1. 監控事例的等待
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;

注解：order by 4 指按第4列進行排序

　　session在數據庫中當前正在等待什么，每一個連接到實例的session都對應一條記錄。

　　具體說明見： http://hi.baidu.com/sevenqxy/blog/item/7874322e4af4b4574ec2261d.html

2. 回滾段的爭用情況
select name, waits, gets, waits/gets "Ratio"
from v$rollstat a, v$rollname b
where a.usn = b.usn;

3. 監控表空間的 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. 監控文件系統的 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.在某個用戶下找所有的索引
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. 監控 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. 監控 SGA 中字典緩沖區的命中率
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. 監控 SGA 中共享緩存區的命中率，應該小于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. 顯示所有數據庫對象的類別和大小
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. 監控 SGA 中重做日志緩存區的命中率，應該小于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.?? 監控內存和硬盤的排序比率，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. 監控當前數據庫誰在運行什么SQL語句
SELECT osuser, username, sql_text from v$session a, v$sqltext b
where a.sql_address =b.address order by address, piece;

13. 監控字典緩沖區
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%為好。
select sum(gets) "dictionary gets",sum(getmisses) "dictionary cache get misses",sum(getmisses)/sum(gets) from v$rowcache

14. 找ORACLE字符集(也可以用來查看日期格式)
select * from sys.props$ where name='NLS_CHARACTERSET';

15. 監控 MTS
select busy/(busy+idle) "shared servers busy" from v$dispatcher;
此值大于0.5時，參數需加大

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時，參數需加大

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 ('IES')
GROUP BY segment_name HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);

17. 表、索引的存儲情況檢查
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多的用戶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;

?

19、查看表空間使用情況的SQL語句：??
select a.tablespace_name "表空間名",total 表空間大小,free 表空間剩余大小,??
(total-free) 表空間使用大小, round((total-free)/total,4)*100?? "使用率?? %",
(select file_name from dba_data_files where tablespace_name=a.tablespace_name and rownum<2) "文件名"??
from????
?(select tablespace_name,sum(bytes) free? from dba_free_space group by tablespace_name) a,??
?(select tablespace_name,sum(bytes) total from dba_data_files group by tablespace_name) b??
where a.tablespace_name=b.tablespace_name???
--創建表空間及數據文件?
create tablespace iests datafile 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORACLE\IES_1.DBF' size 200m reuse autoextend on next 50m;
--給表空間添加數據文件
alter tablespace iests add datafile 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORACLE\IES_2.DBF' size 200m reuse autoextend on next 50m;
--擴展已有數據文件的大小
alter database datafile 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORACLE\SYSTEM01.DBF' resize 600M;

oracle性能檢測sql語句