ORACLE 12C新特性CDB与PDB

Oracle 12C引入了CDB与PDB的新特性，在ORACLE 12C数据库引入的多租用户环境（Multitenant Environment）中，允许一个数据库容器（CDB）承载多个可插拔数据库（PDB）。CDB全称为Container Database，中文翻译为数据库容器，PDB全称为Pluggable Database，即可

Oracle 12C引入了CDB与PDB的新特性，在ORACLE 12C数据库引入的多租用户环境（Multitenant Environment）中，允许一个数据库容器（CDB）承载多个可插拔数据库（PDB）。CDB全称为Container Database，中文翻译为数据库容器，PDB全称为Pluggable Database，即可插拔数据库。在ORACLE 12C之前，实例与数据库是一对一或多对一关系（RAC）：即一个实例只能与一个数据库相关联，数据库可以被多个实例所加载。而实例与数据库不可能是一对多的关系。当进入ORACLE 12C后，实例与数据库可以是一对多的关系。下面是官方文档关于CDB与PDB的关系图。

 

其实大家如果对SQL SERVER比较熟悉的话，这种CDB与PDB是不是感觉和SQL SERVER的单实例多数据库架构是一回事呢。像PDB$SEED可以看成是master、msdb等系统数据库，PDBS可以看成用户创建的数据库。而可插拔的概念与SQL SERVER中的用户数据库的分离、附加其实就是那么一回事。看来ORACLE也“抄袭”了一把SQL SERVER的概念，只是改头换面的包装了一番。

 

 

CDB组件（Components of a CDB）

 

一个CDB数据库容器包含了下面一些组件：

ROOT组件

ROOT又叫CDB$ROOT, 存储着ORACLE提供的元数据和Common User,元数据的一个例子是ORACLE提供的PL/SQL包的源代码，Common User 是指在每个容器中都存在的用户。

SEED组件

  Seed又叫PDB$SEED,这个是你创建PDBS数据库的模板，你不能在Seed中添加或修改一个对象。一个CDB中有且只能有一个Seed. 这个感念，个人感觉非常类似SQL SERVER中的model数据库。

PDBS

    CDB中可以有一个或多个PDBS，PDBS向后兼容，可以像以前在数据库中那样操作PDBS，这里指大多数常规操作。

这些组件中的每一个都可以被称为一个容器。因此，ROOT(根)是一个容器，Seed(种子)是一个容器，每个PDB是一个容器。每个容器在CDB中都有一个独一无二的的ID和名称。

 

1）连接到CDB数据库

连接到CDB数据库容器非常简单，跟以前连接数据库是一样的

<span>[</span><span>oracle@get-orasvr02 ~</span><span>]</span>$ sqlplus <span>/</span> <span>as</span><span> sysdba

SQL</span><span>*</span>Plus: Release <span><strong>12.1</strong></span>.<span><strong>0.1</strong></span>.<span><strong>0</strong></span> Production <span>on</span> Sun Oct <span><strong>20</strong></span> <span><strong>23</strong></span>:<span><strong>41</strong></span>:<span><strong>36</strong></span> <span><strong>2013</strong></span><span>

Copyright (c) </span><span><strong>1982</strong></span>, <span><strong>2013</strong></span>, Oracle.  <span>All</span><span> rights reserved.

Connected </span><span>to</span><span> an idle instance.

SQL</span><span>></span>

<span>[</span><span>oracle@get-orasvr02 ~</span><span>]</span>$ sqlplus sys<span>/</span>password   <span>as</span><span> sysdba

SQL</span><span>*</span>Plus: Release <span><strong>12.1</strong></span>.<span><strong>0.1</strong></span>.<span><strong>0</strong></span> Production <span>on</span> Sun Oct <span><strong>20</strong></span> <span><strong>23</strong></span>:<span><strong>43</strong></span>:<span><strong>17</strong></span> <span><strong>2013</strong></span><span>

Copyright (c) </span><span><strong>1982</strong></span>, <span><strong>2013</strong></span>, Oracle.  <span>All</span><span> rights reserved.

Connected </span><span>to</span><span> an idle instance.

SQL</span><span>></span>

 

2）查看数据库是否为CDB

SQL<span>></span> <span>select</span> name, decode(cdb, <span>'</span><span>YES</span><span>'</span>, <span>'</span><span>Multitenant Option enabled</span><span>'</span>, <span>'</span><span>Regular 12c Database: </span><span>'</span>) "Multitenant <span>Option</span>" , open_mode, con_id <span>from</span> v$<span>database</span><span>;

NAME      Multitenant </span><span>Option</span><span>                   OPEN_MODE                CON_ID

</span><span>--</span><span>------- -----------------------------   --------------------         ----------</span>
<span>
EPPS      Multitenant </span><span>Option</span> enabled            <span>READ</span> WRITE                  <span><strong>0</strong></span>

 

YES表示该数据库是CDB,如果是NO表示是NO-CDB(普通数据库)

 

3）查看当前容器（Container）

3.1

SQL<span>></span><span> show con_name

CON_NAME

</span><span>--</span><span>----------------------------</span>
<span>
CDB$ROOT

SQL</span><span>></span>

<span><strong>3.2</strong></span><span>

SQL</span><span>></span> <span>select</span> sys_context(<span>'</span><span>userenv</span><span>'</span>, <span>'</span><span>con_name</span><span>'</span>) "Container DB" <span>from</span><span> dual;

Container DB

</span><span>--</span><span>--------------------------------------------------</span>
<span>
CDB$ROOT

SQL</span><span>></span>

 

4）查看CDB容器中的PDBS信息

查看CDB中有多少个pluggable database

SQL<span>></span>  <span>select</span> con_id, dbid, guid, name , open_mode <span>from</span><span> v$pdbs;

    CON_ID       DBID GUID                             NAME                           OPEN_MODE

</span><span>--</span><span>-------- ---------- -------------------------------- ------------------------------ ----------</span>

         <span><strong>2</strong></span> <span><strong>4071321146</strong></span> E89E8DA2866E3157E043DE07A8C09238 PDB$SEED                       <span>READ</span> <span>ONLY</span>

         <span><strong>3</strong></span> <span><strong>1930201447</strong></span><span> E89E9418B882350CE043DE07A8C092B6 PDBEPPS                        MOUNTED

SQL</span><span>></span>

 

5）启动PDB数据库

方式1：

SQL<span>></span> <span>alter</span> pluggable <span>database</span> PDBEPPS <span>open</span><span>;

Pluggable </span><span>database</span><span> altered.

SQL</span><span>></span> <span>select</span> con_id, dbid, guid, name , open_mode <span>from</span><span> v$pdbs;

    CON_ID       DBID GUID                             NAME                           OPEN_MODE

</span><span>--</span><span>-------- ---------- -------------------------------- ------------------------------ ----------</span>

         <span><strong>2</strong></span> <span><strong>4071321146</strong></span> E89E8DA2866E3157E043DE07A8C09238 PDB$SEED                       <span>READ</span> <span>ONLY</span>

         <span><strong>3</strong></span> <span><strong>1930201447</strong></span> E89E9418B882350CE043DE07A8C092B6 PDBEPPS                         <span>READ</span> WRITE

 

方式2：

SQL<span>></span> <span>alter</span> session <span>set</span> container<span>=</span><span>PDBEPPS;

Session altered.

SQL</span><span>></span><span> startup

Pluggable </span><span>Database</span><span> opened.

SQL</span><span>></span>

 

6）关闭PDB数据库

SQL> alter pluggable database PDBEPPS close;

Pluggable database altered.

SQL> select con_id, dbid, guid, name , open_mode from v$pdbs;

    CON_ID       DBID GUID                             NAME                           OPEN_MODE

---------- ---------- -------------------------------- ------------------------------ ----------

         2 4071321146 E89E8DA2866E3157E043DE07A8C09238 PDB$SEED                       READ ONLY

         3 1930201447 E89E9418B882350CE043DE07A8C092B6 PDBEPPS                        MOUNTED

SQL>

 

 

7）在容器间切换

SQL> alter session set container=PDBEPPS;

Session altered.

SQL> show con_name;

CON_NAME

------------------------------

PDBEPPS

SQL>

SQL> alter session set container=CDB$ROOT;

Session altered.

SQL> show con_name;

CON_NAME

------------------------------

CDB$ROOT

参考资料：

http://docs.oracle.com/cd/E16655_01/server.121/e17636/cdb_intro.htm

http://www.orasos.com/4445.html

http://www.oracle-base.com/articles/12c/multitenant-connecting-to-cdb-and-pdb-12cr1.php

http://www.orasos.com/4445.html