基于版本：19c （12.2.0.3） AskScuti
主题：可刷新PDB如何进行切换操作
内容说明：本篇延续如何克隆可刷新的PDB（Refreshable PDB）一文，进行切换实验。
具体请参考《克隆可刷新的PDB》
内容总览
1. 环境概述
2. 如何刷新PDB
2.1 连接要刷新PDB所在的根容器
2.2 关闭要刷新的PDB
2.3 执行刷新
2.4 只读模式打开可刷新的PDB（或保留关闭状态）
3. 如何切换可刷新PDB
3.1 检查目标库环境
3.2 目标库创建用户并授权
3.3 源库编辑TNS
3.4 源库创建DBLink
3.5 源PDB与目标PDB进行切换
4. ORA-12754 的说明
1. 环境概述
具体请参考：如何克隆可刷新的PDB（Refreshable PDB）一文。
2. 如何刷新PDB
要刷新一个PDB，前提：该PDB必须是以包含REFRESH MODE MANUAL 或者 REFRESH MODE EVERY minutes 子句克隆出来的PDB。
2.1 连接要刷新PDB所在的根容器
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- --------- ---------- ----------
2 PDB$SEED READ ONLY NO
3 PDB1 MOUNTED
4 PDB_REF READ ONLY NO
5 PDB_REFAUTO MOUNTED
2.2 关闭要刷新的PDB
SQL> alter pluggable database pdb_ref close immediate; Pluggable database altered.
2.3 执行刷新
SQL> alter pluggable database pdb_ref refresh; Pluggable database altered.
2.4 只读模式打开可刷新的PDB（或保留关闭状态）
SQL> alter pluggable database pdb_ref open read only; Pluggable database altered.
3. 如何切换可刷新PDB
可以切换源PDB和可刷新PDB的身份角色。
需要注意的是
- 切换命令必须在源PDB中执行（ALTER PLUGGABLE DATABASE ... SWITCHOVER）；
- 源库和可刷新库不在同一个CDB中时，两个CDB中DBLink指定的用户和密码必须完全一致；
- DBLink中的字符串必须指向PDB所在的根容器中。
3.1 检查目标库环境
[oracle@erp ~]$ rlwrap sqlplus / as sysdba
SQL*Plus: Release 19.0.0.0.0 - Production on Sat Aug 31 21:10:03 2019
Version 19.3.0.0.0
Copyright (c) 1982, 2019, Oracle. All rights reserved.
Connected to:
Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Version 19.3.0.0.0
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- --------- ---------- ----------
2 PDB$SEED READ ONLY NO
3 PDB1 MOUNTED
4 PDB_REF READ ONLY NO
5 PDB_REFAUTO MOUNTED
3.2 目标库创建用户并授权
注意和源库一致
SQL> create user c##u1 identified by oracle; User created. SQL> grant create session,create pluggable database,sysoper to c##u1 container=all; Grant succeeded.
3.3 源库编辑TNS
CDB1 =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.12)(PORT = 1521))
)
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = CDB1)
)
)
3.4 源库创建DBLink
SQL> create database link cdb1_dblink connect to c##u1 identified by oracle using 'CDB1'; Database link created. SQL> select * from tab@cdb1_dblink; no rows selected
3.5 源PDB与目标PDB进行切换
切换前，看下源PDB的状态
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- --------- ---------- ----------
3 ERP1 READ WRITE NO <--- STATUS:READ WRITE
切换前，看下目标PDB的状态
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- --------- ---------- ----------
2 PDB$SEED READ ONLY NO
3 PDB1 MOUNTED
4 PDB_REF READ ONLY NO <--- STATUS:READ ONLY 只读
5 PDB_REFAUTO MOUNTED
在源数据库ERP1中执行切换命令
SQL> alter session set container=erp1;
Session altered.
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- --------- ---------- ----------
3 ERP1 READ WRITE NO
SQL> alter pluggable database refresh mode manual from pdb_ref@cdb1_dblink switchover;
Pluggable database altered.
切换后，看下源PDB状态
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ---------- ---------- ----------
3 ERP1 MOUNTED <--- 注意：由切换前的读写状态，变为了关闭状态（源库ERP1变为可刷新PDB）
切换后，看下目标PDB状态
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ---------- ---------- ----------
2 PDB$SEED READ ONLY NO
3 PDB1 MOUNTED
4 PDB_REF READ WRITE NO <--- 注意：由切换前的只读状态，变为了读写状态（目标PDB变为源PDB）
5 PDB_REFAUTO MOUNTED
最后以只读模式打开可刷新PDB - ERP1
SQL> alter pluggable database erp1 open read only;
Pluggable database altered.
SQL> show pdbs
CON_ID CON_NAME OPEN MODE RESTRICTED
---------- ---------- ---------- ----------
3 ERP1 READ ONLY NO
4. ORA-12754 的说明
如果环境是非Oracle Cloud使用，在执行 ALTER PLUGGABLE DATABASE refresh_mode FROM clonepdb@dblink SWITCHOVER; 命令时，将提示错误：
ERROR at line 1: ORA-12754: Feature PDB REFRESH SWITCHOVER is disabled due to missing capability
因为功能受到限制，作为学习测试使用，您可以自行通过某些方法进行解决，但请勿侵犯Oracle软件版权。