Enabling / Disabling Flashback Database in 11gR2 without recycling database

Flashback database offer a simple way for performing a point in time recovery. This feature was introduced in oracle 10g.

Let’s take a scenario, where we have generated huge amount of flashback logs. Now to reclaim the space, we can reduce the db_flashback_retention_target parameter to a very small value, which will make the logs obsolete after some time & will delete them in case of space pressure in FRA (Flash / Fast Recovery Area).

But if we want to reclaim the space immediately, we can trun off the flashback.

In 10g we’ll have to

shutdown immediate 
startup mount 
alter database flashback off; 
alter database open;

But with 11gR2, Oracle introduced a new feature. We can now turn flashback on / off, when database is OPEN

SQL> select * from v$version;
BANNER
------------------------------------------------------
Oracle Database 11g Enterprise Edition 
Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE 11.2.0.3.0 Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

SQL> select flashback_on, status from v$database, v$instance;
FLASHBACK_ON STATUS
------------------ ------------
YES OPEN

SQL> alter database flashback off;
Database altered.

SQL> select flashback_on, status from v$database, v$instance;
FLASHBACK_ON STATUS
------------------ ------------
NO OPEN

SQL> alter database flashback on;
Database altered.

SQL> select flashback_on, status from v$database, v$instance;
FLASHBACK_ON STATUS
------------------ ------------
YES OPEN