Please keep in mind till the Transactions are in Undo until then the DB can be restored ..

To take Restore Point ..

SQL> select flashback_on from v$database;

FLASHBACK_ON
——————
NO

SQL> Alter database flashback on;

CREATE RESTORE POINT Jan07_2107;

conn / as sysdba

shutdown immediate;

startup mount;

flashback database to restore point Jan07_2107;

alter database open resetlogs;

desc V$RESTORE_POINT;

select NAME,SCN,STORAGE_SIZE,TIME from V$RESTORE_POINT;

NAME    SCN            STORAGE_SIZE                 TIME
———  ——–   ———————-     ———————————————
TEST     2861296         0                                26-MAR-18 07.45.02.000000000 PM

drop RESTORE POINT TEST;

Guaranteed Restorepoint can be taken using below command :

CREATE RESTORE POINT Jan07_2107 GUARANTEE FLASHBACK DATABASE;