In MongoDB, both updateOne() and findOneAndUpdate() are used to modify a document in a collection, but they serve different purposes and have distinct use cases.

Use Cases for updateOne() Over findOneAndUpdate() When You Don’t Need the Updated Document

updateOne() only modifies a document and does not return the updated version. If you don’t need to retrieve the modified document, updateOne() is more efficient. Example: Incrementing a counter field in a document. Performance Considerations

Since updateOne() does not return the modified document, it is generally faster and uses fewer resources. If your operation is part of a batch update where you don’t need immediate feedback, updateOne() is preferred. Bulk Updates Without Retrieving Data

When performing multiple updates in quick succession, retrieving documents using findOneAndUpdate() could create unnecessary overhead. Example: Logging system updates where you append to a log field but never read it immediately. Atomicity and Transactions

updateOne() can be used within multi-document transactions in MongoDB, whereas findOneAndUpdate() is usually used outside of transactions. Example: Updating user account balances in a financial application. Write-Only Operations (Avoiding Read Operations for Efficiency)

If your application does not require reading the document before updating it, updateOne() avoids an extra read step. Example: Updating a user's last login timestamp. When You Don't Need Sorting

findOneAndUpdate() allows sorting before updating, which can be unnecessary overhead if you already know which document to update. Example: Updating a document by its _id (since it’s unique, sorting is unnecessary). Reduced Locking Overhead

updateOne() directly modifies the document without first fetching it, reducing potential locking contention in high-concurrency scenarios. Example: Updating stock quantities in an e-commerce application during flash sales. When to Use findOneAndUpdate() Instead? When you need the updated document after modification. When you need to return the previous document for comparison or logging. When sorting is important (e.g., updating the latest or oldest document based on a timestamp).