[intellisense]

Yes the client queries for only data it needs and server returns only data which client requested.

With this query, { currentUser { id name todoLists { title items { name } } } }

It is up to the server how it is implemented.

- The server can fetch all the data for the user, todolist and items from the database in one go and resolve the client query mentioned above. In this case there will be overfetching from the database if the client only requested user information.

The server can also fetch the data in 3 queries

1> First to fetch the user, lets say with id 1. 2> Then get all the todos for the for user id 1. 3> Then get all the items for all the todos in step 2. Batching/Dataloaders.

All these queries can be executed in parallel on the server side. Does this make the server complex? Yes but there is also benefit to this when the user only request currentUser it does not fetch any todolists or items from the database.