dba.txt

DBA具体操作方法以及常见问题解决办法

所以，一直在system表空间上做操作，导致system表空间所在的数据文件SYSTEM01.DBF被读写的次数最多，

这也说明了，尽量不要在system表空间做与系统无关的操作，应给各个用户建立单独的表空间。



44. 查看哪些session正在使用哪些回滚段:

col 回滚段名 format a10

col SID format 9990

col 用户名 format a10

col 操作程序 format a80

col status format a6 trunc



SELECT r.name 回滚段名,

s.sid,

s.serial#,

s.username 用户名,

t.status,

t.cr_get,

t.phy_io,

t.used_ublk,

t.noundo,

substr(s.program, 1, 78) 操作程序

FROM sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r

WHERE t.addr = s.taddr and t.xidusn = r.usn

ORDER BY t.cr_get,t.phy_io;



45.检查谁Lock了什么对象:
set line 200
col "O/S-User" format a10
col "Ora-User" format a10
col "Obj Locked" format a30
select /*+RULE*/s.machine, s.osuser "O/S-User", s.username "Ora-User", s.sid "Session-ID",
s.serial# "Serial", s.process "Process-ID", s.status "Status",l.name "Obj Locked",
l.mode_held "Lock Mode"
from v$session s,dba_dml_locks l,v$process p
where l.session_id = s.sid and p.addr = s.paddr
/
46.造成等待的LOCK的信息，比如LOCK类型等：
col event format a30
set line 160
col machine format a10
col username format a15
select b.sid,b.serial#,b.username,machine,event,wait_time,chr(bitand(p1,-16777216)/16777215)||chr(bitand(p1, 16711680)/65535) "Enqueue Type" from v$session_wait a,v$session b
where event not like 'SQL*N%' and event not like 'rdbms%' and a.sid=b.sid
and b.sid>8 and event='enqueue'
order by username
/



47. List of the locked Oracle objects

set line 120

column object_name format a32

column OS_USER_NAME format a12

column orauser format a12

column sql_text format a32

column serial# format 999999

column sid format 99999

SELECT OS_USER_NAME, ORACLE_USERNAME AS orauser, s.sid, o.object_name,

o.object_type, s.serial#, a.sql_text

FROM v$locked_object l, dba_objects o, v$session s, v$sqlarea a

WHERE l.object_id = o.object_id

AND s.SQL_ADDRESS = a.address

AND l.SESSION_ID = s.sid;

SELECT 'ALTER SYSTEM KILL SESSION '''||TO_CHAR(s.sid)||','||TO_CHAR(s.serial#)||''';'

AS "Statement to kill"

FROM v$locked_object l, dba_objects o, v$session s

WHERE l.object_id = o.object_id

AND l.SESSION_ID = s.sid;





oracle数据库性能监控的SQL

1. 监控事例的等待
SQL>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
SQL>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
SQL>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
SQL>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
SQL>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
SQL>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
SQL>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%
SQL>select sum(pins) "Total Pins", sum(reloads) "Total Reloads",
sum(reloads)/sum(pins) *100 libcache from v$librarycache;
SQL>select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent" from v$librarycache;

9. 显示所有数据库对象的类别和大小
SQL>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%
SQL>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
SQL>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
SQL>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
SQL>SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM V$LIBRARYCACHE;
SQL>SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE" FROM V$ROWCACHE;
SQL>SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE EXECUTING" FROM V$LIBRARYCACHE;(后者除以前者,此比率小于1%,接近0%为好)
SQL>SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES" FROM V$ROWCACHE;

14. 查找ORACLE字符集
SQL>select * from sys.props$ where name='NLS_CHARACTERSET';

15. 监控 MTS
SQL>select busy/(busy+idle) "shared servers busy" from v$dispatcher;
(此值大于0.5时，参数需加大)
SQL>select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type='dispatcher';
SQL>select count(*) from v$dispatcher;
SQL>select servers_highwater from v$mts;
(servers_highwater接近mts_max_servers时，参数需加大)

16. 碎片程度
SQL>select tablespace_name,count(tablespace_name) from dba_free_space group by tablespace_name having count(tablespace_name)>10;
SQL>alter tablespace name coalesce;
SQL>alter table name deallocate unused;
SQL>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;

SQL>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
SQL>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
SQL>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;
SQL>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
SQL>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;

(12是cpu used by this session)



表空间统计

A、 脚本说明：

这是我最常用的一个脚本，用它可以显示出数据库中所有表空间的状态，如表空间的大小、已使用空间、使用的百分比、空闲空间数及现在表空间的最大块是多大。

B、脚本原文:

SELECT upper(f.tablespace_name) "表空间名",

d.Tot_grootte_Mb "表空间大小(M)",

d.Tot_grootte_Mb - f.total_bytes "已使用空间(M)",

to_char(round((d.Tot_grootte_Mb - f.total_bytes) / d.Tot_grootte_Mb * 100,2),'990.99') "使用比",

f.total_bytes "空闲空间(M)",

f.max_bytes "最大块(M)"

FROM

(SELECT tablespace_name,

round(SUM(bytes)/(1024*1024),2) total_bytes,

round(MAX(bytes)/(1024*1024),2) max_bytes

FROM sys.dba_free_space

GROUP BY tablespace_name) f,

(SELECT dd.tablespace_name, round(SUM(dd.bytes)/(1024*1024),2) Tot_grootte_Mb

FROM sys.dba_data_files dd

GROUP BY dd.tablespace_name) d

WHERE d.tablespace_name = f.tablespace_name

ORDER BY 4 DESC;



查看无法扩展的段

A、 脚本说明：

ORACLE 对一个段比如表段或索引无法扩展时，取决的并不是表空间中剩余的空间是多少，而是取于这些剩余空间中最大的块是否够表比索引的“NEXT”值大，所以有时一个表空间剩余几个G的空闲空间，在你使用时ORACLE还是提示某个表或索引无法扩展，就是由于这一点，这时说明空间的碎片太多了。这个脚本是找出无法扩展的段的一些信息。

B、脚本原文：

SELECT segment_name,

segment_type,

owner,

a.tablespace_name "tablespacename",

initial_extent/1024 "inital_extent(K)",

next_extent/1024 "next_extent(K)",

pct_increase,

b.bytes/1024 "tablespace max free space(K)",

b.sum_bytes/1024 "tablespace total free space(K)"

FROM dba_segments a,

(SELECT tablespace_name,MAX(bytes) bytes,SUM(bytes) sum_bytes FROM dba_free_space GROUP BY tablespace_name) b

WHERE a.tablespace_name=b.tablespace_name

AND next_extent>b.bytes

ORDER BY 4,3,1;



查看段(表段、索引段)所使用空间的大小

A、 脚本说明：

有时你可能想知道一个表或一个索引占用多少M的空间，这个脚本就是满足你的要求的，把<>中的内容替换一下就可以了。

B、脚本原文：

SELECT owner,

segment_name,

SUM(bytes)/1024/1024

FROM dba_segments

WHERE owner=

And segment_name=

GROUP BY owner,segment_name

ORDER BY 3 DESC;



查看数据库中的表锁

A、 脚本说明：

这方面的语句的样式是很多的，各式一样，不过我认为这个是最实用的，不信你就用一下，无需多说，锁是每个DBA一定都涉及过的内容，当你相知道某个表被哪个session锁定了，你就用到了这个脚本。

B、脚本原文：

SELECT A.OWNER,

A.OBJECT_NAME,

B.XIDUSN,

B.XIDSLOT,

B.XIDSQN,

B.SESSION_ID,

B.ORACLE_USERNAME,

B.OS_USER_NAME,

B.PROCESS,

B.LOCKED_MODE,

C.MACHINE,

C.STATUS,

C.SERVER,

C.SID,

C.SERIAL#,

C.PROGRAM

FROM ALL_OBJECTS A,

V$LOCKED_OBJECT B,

SYS.GV_$SESSION C

WHERE ( A.OBJECT_ID = B.OBJECT_ID )

AND (B.PROCESS = C.PROCESS )

-- AND

ORDER BY 1,2 ;



处理存储过程被锁

A、 脚本说明：

实际过程中可能你要重新编译某个存储过程理总是处于等待状态，最后会报无法锁定对象，这时你就可以用这个脚本找到锁定过程的那个sid，需要注意的是查v$access这个视图本来就很慢，需要一些布耐心。

B、脚本原文：

SELECT * FROM V$ACCESS

WHERE owner=

And object


?

查看回滚段状态

A、? 脚本说明

这也是DBA经常使用的脚本，因为回滚段是online还是full是他们的关怀之列嘛

??? B、SELECT a.segment_name,b.status

? FROM Dba_Rollback_Segs a,

??????? v$rollstat b

??????? WHERE a.segment_id=b.usn

???????? ORDER BY 2

?? ??????

看哪些session正在使用哪些回滚段

????? A、 脚本说明：

? 当你发现一个回滚段处理full状态，你想使它变回online状态，这时你便会用alter rollback segment rbs_seg_name shrink,可很多时侯确shrink不回来，主要是由于某个session在用，这时你就用到了这个脚本，找到了sid的serial#余下的事就不用我说了吧。

B、脚本原文

?SELECT? r.name 回滚段名,

??? s.sid,

??? s.serial#,

??? s.username 用户名,

??? s.status,

??? t.cr_get,

??? t.phy_io,

??? t.used_ublk,

??? t.noundo,

??? substr(s.program, 1, 78) 操作程序

FROM?? sys.v_$session s,sys.v_$transaction t,sys.v_$rollname r

WHERE? t.addr = s.taddr and t.xidusn = r.usn

?-- AND r.NAME IN ('ZHYZ_RBS')

ORDER? BY t.cr_get,t.phy_io

?

查看正在使用临时段的session

A、 脚本说明：

许多的时侯你在查看哪些段无法扩展时，回显的结果是临时段，或你做表空间统计时发现临段表空间的可用空间几乎为0,这时按oracle的说法是你只有重新启动数据库才能回收这部分空间。实际过程中没那么复杂，使用以下这段脚本把占用临时段的session杀掉，然后用alter tablespace temp coalesce;这个语句就把temp表空间的空间回收回来了。

B、 脚本原文

SELECT username,sid,serial#,sql_address,machine,program,

tablespace,segtype,contents FROM v$session se,v$sort_usage su