An order-processing pipeline requires messages processed exactly once in strict sequence per order. Which SQS queue type and why?
A.Standard queue — higher throughput
Throughput is higher but ordering/exactly-once aren't guaranteed.
B.FIFO queue — strict ordering and exactly-once processing
Ordering + deduplication = FIFO. Correct.
C.Standard queue with a visibility timeout
Visibility timeout controls re-processing windows — not ordering.
D.Either — ordering is guaranteed in both
Ordering is explicitly NOT guaranteed on standard queues.
Why this answer
FIFO queues guarantee first-in-first-out ordering within a message group and exactly-once processing via deduplication — at lower throughput (~300 msg/s, ~3000 batched). Standard queues are best-effort ordering and at-least-once delivery with virtually unlimited throughput.
Correct answer: B · Last reviewed 2026-11-02
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