甜橘子，专注成都网站制作网站设计与营销型网站建设与优化
QQ :532337155
电话：028-86922220
查看那些库的话必须用dba权限登录。登陆后可以通过下面的方法来查看。
创新互联坚信：善待客户，将会成为终身客户。我们能坚持多年，是因为我们一直可值得信赖。我们从不忽悠初访客户，我们用心做好本职工作，不忘初心，方得始终。10余年网站建设经验创新互联是成都老牌网站营销服务商,为您提供成都做网站、网站制作、网站设计、H5技术、网站制作、成都品牌网站建设、小程序开发服务,给众多知名企业提供过好品质的建站服务。
一、查看有哪些库，你的库理解不准确，应该准确来说是表空间，可以通过下面的命令来实现
1
2
3
4
5
6
7
8
9
10
11
12
13
SELECT Total.name "Tablespace Name",
Free_space, (total_space-Free_space) Used_space, total_space
FROM
(select tablespace_name, sum(bytes/1024/1024) Free_Space
from sys.dba_free_space
group by tablespace_name
) Free,
(select b.name, sum(bytes/1024/1024) TOTAL_SPACE
from sys.v_$datafile a, sys.v_$tablespace B
where a.ts# = b.ts#
group by b.name
) Total
WHERE Free.Tablespace_name = Total.name
二、查看有哪些表。
1
select table_name from dba_tables where owner='A';
模式是指数据库对象，是对用户所创建的数据对象的总称。
模式对象包括表、视图、索引、同义词、序列、过程和程序包等
oracle dg 三大模式切换
1、最大性能模式MAXIMUM PERFORMANCE --默认模式，最大性能模式特点。
192.168.1.181
SQL select database_role,protection_mode,protection_level from v$database;
DATABASE_ROLE PROTECTION_MODE PROTECTION_LEVEL
---------------- -------------------- --------------------
PRIMARY MAXIMUM PERFORMANCE MAXIMUM PERFORMANCE
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_config string dg_config=(orcl,db01)
log_archive_dest_1 string location=/home/oracle/arch_orc
l valid_for=(all_logfiles,all_
roles) db_unique_name=orcl
log_archive_dest_2 string service=db_db01 LGWR ASYNC val
id_for=(online_logfiles,primar
y_roles) db_unique_name=db01
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 31
Next log sequence to archive 33
Current log sequence 33
192.168.1.183
SQL select database_role,protection_mode,protection_level from v$database;
DATABASE_ROLE PROTECTION_MODE PROTECTION_LEVEL
---------------- -------------------- --------------------
PHYSICAL STANDBY MAXIMUM PERFORMANCE MAXIMUM PERFORMANCE
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_config string dg_config=(db01,orcl)
log_archive_dest_1 string location=/home/oracle/arch_db0
1 valid_for=(all_logfiles,all_
roles) db_unique_name=db01
log_archive_dest_2 string service=db_orcl LGWR ASYNC val
id_for=(online_logfiles,primar
y_roles) db_unique_name=orcl
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 31
Next log sequence to archive 33
Current log sequence 33
192.168.1.181
SQL alter system switch logfile;
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 32
Next log sequence to archive 34
Current log sequence 34
192.168.1.183
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_db01
Oldest online log sequence 32
Next log sequence to archive 0
Current log sequence 34
2 、最大性能模式--切换到--最大高可用 (默认是最大性能模式---MAXIMUM PERFORMANCE)。
192.168.1.181
SQL select DATABASE_ROLE,PROTECTION_MODE,PROTECTION_LEVEL from v$database;
DATABASE_ROLE PROTECTION_MODE PROTECTION_LEVEL
---------------- -------------------- --------------------
PRIMARY MAXIMUM PERFORMANCE MAXIMUM PERFORMANCE
SQL show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_dest_2 string service=db_db01 LGWR ASYNC val
id_for=(online_logfiles,primar
y_roles) db_unique_name=db01
192.168.1.181
SQL shutdown immediate
192.168.1.183
SQL alter database recover managed standby database cancel;
SQL shutdown immediate
192.168.1.181
SQL startup mount;
SQL alter database set standby database to maximize availability;
SQL alter system set log_archive_dest_2='service=db_db01 LGWR SYNC valid_for=(online_logfiles,primary_roles) db_unique_name=db01' scope=spfile;
192.168.1.183
SQL startup nomount
SQL alter database mount standby database;
SQL alter system set log_archive_dest_2='service=db_orcl LGWR SYNC valid_for=(online_logfiles,primary_roles) db_unique_name=orcl' scope=spfile;
SQL shutdown immediate
SQL startup nomount
SQL alter database mount standby database;
192.168.1.181
SQL startup
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_dest_2 string service=db_db01 LGWR SYNC vali
d_for=(online_logfiles,primary
_roles) db_unique_name=db01
SQL select database_role,protection_level,protection_mode from v$database;
DATABASE_ROLE PROTECTION_LEVEL PROTECTION_MODE
---------------- -------------------- --------------------
PRIMARY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 34
Next log sequence to archive 36
Current log sequence 36
192.168.1.183
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_dest_2 string service=db_orcl LGWR SYNC vali
d_for=(online_logfiles,primary
_roles) db_unique_name=orcl
SQL select database_role,protection_level,protection_mode from v$database;
DATABASE_ROLE PROTECTION_LEVEL PROTECTION_MODE
---------------- -------------------- --------------------
PHYSICAL STANDBY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_db01
Oldest online log sequence 35
Next log sequence to archive 0
Current log sequence 36
192.168.1.181
SQL alter system switch logfile;
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 35
Next log sequence to archive 37
Current log sequence 37
192.168.1.183
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_db01
Oldest online log sequence 36
Next log sequence to archive 0
Current log sequence 37
3、最大高可用--切换到--最保护能模式，DG最大保护模式Maximum protection。
192.168.1.181
SQL shutdown immediate
192.168.1.183
SQL shutdown immediate
192.168.1.181
SQL alter database set standby database to maximize protection;
SQL shutdown immediate
192.168.1.183
SQL startup nomount
SQL alter database mount standby database;
192.168.1.181
SQL startup
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_dest_2 string service=db_db01 LGWR SYNC vali
d_for=(online_logfiles,primary
_roles) db_unique_name=db01
SQL select database_role,protection_level,protection_mode from v$database;
DATABASE_ROLE PROTECTION_LEVEL PROTECTION_MODE
---------------- -------------------- --------------------
PRIMARY MAXIMUM PROTECTION MAXIMUM PROTECTION
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 37
Next log sequence to archive 39
Current log sequence 39
192.168.1.183
SQL col dest_name for a25
SQL select dest_name,status from v$archive_dest_status;
DEST_NAME STATUS
------------------------- ---------
LOG_ARCHIVE_DEST_1 VALID
LOG_ARCHIVE_DEST_2 VALID
SQL show parameter log_archive_dest_2
NAME TYPE VALUE
------------------------------------ ----------- ---------------------------
log_archive_dest_2 string service=db_db01 LGWR SYNC vali
d_for=(online_logfiles,primary
_roles) db_unique_name=db01
SQL select database_role,protection_level,protection_mode from v$database;
DATABASE_ROLE PROTECTION_LEVEL PROTECTION_MODE
---------------- -------------------- --------------------
PRIMARY MAXIMUM PROTECTION MAXIMUM PROTECTION
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_db01
Oldest online log sequence 37
Next log sequence to archive 0
Current log sequence 39
192.168.1.181
SQL alter system switch logfile;
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_orcl
Oldest online log sequence 38
Next log sequence to archive 40
Current log sequence 40
192.168.1.183
SQL archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /home/oracle/arch_db01
Oldest online log sequence 37
Next log sequence to archive 0
Current log sequence 40
引用：
我觉得这里说得还是比较靠谱：
在ORACLE数据库中，
模式对应整个数据库中的表、索引、序列；
外模式对应某个用户的表、索引、序列、视图、同义词，也称为“方案对象”；
内模式对应存储结构，比如逻辑存储结构（表空间、区、段、块等）、物理存储结构（数据文件、控制文件、重做日志文件、初始化参数文件、配置文件等）。
其他数据库类似。
我用了DB2，其中就有模式SCHMEA关键词，但这个概念比较虚，更多人愿意使用OWNER这个关键词。
最大的问题在于电脑不是中国人发明的，数据库概念也不是，模式的词汇是硬翻译过来的。
个人认为模式，就是架构层次的意思，
模式：总体架构及设计方式
外模式：用户层，所有与使用者程序或用户打交道的一系列概念
内模式：存储层，所有与数据存储方式打交道的一系列概念
如果要以视图访问来看，就更典型：
SELECT * FROM 数据库.A视图
A视图纯粹用于用户层
而视图-表-表空间的整体架构就是数据库模式
A视图基于 B，C,D表
B,C,D表又位于b,c,d表空间
那么 A-B,C,D就是外模式到模式的对应， B,C,D=到b,c,d就是模式到内模式的对应
内模式不仅包含表如何存放到表空间，表空间如何在文件上存储，还要关心表空间如何分页、分段、分区等。