Mongo moves your schema entirely to the application, in datomic you have to define your attributes (columns) before hand (enabling some constraints, like unique

Mongo moves your schema entirely to the application, in datomic you have to define your attributes (columns) before hand (enabling some constraints, like uniqueness and value types) but its up to the app to group them however you want (no tables), they called it the universal schema, it also enforces acids semantics. So is not as bad as mongo for structured and relational data.