DBA常用的一些性能优化方面的SQL语句
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(*) "Tot"
fromv$session_Wait
group by event
order by 4;
2. 回滚段的争用情况
select name, waits, gets, waits/gets "Ratio"
fromv$rollstat a, v$rollname b
wherea.usn = b.usn;
3. 监控表空间的 I/O 比例
select df.tablespace_name name,df.file_name "file",f.phyrds pyr,
f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw
fromv$filestat f, dba_data_files df
wheref.file# = df.file_id
order by df.tablespace_name;
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
fromv$datafile a, v$filestat b
wherea.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
fromuser_ind_columns, user_indexes
whereuser_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"
fromv$sysstat a, v$sysstat b, v$sysstat c
wherea.statistic# = 38 and b.statistic# = 39 and
c.statistic# = 40;
7. 监控 SGA 中字典缓冲区的命中率
select parameter, gets,Getmisses ,
getmisses/(gets+getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"
fromv$rowcache
wheregets+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
fromv$librarycache;
select sum(pinhits-reloads)/sum(pins) "hit radio",
sum(reloads)/sum(pins) "reload percent"
fromv$librarycache;
9. 显示所有数据库对象的类别和大小
select type,
count(name) num_instances,
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
fromdba_object_size
group by type
order by 1;
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
FROMv$latch
WHEREname IN ('redo allocation', 'redo copy');
11.监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size
SELECT name, value
FROMv$sysstat
WHEREname 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
fromv$session a, v$sqltext b
wherea.sql_address =b.address order by address, piece;
13. 监控字典缓冲区
SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE"
FROMV$LIBRARYCACHE;
SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE"
FROMV$ROWCACHE;
SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE EXECUTING"
FROMV$LIBRARYCACHE;
后者除以前者,此比率小于1%,接近0%为好。
SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
FROMV$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)
fromdba_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,
segment_name
fromdba_free_space
union all
select tablespace_name,block_id,bytes,blocks,
segment_name
fromdba_extents;
select * from ts_blocks_v;
select tablespace_name,sum(bytes),max(bytes),count(block_id)
fromdba_free_space
group by tablespace_name;
查看碎片程度高的表
SELECT segment_name table_name , COUNT(*) extents
FROMdba_segments
WHEREowner 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
fromdba_extents
where tablespace_name='&tablespace_name' and
segment_type='TABLE'
group by tablespace_name,segment_name;
select segment_name,count(*)
fromdba_extents
wheresegment_type='INDEX' and wner='&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
fromv$session a,v$process b,v$sesstat c
wherec.statistic#=12 and
c.sid=a.sid and
a.paddr=b.addr
order by value desc;
19.对可疑/性能不好的Server Process来进行Trace.,可以用tkprof来分析Trace的结果.比较方便.使用Unix的KSH.
(1) start_trc:
#!/bin/ksh
if (( $# != 1 ))
then
echo Usuage: start_trc pid
fi
sid_serial=$(print "
connect / as sysdba;
set heading off;
set feedback off;
select a.sid,a.serial# from v\$session a,v\$process b where a.paddr=b.addr and b.spid=$1;
exit;
" | sqlplus -s /nolog | grep -v 'Connected' | sed -e 's/\(\{1,\}\)/\1,/' -e '/^$/d' )
if [[ -z $sid_serial ]]
then
print "Seems that this process $1 is not an Oracle process!"
exit 1
fi
print "
connect / as sysdba;
execute dbms_system.set_sql_trace_in_session($sid_serial,true);
exit;
" | sqlplus -s /nolog
(2) stop_trc:
#!/bin/ksh
if (( $# != 1 ))
then
echo Usuage: stop_trc pid
fi
sid_serial=$(print "
connect / as sysdba;
set heading off;
set feedback off;
select a.sid,a.serial# from v\$session a,v\$process b where a.paddr=b.addr and b.spid=$1;
exit;
" | sqlplus -s /nolog | grep -v 'Connected' | sed -e 's/\(\{1,\}\)/\1,/' -e '/^$/d' )
if [[ -z $sid_serial ]]
then
print "Seems that this process $1 is not an Oracle process!"
exit 1
fi
print "
connect / as sysdba;
execute dbms_system.set_sql_trace_in_session($sid_serial,false);
exit;
" | sqlplus -s /nolog
20.查看Lock
SELECT sn.username, m.sid, m.type,
DECODE(m.lmode, 0, 'None',
1, 'Null',
2, 'Row Share',
3, 'Row Excl.',
4, 'Share',
5, 'S/Row Excl.',
6, 'Exclusive',
lmode, ltrim(to_char(lmode,'990'))) lmode,
DECODE(m.request,0, 'None',
1, 'Null',
2, 'Row Share',
3, 'Row Excl.',
4, 'Share',
5, 'S/Row Excl.',
6, 'Exclusive',
request, ltrim(to_char(m.request,'990'))) request,
m.id1, m.id2
FROMv$session sn, v$lock m
WHERE(sn.sid = m.sid AND m.request != 0) OR
( sn.sid = m.sid AND
m.request = 0 AND
lmode != 4 AND
(id1, id2) IN (
SELECT s.id1, s.id2
FROMv$lock s
WHERErequest != 0 AND
s.id1 = m.id1 AND
s.id2 = m.id2
)
)
ORDER BY id1, id2, m.request;
select l.sid,s.serial#,s.username,s.terminal,
decode(l.type,'RW','RW - Row Wait Enqueue',
'TM','TM - DML Enqueue',
'TX','TX - Trans Enqueue',
'UL','UL - User',l.type||'System') res,
substr(t.name,1,10) tab,u.name owner,
l.id1,l.id2,
decode(l.lmode,1,'No Lock',
2,'Row Share',
3,'Row Exclusive',
4,'Share',
5,'Shr Row Excl',
6,'Exclusive',null) lmode,
decode(l.request,1,'No Lock',
2,'Row Share',
3,'Row Excl',
4,'Share',
5,'Shr Row Excl',
6,'Exclusive',null) request
fromv$lock l, v$session s,
sys.user$ u,sys.obj$ t
wherel.sid = s.sid and
s.type != 'BACKGROUND' and
t.obj# = l.id1 and
u.user# = t.owner#;
監控登入登出的用戶:
創建如下的兩張表:
create table login_log -- 登入登出信息表
(
session_id int not null, -- sessionid
login_on_timedate, -- 登入時間
login_off_timedate, -- 登出時間
user_in_db varchar2(30), -- 登入的db user
machine varchar2(20), -- 機器名
ip_address varchar2(20), -- ip地址
run_program varchar2(20) -- 以何程序登入
);
create table allow_user -- 網域用戶表
(
ip_address varchar2(20), -- ip地址
login_user_name nvarchar2(20) -- 操作者姓名
);
創建如下的兩個觸發器:
create or replace trigger login_on_info -- 紀錄登入信息的觸發器
after logon on database
Begin
insert into login_log(session_id,login_on_time,login_off_time,user_in_db,machine,ip_address,run_program)
select AUDSID,sysdate,null,sys.login_user,machine,SYS_CONTEXT('USERENV','IP_ADDRESS'),program
from v$session where AUDSID = USERENV('SESSIONID');--當前SESSION
END;
create or replace trigger login_off_info -- 紀錄登出信息的觸發器
before logoff on database
Begin
update login_log setlogin_off_time = sysdate
where session_id = USERENV('SESSIONID'); --當前SESSION
exception
when others then
null;
END;
方法二:
用如下的方式可以審計執行drop動作的事件:
/**
* drop語句的審計日誌表
*/
create table drop_log
(
session_id int not null, -- sessionid
drop_timedate, -- drop的時間
ip_address varchar2(20), -- ip地址
object_owner varchar2(30), -- 對象的擁有者
object_name varchar2(30), -- 對象名稱
object_type varchar2(20), -- 對象類型
drop_by_user varchar2(30) -- 執行drop語句的用戶
);
create or replace trigger drop_info
after drop on mfg0513user.schema -- 在mfg0513user用戶上創建審計drop的觸發器
begin
insert into drop_log
(session_id,
drop_time,
ip_address,
object_owner,
object_name,
object_type,
drop_by_user)
values(USERENV('SESSIONID'),
sysdate,
SYS_CONTEXT('USERENV','IP_ADDRESS'),
sys.dictionary_obj_owner,
sys.dictionary_obj_name,
sys.dictionary_obj_type,
sys.login_user);
end;
收藏下~~慢慢看~ 视图，要好好的学呀 ........ 收藏！！！ 太经典了，谢谢老相！ 要好好的学呀 thanks for share! 這個很強大啊，收藏 谢谢相老师，收藏了！ 谢谢相老师~~
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