oracle性能监控

监控数据库性能的SQL

查看tablespace的空間使用情況
select tablespace_name,sum(bytes)/1024/1024 from dba_free_space group by tablespace_name
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;

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 ōwner='caisit'
group by segment_name;
18、找使用CPU多的用户session
              是cpu used by this session

19﹑找使用cpu和內存多的sql語句.
select sql_text from v$sqltext a where a.hashvalue=(select sql_hash_value from v$session b where b.paddr=(select

addr from v$process where spid=&pid))
20﹑ 捕獲等待的sql語句.
select w.sid,w.event,t.sql_text from v$session_wait w,v$sqltext t,v$session s
where t.hashvalue=s.sql_hash_value and s.sid=w.sid;

21﹑捕獲等待的sql語句和用戶
select user#,audsid,s.osuser,w.sid,w.event,t.sql_text from v$session_wait w,v$sqltext t,v$session s
where t.hashvalue=s.sql_hash_value and s.sid=w.sid;

22. cache hit ratio
SELECT (sum(getmisses)/sum(gets)) * 100 as "cache hit ratio" FROM v$rowcache
23. buffer cache hit ratio
SELECT (1 - (sum(decode(name, 'physical reads', value, 0)) /(sum(decode(name, 'db block gets', value, 0)) +    

sum(decode(name, 'consistent gets', value, 0))))) * 100  as "Buffer cache hit ratio" FROM    v$sysstat
24.查數據字典v$datafile,及v$filestat了解數據中是否存在I/O競爭等﹕
select substr(a.file#,1,2) "File#",a.status,a.bytes,b.phyrds,b.phywrts,substr(a.name,1,50) "File Name"
from v$datafile a,v$filestat b where a.file#=b.file#;
<PHYRDS,PHYWRTS分別表示物理磁盤讀寫的數據量>
25.日志緩沖區過小﹐會增加日志寫盤的次數﹐增加了系統的I/O負擔﹐對于日志緩沖區而言﹐可以計算失敗率﹐使用數據字典v$LATCH計算日志緩沖區的失敗率﹐應該小于1%
select name,gets,misses,immediate_gets,immediate_misses,decode(gets,0,0,misses/gets*100) ratioone,
decode(immediate_gets+immediate_misses,0,0,immediate_misses/(immediate_gets+immediate_misses)*100) ratiotwo
from v$latch where name in ('redo allocation','redo copy');
<gets表示成功等待日志緩沖區的次數。immediate_gets表示成功立即得到日志緩沖區的次數。immediate_misses表示失敗立即得到日志緩沖區的次數。日志緩沖區的失敗率表示了日志緩沖區是否足夠大﹐應該小于1%>

1、查看表空间的名称及大小
select t.tablespace_name, round(sum(bytes/(1024*1024)),0) ts_size
from dba_tablespaces t, dba_data_files d
where t.tablespace_name = d.tablespace_name
group by t.tablespace_name;

2、查看表空间物理文件的名称及大小
select tablespace_name, file_id, file_name,
round(bytes/(1024*1024),0) total_space
from dba_data_files
order by tablespace_name;

3、查看回滚段名称及大小
select segment_name, tablespace_name, r.status,
(initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent,
max_extents, v.curext CurExtent
From dba_rollback_segs r, v$rollstat v
Where r.segment_id = v.usn(+)
order by segment_name ;

4、查看控制文件
select name from v$controlfile;

5、查看日志文件
select member from v$logfile;

6、查看表空间的使用情况
select sum(bytes)/(1024*1024) as free_space,tablespace_name
from dba_free_space
group by tablespace_name;
SELECT A.TABLESPACE_NAME,A.BYTES TOTAL,B.BYTES USED, C.BYTES FREE,
(B.BYTES*100)/A.BYTES "% USED",(C.BYTES*100)/A.BYTES "% FREE"
FROM SYS.SM$TS_AVAIL A,SYS.SM$TS_USED B,SYS.SM$TS_FREE C
WHERE A.TABLESPACE_NAME=B.TABLESPACE_NAME AND A.TABLESPACE_NAME=C.TABLESPACE_NAME;

7、查看数据库库对象
select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;

8、查看数据库的版本　
Select version FROM Product_component_version
Where SUBSTR(PRODUCT,1,6)='Oracle';

9、查看数据库的创建日期和归档方式
Select Created, Log_Mode, Log_Mode From V$Database;