Amazon S3 now offers conditional writes, allowing simultaneous writes to the same object without unintentional overwriting. By providing an object’s ETag in PutObject or CompleteMultipartUpload requests, clients can check if the object is unmodified before updating it. This simplifies data updates in distributed applications and shared datasets. Clients can use the if-match header to ensure the object’s ETag matches before committing the write. This feature improves efficiency in large-scale analytics and distributed machine learning workloads. The conditional-write functionality is free in all AWS Regions and can be accessed through the AWS SDK, API, or CLI. Visit the S3 User Guide for more information.
https://aws.amazon.com/about-aws/whats-new/2024/11/amazon-s3-functionality-conditional-writes/