---
title: "Should You Embed or Reference Data in MongoDB Schema Design?"  
description: "Should You Embed or Reference Data in MongoDB Schema Design?"  
author: "John Smith"  
published: 2026-09-01  
updated: 2026-09-04  
canonical: https://answers.mindstick.com/qa/117131/should-you-embed-or-reference-data-in-mongodb-schema-design  
category: "MongoDB"  
tags: ["mongodb", "schema-design", "data-modeling", "NoSQL"]  
reading_time: 3 minutes  

---

# Should You Embed or Reference Data in MongoDB Schema Design?

I am designing a data model for an e-commerce platform in MongoDB. When structuring one-to-many relationships (like user addresses or order items), how do I decide whether to embed subdocuments or reference separate collections?

## Decision Matrix

Choosing between embedding and referencing depends on query patterns and document size limitations:

- **Embed when:** You have "contains" relationships, bounded one-to-few subdocuments, and the data is frequently retrieved together.
- **Reference when:** You have one-to-many or many-to-many relationships, unbounded growth, or when subdocuments are updated independently and frequently.

### Example: Embedded Schema Representation

```
{
    "_id": ObjectId("60d5ec49f1a2c3456789abcd"),
    "name": "John Doe",
    "addresses": [
        {
            "street": "123 Main St",
            "city": "New York",
            "zip": "10001"
        }
    ]
}
```

## Answers

### Answer by Lily Chitlangiya

When designing schemas in MongoDB, one of the most fundamental decisions developers face is whether to **embed** related data within a single document or **reference** it across multiple collections. Unlike traditional relational databases where normalization is standard, MongoDB gives you the flexibility to choose the approach that best fits your application's read and write patterns.

## Understanding Embedding (Denormalization)

Embedding involves storing related data in a single document as nested fields or arrays. This approach takes full advantage of MongoDB's document model and provides excellent read performance because all related data can be retrieved in a single database query.

### When to Use Embedding

- **One-to-One Relationships:** When two entities strongly belong together, such as a user and their user profile settings.
- **One-to-Few Relationships:** When an entity has a small, bounded set of related items, like a customer with a few shipping addresses.
- **Data Queried Together:** When the embedded data is almost always accessed along with the parent document.
- **Atomic Updates:** When you need atomic operations across the parent and child data without requiring multi-document transactions.

Example of an embedded schema:

```
{
    "_id": ObjectId("60d5ecb8b3f1a23456789abc"),
    "name": "Alice Smith",
    "email": "alice@example.com",
    "address": {
        "street": "123 Innovation Way",
        "city": "Tech City",
        "zipCode": "94016"
    }
}
```

## Understanding Referencing (Normalization)

Referencing involves storing relationships by saving the `ObjectId` of a document from one collection inside a document of another collection. You then use population or aggregation stages like `$lookup` to join the data when needed.

### When to Use Referencing

- **One-to-Many (Unbounded) Relationships:** When an entity can have hundreds or thousands of related items (e.g., an e-commerce product with thousands of reviews).
- **Many-to-Many Relationships:** When entities are shared across multiple parent documents, such as students enrolled in multiple courses.
- **Frequently Updated Independent Data:** When the referenced data changes frequently and is shared across documents, embedding it would cause massive write duplication.
- **Avoiding the 16MB Document Limit:** MongoDB enforces a strict 16MB maximum document size limit. Unbounded embedded arrays risk exceeding this limit over time.

Example of a referenced schema:

```
// User Document
{
    "_id": ObjectId("60d5ecb8b3f1a23456789abc"),
    "name": "Alice Smith"
}

// Order Document referencing the User
{
    "_id": ObjectId("60d5ecd1b3f1a23456789def"),
    "orderNumber": "ORD-10023",
    "totalAmount": 149.99,
    "userId": ObjectId("60d5ecb8b3f1a23456789abc")
}
```

## Summary Matrix

As a rule of thumb: **favor embedding by default** for simplicity and speed, but switch to **referencing when datasets are unbounded, heavily updated independently, or shared across multiple entities**.


---

Original Source: https://answers.mindstick.com/qa/117131/should-you-embed-or-reference-data-in-mongodb-schema-design

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