From the little I can see from their blog posts, Schemaless seems to be both a sharding layer and an immutability layer that can sit on top of postgres or mysql

From the little I can see from their blog posts, Schemaless seems to be both a sharding layer and an immutability layer that can sit on top of postgres or mysql. However, discussing the costs of mutable data when you have created an immutable data storage layer doesn't make much sense.