Oracle DBA常用SQL

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.进程监控：

select distinct p.spid unix_process,

s.terminal,

to_char(s.logon_time,‘YYYY/MON/DD HH24:MI‘) Logon_Time,

s.username

from v$process p, v$session s

where p.addr=s.paddr order by 2

 

 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 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;

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

常用用户SQL

表：

select * from cat;

select * from tab;

select table_name from user_tables;

视图：

select text from user_views where view_name=upper(‘&view_name‘);

索引：

select index_name,table_owner,table_name,tablespace_name,status from user_indexes order by

table_name;

触发器：

select trigger_name,trigger_type,table_owner,table_name,status from user_triggers;

快照：

select owner,name,master,table_name,last_refresh,next from user_snapshots order by

owner,next;

同义词：

select * from syn;

序列：

select * from seq;

数据库链路：

select * from user_db_links;

约束限制：

select TABLE_NAME,CONSTRAINT_NAME,SEARCH_CONDITION,STATUS

from user_constraints WHERE TABLE_name=upper(‘&TABLE_Name‘);

本用户读取其他用户对象的权限：

select * from user_tab_privs;

本用户所拥有的系统权限：

select * from user_sys_privs;

用户：

select * from all_users order by user_id;

表空间剩余自由空间情况：

select tablespace_name,sum(bytes) 总字节数,max(bytes),count(*) from dba_free_space group

by tablespace_name；

数据字典：

select table_name from dict order by table_name;

锁及资源信息：

select * from v$lock;不包括DDL 锁