下面是一些监控数据库性能的语句，希望对大家有帮助：
监控数据库性能的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"
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$rollname b
where a.usn = b.usn;
3. 监控表空间的 I/O 比例
select df.tablespace_name name,df.file_name "file",f.phyrds pyr,
f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw
from v$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$librarycache;
select sum(pinhits-reloads)/sum(pins) "hit radio",
sum(reloads)/sum(pins) "reload percent"
from v$librarycache;
9. 显示所有数据库对象的类别和大小
select 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,
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;
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=$1;
exit;
" sqlplus -s /nolog grep -v 'Connected' sed -e 's//([0-9]/{1,/}/)//1,/' -e '/^$/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=$1;
exit;
" sqlplus -s /nolog grep -v 'Connected' sed -e 's//([0-9]/{1,/}/)//1,/' -e '/^$/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 /
