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$session_wait group by event order by 4;
2.回滚段的争用情况: select name,waits,gets,waits/gets ratio fromv$rollstat a,v$rollname b where a.usn=b.usn;
3.监控表空间的I/O比例: selectdf.tablespace_namename,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrtspyw,f.phyblkwrtpbw fromv$filestatf,dba_data_files df
where f.file#=df.file_id
4.在某个用户下找所有的索引: selectuser_indexes.table_name,user_indexes.index_name,uniqueness, column_namefrom 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;
5. 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$sysstat c
where a.statistic# = 38 and b.statistic# = 39
and c.statistic# = 40;
6. 监控 SGA 中字典缓冲区的命中率 select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"
from v$rowcache
where gets+getmisses <>0
group by parameter, gets, getmisses;
7. 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;
8. 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_sizecode_size,sum(er
ror_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;
9. 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$latch WHERE name IN ('redo allocation', 'redo copy');
10. 监控内存和硬盘的排序比率，最好使它小于10，增加sort_area_size SELECT name, value FROM v$sysstat WHERE name IN ('sorts(memory)', 'sorts (disk)');
11. 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;
12. 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
13. 找ORACLE字符集 select * from sys.props$ where name='NLS_CHARACTERSET';
14. 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
15. 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);
16. 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;
17、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$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by
value desc;
18.监控log_buffer的使用情况:(值最好小于1%，否则增加log_buffer 的大小) seletname,rbar.value,re.name,re.value,
(rbar.value*100)/re.value||'%' "radio"
from v$sysstat rbar,v$sysstat re
where rbar.name='redo buffer allocation retries'
and re.name='redo entries';
19、查看运行过的SQL语句: SELECT SQL_TEXTFROM V$SQL
