科技行者

行者学院 转型私董会 科技行者专题报道 网红大战科技行者

知识库

知识库 安全导航

至顶网软件频道ORACLE入门之监控数据库性能的SQL

ORACLE入门之监控数据库性能的SQL

  • 扫一扫
    分享文章到微信

  • 扫一扫
    关注官方公众号
    至顶头条

  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$

作者:中国IT实验室 来源:中国IT实验室 2007年10月6日

关键字: 数据库 ORACLE

  • 评论
  • 分享微博
  • 分享邮件

  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$session_Wait group by event order by 4;
  2. 回滚段的争用情况
  select name, waits, gets, waits/gets "Ratio" from v$rollstat a, v$rollname b
  where a.usn = b.usn;
  3. 监控表空间的 I/O 比例
  select df.tablespace_name name,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw from v$filestat f, dba_data_files df where f.file# = df.file_id
  order by df.tablespace_name;
  4. 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#;
  5.在某个用户下找所有的索引
  select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name from 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;
  
  6. 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;
  
  7. 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;
  
  8. 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;
  
  9. 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_size) code_size ,sum(error_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;
  
  10. 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');
  
  11. 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)');
  
  
  12. 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;
  
  13. 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
  
  14. 找ORACLE字符集
  
   select * from sys.props$ where name='NLS_CHARACTERSET';
  
  15. 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
  
  16. 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);
  
  17. 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;
  
  18、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;
  

查看本文来源

    • 评论
    • 分享微博
    • 分享邮件