📄 oracle基本操作-13.htm
字号:
<body bgcolor="#000000">
<font color="#FFFFFF"> <font color="#009900">监控数据库性能的SQL </font>
<p>1. 监控事例的等待</p>
<p> select event,sum(decode(wait_Time,0,0,1)) "Prev", <br>
sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot" <br>
from v$session_Wait <br>
group by event order by 4;</p>
<p>2. 回滚段的争用情况</p>
<p> select name, waits, gets, waits/gets "Ratio" <br>
from v$rollstat a, v$rollname b <br>
where a.usn = b.usn; </p>
<p>3. 监控表空间的 I/O 比例</p>
<p> select df.tablespace_name name,df.file_name "file",f.phyrds pyr,<br>
f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw<br>
from v$filestat f, dba_data_files df<br>
where f.file# = df.file_id<br>
order by df.tablespace_name;</p>
<p>4. 监控文件系统的 I/O 比例</p>
<p> select substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",
<br>
a.status, a.bytes, b.phyrds, b.phywrts <br>
from v$datafile a, v$filestat b <br>
where a.file# = b.file#; </p>
<p>5.在某个用户下找所有的索引</p>
<p> select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name<br>
from user_ind_columns, user_indexes<br>
where user_ind_columns.index_name = user_indexes.index_name<br>
and user_ind_columns.table_name = user_indexes.table_name <br>
order by user_indexes.table_type, user_indexes.table_name,<br>
user_indexes.index_name, column_position;</p>
<p>6. 监控 SGA 的命中率</p>
<p> select a.value + b.value "logical_reads", c.value "phys_reads",<br>
round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT
RATIO" <br>
from v$sysstat a, v$sysstat b, v$sysstat c<br>
where a.statistic# = 38 and b.statistic# = 39 <br>
and c.statistic# = 40; </p>
<p>7. 监控 SGA 中字典缓冲区的命中率</p>
<p> select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss
ratio",<br>
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"<br>
from v$rowcache <br>
where gets+getmisses <>0<br>
group by parameter, gets, getmisses; </p>
<p>8. 监控 SGA 中共享缓存区的命中率，应该小于1%</p>
<p> select sum(pins) "Total Pins", sum(reloads) "Total Reloads",<br>
sum(reloads)/sum(pins) *100 libcache<br>
from v$librarycache;</p>
<p> select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins)
"reload percent" <br>
from v$librarycache;</p>
<p>9. 显示所有数据库对象的类别和大小</p>
<p> select count(name) num_instances ,type ,sum(source_size) source_size ,<br>
sum(parsed_size) parsed_size ,sum(code_size) code_size ,sum(error_size) error_size,<br>
sum(source_size) +sum(parsed_size) +sum(code_size) +sum(error_size) size_required
<br>
from dba_object_size <br>
group by type order by 2;</p>
<p>10. 监控 SGA 中重做日志缓存区的命中率，应该小于1%</p>
<p> SELECT name, gets, misses, immediate_gets, immediate_misses,<br>
Decode(gets,0,0,misses/gets*100) ratio1,<br>
Decode(immediate_gets+immediate_misses,0,0,<br>
immediate_misses/(immediate_gets+immediate_misses)*100) ratio2<br>
FROM v$latch WHERE name IN ('redo allocation', 'redo copy'); </p>
<p>11. 监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size </p>
<p> SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts
(disk)'); </p>
<p><br>
12. 监控当前数据库谁在运行什么SQL语句</p>
<p> SELECT osuser, username, sql_text from v$session a, v$sqltext b<br>
where a.sql_address =b.address order by address, piece;</p>
<p>13. 监控字典缓冲区</p>
<p> SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM V$LIBRARYCACHE;<br>
SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE"
FROM V$ROWCACHE;<br>
SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE
EXECUTING" FROM V$LIBRARYCACHE; </p>
<p> 后者除以前者,此比率小于1%,接近0%为好。</p>
<p> SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY
CACHE GET MISSES"<br>
FROM V$ROWCACHE</p>
<p>14. 找ORACLE字符集</p>
<p> select * from sys.props$ where name='NLS_CHARACTERSET'; </p>
<p>15. 监控 MTS</p>
<p> select busy/(busy+idle) "shared servers busy" from v$dispatcher;</p>
<p> 此值大于0.5时，参数需加大</p>
<p> select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where
type='dispatcher';<br>
select count(*) from v$dispatcher;<br>
select servers_highwater from v$mts;</p>
<p> servers_highwater接近mts_max_servers时，参数需加大</p>
<p>16. 碎片程度</p>
<p> select tablespace_name,count(tablespace_name) from dba_free_space group by
tablespace_name <br>
having count(tablespace_name)>10;</p>
<p> alter tablespace name coalesce;<br>
alter table name deallocate unused;</p>
<p> create or replace view ts_blocks_v as<br>
select tablespace_name,block_id,bytes,blocks,'free space' segment_name from
dba_free_space<br>
union all<br>
select tablespace_name,block_id,bytes,blocks,segment_name from dba_extents;</p>
<p> select * from ts_blocks_v;</p>
<p> select tablespace_name,sum(bytes),max(bytes),count(block_id) from dba_free_space
<br>
group by tablespace_name;</p>
<p> 查看碎片程度高的表</p>
<p> SELECT segment_name table_name , COUNT(*) extents<br>
FROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY segment_name<br>
HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);</p>
<p>17. 表、索引的存储情况检查</p>
<p> select segment_name,sum(bytes),count(*) ext_quan from dba_extents where <br>
tablespace_name='&tablespace_name' and segment_type='TABLE' group by tablespace_name,segment_name;</p>
<p> select segment_name,count(*) from dba_extents where segment_type='INDEX' and
owner='&owner'<br>
group by segment_name;</p>
<p>18、找使用CPU多的用户session</p>
<p> 12是cpu used by this session</p>
<p> select a.sid,spid,status,substr(a.program,1,40) prog,a.terminal,osuser,value/60/100
value<br>
from v$session a,v$process b,v$sesstat c<br>
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc;<br>
</p>
</font>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -