I wonder if the future stack isn't optional typing language querying optional-sql database.

Postgresql with jsonb lets you get the best of both world : schemaless when you want it, relationnal when you need it, and acid all the time.

I found it strange that they decided to map a document over relationnal schema. I would only map the "id" property of the document to a pkey, and then dump all the rest in a jsonb column, per document type.