> we could try to divide them up by relational vs. non-relational (perhaps that’s how most of us think of the distinction anyway). But these two camps of databases are slowly converging too, with JSON datatype support in MySQL and PostgreSQL, and pseudo-JOINs and transactions in MongoDB
They might be converging if you use non-relational to mean something pretty specifc (like "MongoDB and PostgreSQL JSON"). But unless we want to coin another term that means something else than the natural english meaning, it's problematic.
There are lots of databases that are not relational, but still have schema and structure in non table centric ways, like schemaful graph databases, object databases and things like Datomic and triple stores.
They might be converging if you use non-relational to mean something pretty specifc (like "MongoDB and PostgreSQL JSON"). But unless we want to coin another term that means something else than the natural english meaning, it's problematic.
There are lots of databases that are not relational, but still have schema and structure in non table centric ways, like schemaful graph databases, object databases and things like Datomic and triple stores.