AWS SQS

What it is

Amazon SQS (Simple Queue Service) is a message queue service that decouples producers and consumers in distributed systems. Messages are stored durably until processed, absorbing load spikes and guaranteeing no message is lost.

Queue types

Type	Order	Deduplication	Throughput
Standard	Best-effort	At-least-once	Unlimited
FIFO	Guaranteed	Exactly-once	3,000 msg/s (with batching)

Key concepts

• Visibility timeout: time a message is invisible after being read
• Dead-letter queue (DLQ): queue for repeatedly failing messages
• Long polling: reduces empty requests by waiting for messages
• Message groups: ordered parallelism in FIFO

Typical pattern

Producer → SQS Queue → Lambda (consumer)
                    ↓ (failures)
              Dead-letter queue → Alert

Why it matters

SQS is the most widely used queue service in AWS and the simplest way to decouple components. With standard queues for high throughput and FIFO for guaranteed ordering, it is the foundation for patterns like work queues, buffering, and asynchronous processing.

References

• SQS Documentation — Official documentation.
• SQS Best Practices — AWS, 2024. Queue best practices.
• SQS Pricing — AWS, 2024. Pricing model.