16. 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;
  
  17、找使用CPU多的用户session
  
  12是cpu used by this 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;
  
  18.监控log_buffer的使用情况:(值最好小于1%,否则增加log_buffer 的大小)
  
  seletname,rbar.value,re.name,re.value,
  
  (rbar.value*100)/re.value||'%' "radio"
  
  from v$sysstat rbar,v$sysstat re
  
  where rbar.name='redo buffer allocation retries'
  
  and re.name='redo entries';
  
  19、查看运行过的SQL语句:
  
  SELECT SQL_TEXTFROM V$SQL
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