这个是我以前在工作中常用的一些SQL语句,里面大部分都是从其他网站上找的,只有部分是自己在工作中解决问题事记录的,现在一起贴出来跟大家分享下,其实很多时候看看别人的经验总结和技术的理解,会使自己少走很多弯路。
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(*)
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
4.监空文件系统的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 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%
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,'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;
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 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
from v$session a,v$process b,v$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by
value desc;
20.监控log_buffer的使用情况:(值最好小于1%,否则增加log_buffer 的大小)
select
rbar.name,rbar.value,re.name,re.value,(rbar.value*100)/re.value'%'
"radio"
from v$sysstat rbar,v$sysstat re
where rbar.name='redo buffer allocation retries'
and re.name='redo entries';
19、查看运行过的SQL语句:
SELECT SQL_TEXT
FROM V$SQL
where executions > 0
order by 4 desc
---------------------
释放undo表空间
1.确认文件
select file_name, bytes/1024/1024 from dba_data_files where
tablespace_name ='UNDOTBS1';
2.检查undo segment状态
select usn, xacts, rssize/1024/1024, hwmsize/1024/1024,shrinks from
v$rollstat order by rssize;
3.创建新undo表空间
create undo tablespace undotbs2 datafile '' size 500m autoextend
on;
4.切换undo表空间为新的undo表空间
alter system set undo_tablespace = undostbs2 scope=both;
5.等待原undo表空间所以undo segment offline;
select usn,xacts, status, rssize/1024/1024,
hwmsize/1024/1024,shrinks from v$rollstat oder by rsszie;
6.删除原undo表空间
drop tablespace undotbs1 including contexns;
1.使用如下语句a查看一下认谁在用临时段
SELECT se.username,
WHERE se.saddr = su.session_addr
2、那些正在使用临时段的进程
Alter system kill session 'sid,serial#';
3、把TEMP表空间回缩一下
Alter tablespace TEMP coalesce;
如何限制oracle中用户的资源的使用(包括连接时间和空闲时间等)
可以创建不同的资源限制,最好将ALTER SYSTEM SET RESOURCE_LIMIT=TRUE
写在init文件中:RESOURCE_LIMIT=TRUE ,不然下次启动可能……
create profile low_limits limit
然后把某种配置文件赋给某个用户:
alter user youruser
然后可以查看:
select profile from dba_users where username='YOURUSER';
select * from dba_profile where profile='low_limits';
其它资源比如:
session_per_user
cpu_per_session
cpu_per_call
private_sga
(1)系统崩溃只剩下数据文件的情况下的恢复,甚至没有system表空间而只有数据表空间的情况下的恢复.只要提供数据文件就可恢复.
(2) undo 、 system 表空间损坏的恢复 .
(3) 非归档或者归档模式下误 delete 数据的恢复、误删除表空间的恢复、 drop 、 truncate 表的恢复
(4) 各种 ora- 错误的修复
(5) DMP 文件不能导入数据库以及 LOB 数据恢复等情况 .
(6) oracle数据库中数据文件出现坏块情况下的恢复.
(7) oracle数据库无数据文件但有有日志的情况下的恢复.
(8) UNIX、WINDOWS下ORACLE数据文件被误删除情况下的数据库恢复.
(9) 磁盘阵列上的ORACLE数据库被误格式化情况下的数据库恢复.
(10) Oracle10G、Oracle11G 的ASM损坏的数据库恢复.
(11)各种版本的ORACLE数据库恢复
delete 数据的恢复
--获取当前SCN
select dbms_flashback.get_system_change_number from dual;
--根据时间点获取SCN
select timestamp_to_scn(to_timestamp('2010-04-27
14:43:00','YYYY-MM-DD HH24:MI:SS')) from dual;
--根据SCN查询表数据
select * from tb as of scn scn_num;
--选出最占用资源的查询
select b.username, a.DISK_READS, a.EXECUTIONS,
a.DISK_READS/decode(a.EXECUTIONS, 0, 1, a.EXECUTIONS)
rds_exec_ratio, a.SQL_TEXT
where a.PARSING_USER_ID = b.user_id
select *
where rank_bufgets < 11;
--查询在定义的时间间隔内(默认15秒)最占用物理读取、CPU使用或逻辑读取的会话
select to_char(a.END_TIME, 'yyyy-mm-dd hh24:mi:ss') e_dttm,