In Data Guard, we can simply distinguish switchover and failover as planned and unplanned role transitions. A switchover is a planned role transition between the primary database and one of its standby databases. Switchover can be considered to reduce downtime during scheduled maintenance on the primary system or to test stability for future role transitions. Switchover guarantees no data loss. Using switchover, the primary database can transit to a standby role, and the standby database can transit to the primary role at any point of time. Switchover can be performed through Cloud Control, the Data Guard broker command-line interface, or by issuing SQL*Plus commands.
Once the standby database is configured and is functioning properly, you can test switchover. Switchover is used to reduce primary database downtime during any OS or hardware upgrades, which require an extended outage. A switchover allows the primary database to switch roles with its standby database...