How to Configuring Oracle Flashback

To enable logging for Flashback Database, set the DB_FLASHBACK_RETENTION_TARGET initialization parameter and issue the ALTER DATABASE FLASHBACK ON statement.

SQL> select log_mode from v$database;

LOG_MODE
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ARCHIVELOG

SQL>
 

If is not configured make sure you follow this tutorial before you proceed.

 SQL> connect / as sysdba

 SQL> shutdown immediate

 SQL> startup mount

SQL>alter database flashback on;

SQL> alter database open;

 SELECT NAME, FLASHBACK_ON FROM V$DATABASE;