Most of the configurations that we have discussed so far in this book had a one way replication stream. There are a few scenarios where such a setup will not be adequate. A very common usage where a single stream of replication will not be sufficient is a distributed environment where the database is divided into region-specific databases but the users can access the information of any region from any database. In order to keep the tables in sync in such an environment, you need multiple streams to synchronize the data both ways. Such a setup is called active-active or multimaster replication setup.

Another popular use of using active-active replication is maintaining a replicated system which could also be used to serve the complete production load in the event of a failover. Although, you can create a read-only standby database which is kept in sync with the primary database using Active Dataguard, but cannot perform any changes...