Does querying the id of a relationship field in GraphQL lead to the "join" query in the database?

[MurzNN]

I have a performance question about Payload GraphQL queries: does querying the id field of a relationship field lead to the "join" query in the database, or does it get it directly from the parent document without increasing the complexity of the database query?

Here is an example:

query($id: String!) {
  Post(id: $id) {
    title
    author {
      id
    }
  }
}

In this query, will the full "Author" document from the "Users" collection be joined on the database query, or will only the "Posts" collection be queried without any joins?

Using the Payload Local API, we can use depth: 0 to prevent additional joins in such cases, but I can't find to do the same with GraphQL queries.

So, if it leads to an additional join, is there any way to prevent this join somehow, as the id value is already available in the main document collection?