[dbb01]

This is actually incorrect. The Relay/GraphQL folks explicitly call out the concept of directly exposing your persistence structure via GraphQL as detrimental. Instead, you simply describe what your business models are with GraphQL (regardless of how they're stored), just as you would with a REST api. GraphQL acts as an abstraction layer on top of your persistence. The key difference with GraphQL vs a REST API is that you don't have to commit specific endpoints that return specific models, the clients can simply pick and choose (within the confines of what your GraphQL schema allows).