The two things, that Relational Databases typically don't do well: 1. High availablity and no downtime, ever. 2. Unlimited scalability of all operations, includ

The two things, that Relational Databases typically don't do well: 1. High availablity and no downtime, ever. 2. Unlimited scalability of all operations, including writes. Honestly, many (most?) NoSQL databases also don't really do them well. If you need these two properties, the only valid choice is really a master-less, shared-nothing database system. E.g. Apache Cassandra.