开启数据库闪回功能

--关闭数据库，需要将数据库打开到mount状态才能开启闪回功能：

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> show user

USER is "SYS"

SQL> exit

Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production

With the Partitioning, OLAP and Data Mining options

[lubinsu@localhost oracle]$ sqlplus sys/lubinsu as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on Sat Mar 23 20:14:38 2013

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> show parameter database

ORA-01034: ORACLE not available

SQL> startup nomout

SP2-0714: invalid combination of STARTUP options

SQL> startup nomount

ORACLE instance started.

Total System Global Area  285212672 bytes

Fixed Size                  1218968 bytes

Variable Size              88082024 bytes

Database Buffers          188743680 bytes

Redo Buffers                7168000 bytes

SQL> alter database flashback on

 2  ;

alter database flashback on

*

ERROR at line 1:

ORA-01507: database not mounted

SQL> alter database mount

 2  ;

Database altered.

SQL> alter database flashback on

 2  ;

alter database flashback on

*

ERROR at line 1:

ORA-38706: Cannot turn on FLASHBACK DATABASE logging.

ORA-38707: Media recovery is not enabled.

--需要开启归档才能使用闪回功能

SQL> alter database archivelog on

 2  ;

alter database archivelog on

                         *

ERROR at line 1:

ORA-00933: SQL command not properly ended

SQL> alter database archivelog;

Database altered.

SQL> alter database flashback on;

Database altered.

 

 

SQL> alter database open;

Database altered.

--查看能够闪回的最早的scn号

--如果返回记录为空，说明没有打开闪回功能

SQL> select oldest_flashback_scn from v$flashback_database_log;

OLDEST_FLASHBACK_SCN

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

         1.3161E+13

SQL> select flashback from v$database;

select flashback from v$database

      *

ERROR at line 1:

ORA-00904: "FLASHBACK": invalid identifier

--也可以这么查看是否已经打开闪回功能：

SQL> select flashback_on from v$database;

FLASHBACK_ON

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

YES