监控数据库性能语句
监控数据库性能SQL语句
1. 监控事例等待
select event,
sum(decode(wait_Time,0,0,1)) "Prev",
sum(decode(wait_Time,0,1,0)) "Curr",
count(*) "Tot"
from v$session_Wait
group by event
order by 4;

2. 回滚段争用情况
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 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
order by df.tablespace_name;

4. 监控文件系统 I/O 比例
select substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",
a.status, a.s, 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 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;

7. 监控 SGA 中字典缓冲区命中率
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Cache区命中率应该小于1%
select sum(pins) "Total Pins", sum(reloads) "Total Reloads",
sum(reloads)/sum(pins) *100 libcache
from v$librarycache;
select sum(pinhits-reloads)/sum(pins) "hit radio",
sum(reloads)/sum(pins) "reload percent"
from v$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
from dba_object_size
group by type
order by 1;

10. 监控 SGA 中重做日志缓存Cache区命中率应该小于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,s,blocks,
segment_name
from dba_free_space
union all
select tablespace_name,block_id,s,blocks,
segment_name
from dba_extents;
select * from ts_blocks_v;
select tablespace_name,sum(s),max(s),count(block_id)
from dba_free_space
group by tablespace_name;
查看碎片程度高表
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、索引存储情况检查
select segment_name,sum(s),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;

19.对可疑/性能不好Server Process来进行Trace.,可以用tkprof来分析Trace结果.比较方便.使用UnixKSH.
(1) start_trc:
#!/bin/ksh
(( $# != 1 ))
then
echo Usuage: start_trc pid
fi
sid_serial=$(pr "
connect / as sysdba;
heading off;
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/\([0-9]\{1,\}\)/\1,/' -e '/^$/d' )
[[ -z $sid_serial ]]
then
pr "Seems that this process $1 is not an Oracle process!"
exit 1
fi
pr "
connect / as sysdba;
execute dbms_system._sql_trace_in_session($sid_serial,true);
exit;
" | sqlplus -s /nolog

(2) stop_trc:
#!/bin/ksh
(( $# != 1 ))
then
echo Usuage: stop_trc pid
fi
sid_serial=$(pr "
connect / as sysdba;
heading off;
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/\([0-9]\{1,\}\)/\1,/' -e '/^$/d' )
[[ -z $sid_serial ]]
then
pr "Seems that this process $1 is not an Oracle process!"
exit 1
fi
pr "
connect / as sysdba;
execute dbms_system._sql_trace_in_session($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
FROM v$session sn, v$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
FROM v$lock s
WHERE request != 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||'') 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
from v$lock l, v$session s,
sys.user$ u,sys.obj$ t
where l.sid = s.sid and
s.type != 'BACKGROUND' and
t.obj# = l.id1 and