That's correct re: the S3 API. What we do is we "merge" multiple write requests together to minimize the cost to you and the number of requests to S3. For example, if you write a file 1,000 times in the span of a minute, we would merge that into a single PutObject request to S3. Of course, we force flush the data every few minutes (even if it's being written frequently) in order to make sure that there's an up-to-date copy in S3.