欢迎进入oracle社区论坛，与200万技术人员互动交流 >>进入 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$session_wait group by event order by 4; 2. 回滚段的争用情
欢迎进入oracle社区论坛，与200万技术人员互动交流 >>进入
1. 监控事例的等待
select event,sum(decode(wait_time,0,0,1)) prev,
sum(decode(wait_time,0,1,0)) curr,count(*) tot
from v$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。
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
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;