Role transition is the change of role between primary and standby databases.
It can happen in the following two cases:
i. Switchover, where primary database is switched to standby database and standby database is switched to primary database
ii. Failover, where a standby database can be used as a disaster recovery solution in case of a failure in the primary database
It can happen in the following two cases:
i. Switchover, where primary database is switched to standby database and standby database is switched to primary database
ii. Failover, where a standby database can be used as a disaster recovery solution in case of a failure in the primary database