LeetDezine

The SQS FIFO vs Standard decision sounds simple: need ordering? Use FIFO. Don't care? Use Standard.

That framing leads to the wrong answer more often than not. The real question isn't "do I need ordering?" — it's "what actually breaks if messages arrive out of order or more than once?"

The Core Difference

SQS Standard:

Throughput: high (can scale via sharding, region defaults are generous)

Delivery: at-least-once — the same message can appear more than once

Ordering: best-effort — messages might arrive out of order

SQS FIFO:

Throughput: 3,000 messages/sec per queue (300 per message group without batching)

Delivery: exactly-once — deduplication built in via MessageDeduplicationId

Ordering: strict — messages within a group are delivered in send order

FIFO looks better on every axis except throughput.…