經常使用SQL監控腳本

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.回滾段的爭用狀況： 
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： 
col name format a10
col file format a50

set linesize 199
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 

4.監控文件系統的I/O比例： 
select substr(a.file#,1,2) "#",substr(a.name,1,30) "name",a.status,a.bytes, 
b.phyrds,b.phywrts 
from v$datafile a,v$filestat b 
where a.file#=b.file# 

5.在某個用戶下找全部的索引： 
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. 監控 SGA 的Buffer Cache 中的命中率 
/*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$sysstat c 
where a.statistic# = 38 and b.statistic# = 39 
and c.statistic# = 40; 
*/
select 1-((a.value-b.value-c.value)/d.value)
from v$sysstat a,v$sysstat b,v$sysstat c,v$sysstat d
where a.name='physical reads' and
b.name='physical reads direct' and
c.name='physical reads direct (lob)' and
d.name='session logical reads';

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 <>0 
group by parameter, gets, getmisses; 

8. 監控 SGA 中共享緩存區的命中率，應該小於1% 
select sum(pins) "Total Pins", sum(reloads) "Total Reloads", 
sum(reloads)/sum(pins) *100 libcache 
from v$librarycache; 
#I f the reloads-to-pins ratio is greater than 1%,increase the value of the SHARED_POOL_SIZE parameter.
來自OCP9i教材

select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent" 
from v$librarycache; 


9. 顯示全部數據庫對象的類別和大小 
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 中重作日誌緩存區的命中率，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) ratio2 
FROM v$latch WHERE name IN (''redo allocation'', ''redo copy''); 

11. 監控內存和硬盤的排序比率，最好使它小於 .10，增長 sort_area_size 
SELECT name, value FROM v$sysstat WHERE name IN (''sorts (memory)'', ''sorts (disk)''); 

12. 監控當前數據庫誰在運行什麼SQL語句 
SELECT osuser, username, sql_text from v$session a, v$sqltext b 
where 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; 

後者除之前者,此比率小於1%,接近0%爲好。 
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 MTS 
select busy/(busy+idle) "shared servers busy" from v$dispatcher; 
此值大於0.5時，參數需加大 
select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type=''dispatcher''; 
select count(*) from v$dispatcher; 
select servers_highwater from v$mts; 
servers_highwater接近mts_max_servers時，參數需加大 

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 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、索引的存儲狀況檢查 
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=''&owner'' 
group by segment_name; 

18、找使用CPU多的用戶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.監控log_buffer的使用狀況：(值最好小於1%，不然增長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''; 

21、查看運行過的SQL語句： 
SELECT SQL_TEXT 
FROM V$SQL 

22.oracle等待事件檢測 
 
使用ORACLE的等待事件檢測性能瓶頸
案例分析：以sys用戶登陸 
1.首先從整個系統考慮，找到從系統啓動以來最主要的等待事件是什麼？
SQL>@syssum.sql
2.更爲重要的是，在應用執行的時候，最主要的等待事件是什麼？
SQL>@cr_base.sql
SQL>@in_base.sql
執行用戶應用操做一段時間後
SQL>@re_base.sql
3. 查詢產生等待事件最多的哪些會話？？（以等待事件log file parallel write爲例）
SQL>@seswt.sql log

4.查找哪些語句引發的等待，按照最消耗資源的順序排列顯示
SQL>@sqls1.sql 1000 1000
--以最消耗資源會話13爲例
SQL>@sqlst.sql 13
查找出相關sql語句的地址好比：2168CBB8
SQL>@sqls2.sql 2168CBB8
 

附錄：腳本
--syssum.sql
set linesize 200
col "Wait Event" for a45
select EVENT "Wait Event",TIME_WAITED "Time Waited",
       TIME_WAITED/(SELECT SUM(TIME_WAITED) FROM v$system_event) "%Time waited",
       TOTAL_WAITS "Waits",
       TOTAL_WAITS/(SELECT SUM(TOTAL_WAITS) FROM V$system_event) "%Waited"
from v$system_event
order by 3 desc;

--cr_base.sql
create table sys_b(
event varchar2(64),
time_waited number,
total_waits number);
create table sys_e(
event varchar2(64),
time_waited  number,
total_waits  number);

--in_base.sql
insert into sys_b 
select event,time_waited,total_waits 
from v$system_event;

--re_base.sql
insert into sys_e
select event,time_waited,total_waits
from v$system_event;
create table sys_dif
as
select e.event ,e.time_waited-b.time_waited  TIME_WAITED,
                e.total_waits-b.total_waits  TOTAL_WAITS
from sys_b b,sys_e e
where b.event=e.event;
select event "Wait Event",time_waited "Time Waited",
       time_waited/(select sum(time_waited) from sys_dif) "%Time waited",
       total_waits "Waits",
       total_waits /(select sum(total_waits) from sys_dif) "%Waited"
from sys_dif
order by 3 desc;
drop table sys_dif;
drop table sys_b;
drop table sys_e;
 
等待事件的等待次數
--seswa.sql
select event "Wait Event",
       count(seconds_in_wait) "Waited So Far(sec)",
       count(sid) "Num Sess Waiting"
from v$session_wait
group by event;

--seswt.sql
select sid,event "Wait Event",state "Wait Stat",
       wait_time "W'd So Far(secs)", seconds_in_wait "Time W'd (secs)"
from v$session_wait
where event like '&a'
order by 5;

--sqls1.sql
select * from 
        (select address "Stmt Addr",
                disk_reads "Disk RDS",
                buffer_gets "Buff Gets",
                sorts "Sorts",
                executions "Runs",
                loads "Body Loads"
          from v$sqlarea where disk_reads > &A
          order by disk_reads  )
where rownum < &B;
 
--sqlst.sql
select cpu.sid "SID",cpu.username "USER Name",cpu.value "CPU(sec)",
       reads.value "IO Read(k)",writes.value "IO Write(k)"
from 
(select a.sid sid,a.username username,b.name,c.value value, a.serial# serial#
from v$session a,v$statname b,v$sesstat c
where a.sid=c.sid and b.statistic#=c.statistic# and b.name='CPU used by this session') cpu,
(select a.sid,a.username,b.name,c.value value from v$session a,v$statname b ,v$sesstat c
where a.sid=c.sid and b.statistic#=c.statistic# and b.name='physical reads') reads,
(select a.sid,a.username,b.name,c.value value from v$session a,v$statname b ,v$sesstat c
where a.sid=c.sid and b.statistic#=c.statistic# and b.name='physical writes') writes
where cpu.sid=reads.sid and reads.sid=writes.sid and cpu.username is not null;
 
--sqls2.sql
select sql_text "SQL Statement Text"
from v$sqlarea
where ADDRESS='&a';