Oracle: Flashback Query

The Oracle Flashback Query allows users to look backwards in time and see a consistent view of the database as it was sometime in the past. This facility is only relevant if your server is configured for Automatic Undo Management. How far backwards you can see is determined by the UNDO_RETENTION parameter (in seconds) which can be configured in the init.ora file or alternatively like this:

ALTER SYSTEM SET UNDO_RETENTION = NNNN

This facility is mainly used for recovering from accidental updates and deletes as it is not practical to set the UNDO_RETENTION to an extended period. Nevertheless it is a potentially very powerful facility.

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