flashback (1)

1.开启10g的数据库闪回特征

a.确定当前的模式：

SQL> select flashback_on from v$database;

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

SQL> show parameter db_recovery

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest                string      /oracle/product/10.2.0/db_1/fl
                                                 ash_recovery_area
db_recovery_file_dest_size           big integer 2G

SQL> show parameter db_flashback_retention_target;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_flashback_retention_target        integer     1440

b.启用flash database选项：

SQL> shutdown immediate;

      
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.

Total System Global Area  167772160 bytes
Fixed Size                  1279120 bytes
Variable Size             104860528 bytes
Database Buffers           58720256 bytes
Redo Buffers                2912256 bytes
Database mounted.

SQL> alter database flashback on;

alter database flashback on
*
ERROR at line 1:
ORA-38706: Cannot turn on FLASHBACK DATABASE logging.
ORA-38707: Media recovery is not enabled.

 

--可以看到，flashback还必须要归档的保证

SQL> archive log list;

Database log mode              No Archive Mode
Automatic archival             Disabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     17
Current log sequence           19

 

SQL> alter database archivelog;

Database altered.  

  

SQL> alter database flashback on;

Database altered.

SQL> archive log list;

Database log mode              Archive Mode
Automatic archival             Enabled
Archive destination            USE_DB_RECOVERY_FILE_DEST
Oldest online log sequence     17
Next log sequence to archive   19
Current log sequence           19

 

SQL> alter database open;

Database altered.