閃回的開啟與關閉

（****使用閃回技術、首先要設置閃回恢復區）
設置快速恢復區的地址
SQL> alter system set db_recovery_file_dest='/u01/app/oracle/'scope=both;

System altered.

SQL>
設置快速恢復區的大小

SQL> alter system set db_recovery_file_dest_size=4G scope=both;

System altered
查看快速恢復區的狀態
SQL> show parameter db_recovery_file_dest

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest                string      /u01/app/oracle/
db_recovery_file_dest_size           big integer 4G
SQL>

{必須在歸檔模式下、而且關閉和開啟數據庫是在mount狀態下}
SQL> archive log list;
Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            /u01/app/oracle/product/11.2.0/dbhome_1/dbs/arch
Oldest online log sequence     12
Next log sequence to archive   14
Current log sequence           14
查看數據庫的閃回是否開啟
SQL> select flashback_on from V$database;

FLASHBACK_ON
------------------
NO

SQL>
首先要開啟數據庫閃回
（1）要在mount狀態下
SQL> alter database flashback on;

Database altered.

SQL>
啟動到open下
SQL> alter database open;

Database altered.
查看閃回狀態
SQL> select flashback_on from v$database;

FLASHBACK_ON
------------------
YES

SQL>
關閉閃回
（1）先關閉數據庫 啟動到mount狀態
SQL> shutdown immediate

Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> SQL>        
SQL> startup mount
ORACLE instance started.

Total System Global Area  835104768 bytes
Fixed Size                  2257840 bytes
Variable Size             541068368 bytes
Database Buffers          289406976 bytes
Redo Buffers                2371584 bytes
Database mounted.
（2)關閉數據庫閃回
SQL> alter database  flashback off;

Database altered.
（3）數據庫open
SQL> alter database open;

Database altered.
(4)查看數據庫閃回狀態

SQL> select flashback_on from v$database;

FLASHBACK_ON
------------------
NO