--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;

--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

--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;

--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;

--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)');

--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);

--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;

--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';