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What is the difference between SQS Standard queues and FIFO queues?

Beginner

Answer

Standard queues offer nearly unlimited throughput with best effort ordering, meaning messages might occasionally arrive out of order or be delivered more than once, which is acceptable for many use cases, while FIFO queues guarantee that messages are processed in the exact order they were sent and exactly once, at the cost of a lower maximum throughput, making them ideal for situations like processing financial transactions where order and exact once delivery truly matter.

aws sqs create-queue --queue-name OrderQueue.fifo --attributes FifoQueue=true,ContentBasedDeduplication=true

Real-world example A stock trading platform uses a FIFO queue to ensure that buy and sell orders for the same account are always processed in the exact sequence they were submitted, preventing incorrect trade execution order.

Common follow-ups: What is the maximum throughput difference between Standard and FIFO queues?;How does message deduplication work in FIFO queues?

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