Also, a database instance is read-only. What is the difference between the application of dual master and slave in active-passive mode? How do you usually choose?
If you want to have one that is read-only, then there is no big difference. originally, the biggest difference between the two masters and the master-slave is that both masters will synchronize to the other side in which direction, while the master-slave is unidirectional.
At present, master-slave synchronization is still commonly used, and then master-write-slave-read, read/write splitting.