(Not OP) The example `{ users { posts { comments } } }` reflects that in the abstract modeling of a message board, this relationship exists. The representation

(Not OP) The example `{ users { posts { comments } } }` reflects that in the abstract modeling of a message board, this relationship exists. The representation of this relationship will change depending on the database implementation; a document db may store the data explicitly in the hierarchical form, while a relational db would store them with a series of joins.