升级环境：
1、RAC 11.2.0.1 to RAC 11.2.0.2
2、RAC 11.2.0.1 to RAC 11.2.0.3
3、RAC 11.2.0.2 to RAC 11.2.0.3
以上DB软件均是通过out-of-place upgrade方法升级。
如果在升级完成后，发现升级过程有问题，需要回退，我们可以选择两种回退办法：
1. 通过闪回数据库的办法还原到11.2.0.1 /11.2.0.3的数据库
2. 执行catdwgrd.sql 降级数据字典
以下我们介绍通过闪回数据库的办法还原到11.2.0.1 /11.2.0.3的数据库
关于执行catdwgrd.sql 降级数据字典详见：How To Downgrade From Database 11.2 To Previous Release (includes 11.2.0.3-11.2.0.1) [ID883335.1]
一、检查已升级的数据库版本（11.2.0.3）
备注：
我们在升级11.2.0.3的数据字典之前已经做了数据库的闪回点
create restore point upgrade_rollback guarantee flashback database;
SQL> SELECT NAME, SCN, TIME, DATABASE_INCARNATION#, GUARANTEE_FLASHBACK_DATABASE, STORAGE_SIZE FROM V$RESTORE_POINT WHERE GUARANTEE_FLASHBACK_DATABASE='YES';
NAME
--------------------------------------------------------------------------------
SCN
----------
TIME
---------------------------------------------------------------------------
DATABASE_INCARNATION# GUA STORAGE_SIZE
--------------------- --- ------------
UPGRADE_ROLLBACK
1227989
31-MAR-12 10.21.06.000000000 AM
1 YES 16384000
检查版本信息
SQL> select * from global_name;
GLOBAL_NAME
--------------------------------------------------------------------------------
RACDB
SQL> select * from v$version;
SQL> col COMP_ID format a10
SQL> col COMP_NAME format a30
SQL> select comp_id,comp_name,version,status,modified from dba_registry
SQL> /
COMP_ID COMP_NAME VERSION STATUS MODIFIED
---------- ------------------------------ ------------------------------ ---------------------- -----------------------
APEX Oracle Application Express 3.2.1.00.12 INVALID 31-MAR-2012 12:04:14
EM Oracle Enterprise Manager 11.2.0.3.0 VALID 31-MAR-2012 11:36:51
ORDIM Oracle Multimedia 11.2.0.3.0 VALID 31-MAR-2012 12:04:14
XDB Oracle XML Database 11.2.0.3.0 VALID 31-MAR-2012 12:04:13
EXF Oracle Expression Filter 11.2.0.3.0 VALID 31-MAR-2012 12:04:12
RUL Oracle Rules Manager 11.2.0.3.0 VALID 31-MAR-2012 12:04:13
OWM Oracle Workspace Manager 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
CATALOG Oracle Database Catalog Views 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
CATPROC Oracle Database Packages and T 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
ypes
JAVAVM JServer JAVA Virtual Machine 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
XML Oracle XDK 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
CATJAVA Oracle Database Java Packages 11.2.0.3.0 VALID 31-MAR-2012 12:04:11
RAC Oracle Real Application Cluste 11.2.0.3.0 VALID 31-MAR-2012 12:04:14
rs
13 rows selected.