Schema Design Anti-Patterns

Schema design anti-patterns are inefficient ways to structure your database schema. They can create unnecessary complexity and cause performance issues. Recognizing and avoiding schema design anti-patterns can help create applications with better performance.

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To learn more about schema design anti-patterns, see the following pages:

Schema Design Anti-Pattern	Definition
Avoid Unbounded Arrays	A document stores an unbounded array that can grow to be too large. The large array can exceed the document size limit and cause a decrease in index performance.
Reduce Number of Collections	You create a large number of collections in your database. Having too many collections can decrease storage engine performance.
Remove Unnecessary Indexes	Your collection contains unnecessary indexes. Unnecessary indexes consume additional disk space and can degrade write performance.
Reduce Bloated Documents	Your collection has excessively large documents. The large documents can degrade the performance of your most common queries.
Reduce $lookup Operations	You are running too many $lookup operations on your data. This increases query complexity and reduces query performance.

Details

The MongoDB Atlas Performance Advisor (available for M10 clusters or higher) and MongoDB Compass Performance Insights identify schema design anti-patterns in your database. It is important to understand the Atlas anti-pattern warnings in order to properly correct the issues and prevent the use of anti-patterns.

View Schema Suggestions in Performance Advisor

In Atlas, go to the Clusters page for your project.

WARNING: Navigation Improvements In Progress We're currently rolling out a new and improved navigation experience. If the following steps don't match your view in the Atlas UI, see the preview documentation.

If it's not already displayed, select the organization that contains your desired project from the Organizations menu in the navigation bar.
If it's not already displayed, select your desired project from the Projects menu in the navigation bar.
If it's not already displayed, click Clusters in the sidebar.
The Clusters page displays.

Click the replica set where the collection resides.

If the replica set is part of a sharded cluster, first click the sharded cluster containing the replica set.

Click Performance Advisor.

View recommendations.

In the Performance Advisor tab, click Explore Recommendations on the Improve Schema card.

(Optional) Change which host results to view.

By default, the results correspond to one of the primary hosts. However, you can select another host from the drop-down.

Learn More

For recommended schema design patterns, see the following: Schema Design Patterns and Apply Design Patterns.

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Archive Data

Avoid Unbounded Arrays