MongoDB Documentation, Release 3.0.4 street: "123 Fake Street", city: "Faketon", state: "MA", zip: "12345" } { patron_id: "joe", street: "1 Some Other Street", city: "Boston", state: "MA", zip: "12345" } { _id: "joe", name: "Joe Bookreader", addresses: [ { street: "123 Fake Street", city: "Faketon", state: "MA", zip: "12345" }, { street: "1 Some Other Street", city: "Boston", state: "MA", zip: "12345" } ] } Model One-to-Many Relationships with Document References Overview Pattern Data in MongoDB has a flexible schema . Collections do not enforce document structure. Decisions that affect how you model data can affect application performance and database capacity. See Data Modeling Concepts (page 145) for a full high level overview of data modeling in MongoDB. This document describes a data model that uses references (page 147) between documents to describe relationships between connected data. Consider the following example that maps publisher and book relationships. The example illustrates the advantage of referencing over embedding to avoid repetition of the publisher information. With the embedded data model, your application can retrieve the complete patron information with one query. If your application frequently retrieves the address data with the name information, then your application needs to issue multiple queries to resolve the references. A more optimal schema would be to embed the address data entities in the patron data, as in the following document: Chapter 4. Data Models 154