Model One-to-One Relationships with Embedded Documents
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 for a full high level overview of data modeling in MongoDB.
This document describes a data model that uses embedded documents to describe relationships between connected data.
Consider the following example that maps patron and address relationships. The example illustrates the advantage of embedding over referencing if you need to view one data entity in context of the other. In this one-to-one relationship between
address data, the
address belongs to the
In the normalized data model, the
address document contains a reference to the
address data is frequently retrieved with the
name information, then with referencing, your application needs to issue multiple queries to resolve the reference. The better data model would be to embed the
address data in the
patron data, as in the following document:
With the embedded data model, your application can retrieve the complete patron information with one query.