Another interesting approach is the way Google Cloud Datastore/Firestore works. The query engine will only allow queries that scale and can happen in a single c

Another interesting approach is the way Google Cloud Datastore/Firestore works. The query engine will only allow queries that scale and can happen in a single contiguous scan of an index range. The database can then stream results back and the work done is proportional to the size of the result set. This way you can't do queries that don't scale in production, but still don't have to increase the cognitive load on the developer. If a query is rejected by the planner that (for the most part - it's not perfect) means the query won't scale.