Oracle Flashback provides an additional layer of data protection. You can use flashback features to view past states of data and rewind your database without restoring backups or performing point-in-time recovery. 

You can undo user-errors such as accidental deletion of data, deleting the wrong data, and dropping the wrong table using oracle flashback features.

Oracle Flashback provides following features.

  1. Flashback Database
  2. Flashback Table
  3. Flashback Drop
  4. Flashback Query
  5. Flashback Versions Query
  6. Flashback Transaction Query
  7. Flashback Transaction

Most of the oracle flashback features operate at the logical level, enabling you to view and manipulate database objects. These features do not depend on RMAN With the exception of Flashback Drop, the logical flashback features rely on undo data, which are records of the effects of each database update and the values overwritten in the update.

Flashback Drop is built around a mechanism called the Recycle Bin, which Oracle uses to manage dropped database objects until the space they occupied is needed to store new data.

1. Flashback Database

Oracle flashback database enables you to wind your entire database backward in time, reversing the effects of unwanted database changes within a given time window. It does not require you to restore datafiles from backup. For more details see Flashback Database

  • Flashback Database uses its own logging mechanism, called flashback logs which are stored in the flash recovery area.
  • Oracle flashback is alternative and faster than Point-in-Time Recovery (DBPITR).
  • Oracle Database also supports restore points. A restore point is an alias corresponding to a system change number (SCN). For more details see Restore Points

2. Flashback Table

Flashback table feature returns a table to its state at a previous point in time. You can restore table data while the database is online, undoing changes only to the specified table. Flashback Table restores tables while automatically maintaining associated attributes such as current indexes, triggers, and constraints. For more details see Flashback Table

3. Flashback Drop

Oracle flashback drop feature reverses the effects of a DROP TABLE statement. Flashback Drop is built around a mechanism called the Recycle Bin, which Oracle uses to manage dropped database objects until the space they occupied is needed to store new data.

Flashback Drop is faster than other recovery mechanisms, such as point-in-time recovery, and does not lead to any loss of recent transactions or downtime.

When you drop a table, the database does not immediately remove the space associated with the table. Instead, the table is renamed and, along with any associated objects, it is placed in the Recycle Bin of the database. The Flashback Drop operation recovers the table from the recycle bin. For more details see Flashback Drop

4. Flashback Query

Oracle flashback query feature lets you specify a target time and then run queries against your database. A user could choose a target time before the error and run a query to retrieve the contents of the lost rows. For more details see Flashback Query

5. Flashback Versions Query

Oracle Flashback version query feature lets you view all the versions of all the rows that ever existed in one or more tables in a specified time interval. You can also retrieve metadata about the differing versions of the rows. This feature can be used both to recover lost data values and to audit changes to the tables queried. 

6. Flashback Transaction Query

Oracle flashback transaction query feature enable you to view changes made by a single transaction, or by all the transactions during a period of time. 

7.Flashback Transaction

You can reverse a transaction. Oracle Database determines the dependencies between transactions and in effect creates a compensating transaction that reverses the unwanted changes.

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