FLASHBACK


SQL> select flashback_on from v$database;
 
FLASHBACK_ON
------------------
NO
 
SQL> alter database flashback ON;
alter database flashback ON
*
ERROR at line 1:
ORA-38759: Database must be mounted by only one instance 
and not open.
 
SQL> shut immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
 
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.
 
SQL> alter database archivelog;
 
Database altered.
 
SQL> alter database flashback ON;
 
Database altered.
 
SQL> select flashback_on from v$database;
 
FLASHBACK_ON
------------------
YES
 
4)Open the database and optionally you can set 
DB_FLASHBACK_RETENTION_TARGET to the length of the 
desired flashback window in minutes. By default it 
is 1 day(1440 minutes).
 
SQL> ALTER DATABASE OPEN;
 
To make it 3 days
 
SQL> alter database open;
 
Database altered.
 
SQL> alter system set db_flashback_retention_target=4320;
 
System altered.
SQL> show parameter db_flashback_retention_target
 
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_flashback_retention_target        integer     4320

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