has two modes of message acknowledgement: and . When using , messages are automatically acknowledged as soon as they’re consumed. If the consumer fails to actually consume the message, it be re-queued. If is used, the client acknowledge the message consumed, otherwise it will be re-queued automatically once the worker is disconnected. This means that a worker that does not acknowledge a message but remains connected for an extended period of time will prevent the message from being re-requeued.
The (in bytes) an SQS message can contain for this queue, set in the .
When your monthly publishing and consuming traffic exceeds 100s of millions of requests per month, the instance-hour charges for running a cluster could be less expensive than paying the per-message price. But again, the benefits of ‘ high availability and no-upkeep should be considered.While I mentioned that at the end of the Availability section and a bit in the second paragraph, it probably deserves its own section.