Convert Physical Standby database into snapshot standby database .

We can open  standby database in read-write mode .When switched back into standby mode, all changes made whilst in read-write mode are lost is know as Snapshot standby database .

Priversly This is achieved using flashback database, but from 11g standby database does not need to have flashback database explicitly enabled to take advantage

of this feature, thought it works just the same if it is.

How To Set Up Physical Standby Database You Can Check Here 

                     http://adminoracle10g.blogspot.in/2014/08/physical-standby-database-implementation.html        

Steps

            1)      Bring database in mount state

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

2)      Disable  recovery  on standby

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

3)      Convert standby database to flashback

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

4)      Open database

ALTER DATABASE OPEN;

5)      Check  database status

Select NAME, OPEN_MODE, DATABASE_ROLE from v$database;

NAME          OPEN_MODE            DATABASE_ROLE

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

ORCL_STBY        READ WRITE    SNAPSHOT STANDBY

SELECT flashback_on FROM v$database;

FLASHBACK_ON

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

RESTORE POINT ONLY

6)      To convert it back to the physical standby, losing all the changes made since the conversion to snapshot standby, issue the following commands.

SHUTDOWN IMMEDIATE;

STARTUP MOUNT;

ALTER DATABASE CONVERT TO PHYSICAL STANDBY;

SHUTDOWN IMMEDIATE;

STARTUP NOMOUNT;

ALTER DATABASE MOUNT STANDBY DATABASE;

ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT;

SELECT flashback_on FROM v$database;

Select NAME, OPEN_MODE, DATABASE_ROLE from v$database;

NAME                  OPEN_MODE            DATABASE_ROLE

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

ORCL_STBY        READ WRITE           PYSICAL STANDBY

FLASHBACK_ON

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

NO