I've only used it to aggregate backend services rather than as an SQL query builder, and this is also how it's used at Facebook. I'd have concerns about writin

I've only used it to aggregate backend services rather than as an SQL query builder, and this is also how it's used at Facebook. I'd have concerns about writing business logic in resolvers. If I was using it with a single SQL db I'd probably write a separate non-GraphQL layer for business logic and keep the resolvers thin.