1Z0-062 Question #154: Real Exam Question with Answer & Explanation

Question

Options

• AFlashback logs are written sequentially, and are archived.
• BFlashback Database uses a restored control file to recover a database.
• CThe Oracle database automatically creates, deletes, and resides flashback logs in the Fast
• DFlashback Database can recover a database to the state that it was in before a reset logs
• EFlashback Database can recover a data file that was dropped during the span of time of the
• FFlashback logs are used to restore to the blocks' before images, and then the redo data may be

Explanation

Flashback Database Flashback Database is similar to conventional point-in-time recovery in its effects. It enables you to return a database to its state at a time in the recent past. Flashback Database is much faster than point-in-time recovery because it does not require restoring data files from backup and requires applying fewer changes from the archived redo logs. You can use Flashback Database to reverse most unwanted changes to a database if the data files are intact. You can return a database to its state in a previous incarnation, and undo the effects of an ALTER DATABASE OPEN RESETLOGS statement. “Rewinding a Database with Flashback Database” explains how to use the FLASHBACK DATABASE command to reverse database changes. Flashback Database uses its own logging mechanism, creating flashback logs and storing them in the fast recovery area. You can only use Flashback Database if flashback logs are available. To take advantage of this feature, you must set up your database in advance to create flashback To enable Flashback Database, you configure a fast recovery area and set a flashback retention target. This retention target specifies how far back you can rewind a database with Flashback From that time onwards, at regular intervals, the database copies images of each altered block in every data file into the flashback logs. These block images can later be reused to reconstruct the data file contents for any moment at which logs were captured. When you use Flashback Database to rewind a database to a past target time, the command determines which blocks changed after the target time and restores them from the flashback logs. The database restores the version of each block that is immediately before the target time. The database then uses redo logs to reapply changes that were made after these blocks were written to the flashback logs. Redo logs on disk or tape must be available for the entire time period spanned by the flashback logs. For example, if the flashback retention target is 1 week, then you must ensure that online and archived redo logs that contain all changes for the past week are accessible. In practice, redo logs are typically needed much longer than the flashback retention target to support point-in-time

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