ORA-16623: database detected role change
Cause: A successful switchover or failover operation had been completed and was detected during database startup or broker health check. If this database was unavailable during a switchover or failover operation, it may not be a viable standby database for the new primary database and was disabled by the Data Guard broker.
Action: Connect to the new primary database and examine the broker configuration for databases that were disabled and that may require reinstatement or re-creation.
错误码：ORA-16623: database detected role change
详细说明：当事务处理器数据库检测到有节点中每个数据库状态改变时，错误ORA-16623就会被触发。
1. 首先，应尝试使用 racgmons 来进行诊断，确定问题出现的原因。
2. 运行检查程序来检查数据库的健康状况。
3. 检查 ASM 实例并确定状态是否正常，如果有问题，应该根据实例的日志来查看问题的原因。
4. 根据事务处理器日志确定问题的根源，确定要采取什么措施来解决问题。
5. 执行合适的重新加载和恢复操作，如果可能，就尝试重新启动节点上的数据库。
6. 尝试使用ASM实例重新挂载确定是否节点状态已经正常解决了数据库问题。
7. 如果数据库问题依然出现，请考虑打补丁，升级服务器等操作。