I've seen it with postgres-compatible DBs and Cassandra-compatible DBs. Lots of databases build their frontends this way so that people can switch from postgre

I've seen it with postgres-compatible DBs and Cassandra-compatible DBs. Lots of databases build their frontends this way so that people can switch from postgres/cassandra to their product when they need a bigger DB or better performance. I've never seen anyone swap any other kind of database.