This is something you learn in the basic "Architecting on AWS class" (or at least they used to teach it about 4 years ago).

It's also a fairly common theme in all types of partitioned datasets, whether it's MongoDB, S3, DynamoDB, or (insert your example here--I'd love to hear it).

Good to know if you're new to S3, but not a groundbreaking article by any stretch of the imagination.