# Exactly-once processing in Amazon SQS
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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](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_CreateQueue.html)`, `[GetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_GetQueueAttributes.html)`, and `[SetQueueAttributes](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SetQueueAttributes.html)` 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](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessage.html)`, `[SendMessageBatch](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessageBatch.html)`, and `[ReceiveMessage](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ReceiveMessage.html)` actions in the *Amazon Simple Queue Service API Reference*.