Polymorphic Data
On this page
MongoDB uses a flexible data model, which means documents in a single collection do not need to have the same structure. Polymorphic data is data in a single collection that varies in document fields or data types.
Generally, documents in a collection are similar in structure but may contain slight variations depending on the application. To group similar, non-identical documents in a single collection you can use the Polymorphic and the Inheritance schema design patterns.
These schema designs can improve performance by storing data based on query access patterns, rather than storing data strictly based on document shape.
Use Cases
Scenario | Design Pattern Application |
|---|---|
Your application tracks professional athletes across different
sports. Your queries access all athletes, but the attributes
stored for each athlete vary depending on their sport. | Use the polymorphic pattern to group athletes in a single
collection. Even though the documents have different shapes, they
can still be accessed with a single query. |
Your application tracks books in a bookstore. Books can be available in
different forms: ebook, print, or audiobook. All books share the fields of
title, author, and genre but have additional differing fields
depending on their format. | Use the inheritance pattern to group books into a single collection.
Each book format is a child entity of the parent entity of book
that provides the shared fields of title, author, and genre
across all formats. Despite the additional differing fields of the child
entities, the shared fields from the parent entity allow them to be grouped
into a single collection. |