Oracle常用监控SQL

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 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 "ile",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
 
4.监空文件系统的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$dispatcher;
此值大于0.5时，参数需加大
select sum(wait)/sum(totalq) "ispatcher waits" from v$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 wner='&wner'
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;
 
20.监控log_buffer的使用情况：(值最好小于1%，否则增加log_buffer 的大小)
select rbar.name,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_TEXT
FROM V$SQL