Amazon SQS FIFO (First-In-First-Out) queues ensure that messages are received in the exact order they were sent. This is different from standard SQS queues, which provide best-effort ordering and may deliver messages out of sequence.

FIFO queues are designed for applications where message ordering is crucial and duplicate messages must be prevented.

1. Key Features of SQS FIFO Queues

✅ Message Ordering Guarantee

• Messages are processed in the exact order they are sent.
• Example: If a producer sends messages 1 → 2 → 3 → 4, the consumer will receive them 1 → 2 → 3 → 4.

✅ Exactly-Once Processing

• Eliminates duplicate messages using deduplication mechanisms.
• Ensures that each message is processed only once.

✅ Lower Throughput Limits Compared to Standard Queues

• 300 messages per second (without batching).
• 3,000 messages per second (with batching).
• Standard queues have unlimited throughput, but no strict ordering.

✅ Message Deduplication

• Duplicate messages within a 5-minute window can be removed.
• Deduplication is based on a deduplication ID or content-based deduplication.

✅ Message Grouping (Message Group ID)

• FIFO queues support multiple ordered message streams within a single queue using Message Group IDs.
• Messages with the same Message Group ID are processed in order, but different groups can be processed in parallel.