AWS Certified Cloud Practitioner (CLF-C02)Cloud Technology and ServicesMedium
A ticketing platform must process purchase order messages in the exact order they were submitted and ensure that no order is processed more than once. Which Amazon SQS queue type should the platform use?
- AFIFO queue
- BDead-letter queue
- CDelay queue
- DStandard queue
Show answer & explanationAnswer & explanation
Correct answer: A. FIFO queue
Amazon SQS FIFO (First-In-First-Out) queues preserve the exact order in which messages are sent and received and provide exactly-once processing, which is required for strict order and no duplicate processing.
Why the other options are wrong
- B. A dead-letter queue captures failed messages for troubleshooting, not order guarantees.
- C. A delay queue postpones message visibility but does not address ordering or duplication.
- D. Standard queues offer at-least-once delivery and best-effort ordering, which can allow duplicates and out-of-order messages.
SQS FIFO Queue
An SQS queue type that guarantees messages are processed exactly once, in the exact order they were sent.
- Exactly-once processing and strict ordering
- Lower throughput than Standard queues (unless using high-throughput mode)
- Queue name must end with .fifo
Memory trick: FIFO: 'First In, First Out, no do-overs.'