1.監控事例的等待：
select event,sum(decode(wait_time,0,0,1)) prev, sum(decode(wait_time,0,1,0)) curr,count(*) from v$session_wait group by event order by 4;
2.回滾段的爭用情況：select name,waits,gets,waits/gets ratio from v$rollstat a,v$rollname b where a.usn=b.usn;
3.監控表空間的I/O比例：select df.tablespace_name name,df.file_name "ile",f.phyrds pyr,f.phyblkrd pbr,f.phywrts pyw,
f.phyblkwrt pbw from v$filestat f,dba_data_files dfwhere f.file#=df.file_id
4.監空檔案系統的I/O比例：select substr(a.file#,1,2) "#",substr(a.name,1,30) "name",a.status,a.bytes,
b.phyrds,b.phywrtsfrom v$datafile a,v$filestat bwhere a.file#=b.file#
5.在某個使用者下找所有的索引：select user_indexes.table_name, user_indexes.index_name,uniqueness,
column_namefrom user_ind_columns, user_indexeswhere user_ind_columns.index_name = user_indexes.index_nameand 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. 監控 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$sysstat cwhere a.statistic# = 38 and b.statistic# = 39 and c.statistic# = 40;
7. 監控 SGA 中字典緩衝區的命中率select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"from v$rowcache where gets+getmisses <>0group by parameter, gets, getmisses;
8. 監控 SGA 中共享快取區的命中率，應該小於1%
select sum(pins) "Total Pins", sum(reloads) "Total Reloads",sum(reloads)/sum(pins) *100 libcachefrom v$librarycache;select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins)
"reload percent" from v$librarycache;
9. 顯示所有資料庫物件的類別和大小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. 監控 SGA 中重做日誌快取區的命中率，應該小於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) ratio2FROM v$latch WHERE name IN ('redo allocation', 'redo copy');
11. 監控記憶體和硬碟的排序比率，最好使它小於 .10，增加 sort_area_size SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts (disk)');
12. 監控當前資料庫誰在執行什麼SQL語句SELECT osuser, username, sql_text from v$session a, v$sqltext bwhere a.sql_address =b.address order by address, piece;
13. 監控字典緩衝區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;

後者除以前者,此比率小於1%,接近0%為好。
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. 監控 MTSselect busy/(busy+idle) "shared servers busy" from v$dispatcher;
此值大於0.5時，引數需加大select sum(wait)/sum(totalq) "ispatcher waits" from v$queue where
type='dispatcher';select count(*) from v$dispatcher;select servers_highwater from v$mts;

servers_highwater接近mts_max_servers時，引數需加大

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 asselect tablespace_name,block_id,bytes,blocks,'free space' segment_name from dba_free_spaceunion allselect 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;

檢視碎片程度高的表
SELECT segment_name table_name , COUNT(*) extentsFROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY
segment_nameHAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);
17. 表、索引的儲存情況檢查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='&wner'group by segment_name;
18、找使用CPU多的使用者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 valuefrom v$session a,v$process b,v$sesstat cwhere c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc;
20.監控log_buffer的使用情況：(值最好小於1%，否則增加log_buffer 的大小)select rbar.name,rbar.value,re.name,re.value,
(rbar.value*100)/re.value||'%' "radio"from v$sysstat rbar,v$sysstat rewhere rbar.name='redo buffer allocation retries'and re.name='redo entries';

19、檢視執行過的SQL語句：
SELECT SQL_TEXTFROM V$SQL[@more@]

常用監控SQL

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