Oracle allows a standby database to be maintained in the event of the primary database
failing. The standby database can be kept at an alternative location and Oracle will ship
the redo logs to the alternative site as they are filled and apply them to the standby database.
This ensures that the standby database is almost up to date. As an extra feature, the
standby database can be opened for read-only access, which allows some queries to be
offloaded from the primary database.