转: http://hi.baidu.com/windy8848/blog/item/3844fef25e7a8114b07ec51e.html
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$session_wait
group by event order by 4;
2.回滚段的争用情况：
select name,waits,gets,waits/gets ratio from v$rollstat a,v$rollname b where a.usn=b.usn;
3.监控表空间的I/O比例：
col name format a10
col file format a50
select df.tablespace_name name,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrts pyw,
f.phyblkwrt pbw
from v$filestat f,dba_data_files df
where f.file#=df.file_id
4.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$sysstat d
where a.name='physical reads' and
b.name='physical reads direct' and
c.name='physical reads direct (lob)' and
d.name='session logical reads';
7. 监控 SGA 中字典缓冲区的命中率
select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"
from v$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$librarycache;
#I f the reloads-to-pins ratio is greater than 1%,increase the value of the SHARED_POOL_SIZE parameter.
来自OCP9i教材
select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent"
from v$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$LIBRARYCACHE;
后者除以前者,此比率小于1%,接近0%为好。
SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
FROM V$ROWCACHE
14. 找ORACLE字符集
select * from sys.props$ where name=''NLS_CHARACTERSET'';
15. 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
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$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc;
20.监控log_buffer的使用情况：(值最好小于1%，否则增加log_buffer 的大小)
select rbar.name,rbar.value,re.name,re.value,(rbar.value*100)/re.value||''%'' "radio"
from v$sysstat rbar,v$sysstat re
where rbar.name=''redo buffer allocation retries''
and re.name=''redo entries'';
21、查看运行过的SQL语句：
SELECT SQL_TEXT
FROM V$SQL
22.
oracle等待事件检测
使用ORACLE的等待事件检测性能瓶颈
案例分析：以sys用户登录
1.首先从整个系统考虑，找到从系统启动以来最主要的等待事件是什么？
SQL>@syssum.sql
2.更为重要的是，在应用执行的时候，最主要的等待事件是什么？
SQL>@cr_base.sql
SQL>@in_base.sql
执行用户应用操作一段时间后
SQL>@re_base.sql
3. 查询产生等待事件最多的哪些会话？？（以等待事件log file parallel write为例）
SQL>@seswt.sql log
4.查找哪些语句引起的等待，按照最消耗资源的顺序排列显示
SQL>@sqls1.sql 1000 1000
--以最消耗资源会话13为例
SQL>@sqlst.sql 13
查找出相关sql语句的地址比如：2168CBB8
SQL>@sqls2.sql 2168CBB8
附录：脚本
--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$system_event;
create table sys_dif
as
select e.event ,e.time_waited-b.time_waited TIME_WAITED,
e.total_waits-b.total_waits TOTAL_WAITS
from sys_b b,sys_e e
where b.event=e.event;
select event "Wait Event",time_waited "Time Waited",
time_waited/(select sum(time_waited) from sys_dif) "%Time waited",
total_waits "Waits",
total_waits /(select sum(total_waits) from sys_dif) "%Waited"
from sys_dif
order by 3 desc;
drop table sys_dif;
drop table sys_b;
drop table sys_e;
等待事件的等待次数
--seswa.sql
select event "Wait Event",
count(seconds_in_wait) "Waited So Far(sec)",
count(sid) "Num Sess Waiting"
from v$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';