About Rolling Upgrades

A rolling upgrade is an alternative to a standard database upgrade that involves upgrading the databases in a Data Guard configuration. The Data Guard broker is shutdown before starting the rolling upgrade. By utilizing the capability of Data Guard to run the primary and standby databases at different releases, a designated physical standby database can first be converted to a transient logical standby database and upgraded without impacting the availability of the primary database.

A transient logical standby database is a physical standby database that can be transiently converted into a logical standby database for the duration of a rolling upgrade. After the upgrade, the logical standby database is converted back to its original role as a physical standby database.

A switchover to the upgraded standby database is then performed, followed by the upgrade of the original primary database. Applications can continue to run against the new primary database, with database downtime limited to the time taken by the switchover, which is likely to be significantly less than the downtime incurred by a conventional upgrade. Finally, a second switchover is performed back to the original primary database.