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数据库 :: 数据库

监控数据库性能的SQL


http://www.gipsky.com/
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 * [1] "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
附注
  1. a.value b.value)-c.value) / (a.value b.value
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