It's quite easy to do this using traditional relational database technology, and various forms of replication. We've been doing it for many years, likely before

It's quite easy to do this using traditional relational database technology, and various forms of replication. We've been doing it for many years, likely before many of today's NoSQLers were even born. In the relational world, we don't really see such capabilities as anything special. They're merely one of the many basic features we've come to expect from any relational database system worth using.