How to prevent race condition in AWS DynamoDB and Lambda

Use optimistic locking:

In distributed systems like DynamoDB, item version control using optimistic locking prevents conflicting updates. By tracking item versions and using conditional writes, applications can manage concurrent modifications, ensuring data integrity across high-concurrency environments.

Optimistic locking is a strategy used to ensure that data modifications are applied correctly without conflicts. Instead of locking data when it's read (as in pessimistic locking), optimistic locking checks if data has changed before writing it back. In DynamoDB, this is achieved through a form of version control, where each item includes an identifier that increments with every update. When updating an item, the operation will only succeed if that identifier matches the one expected by your application.