Exactly-once processing

Unlike standard queues, FIFO queues don't introduce duplicate messages. FIFO queues help you avoid sending duplicates to a queue. If you retry the SendMessage action within the 5-minute deduplication interval, Amazon SQS doesn't introduce any duplicates into the queue.

To configure deduplication, you must do one of the following:

• Enable content-based deduplication. This instructs Amazon SQS to use a SHA-256 hash to generate the message deduplication ID using the body of the message—but not the attributes of the message. For more information, see the documentation on the CreateQueue, GetQueueAttributes, and SetQueueAttributes actions in the Amazon Simple Queue Service API Reference.

• Explicitly provide the message deduplication ID (or view the sequence number) for the message. For more information, see the documentation on the SendMessage, SendMessageBatch, and ReceiveMessage actions in the Amazon Simple Queue Service API Reference.