🃏 SQS & SNS Flashcards

Test your messaging knowledge — queue types, visibility timeout, DLQs, fan-out, and FIFO ordering.

Card 1 of 10

Question

SQS Standard vs FIFO: throughput?

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Answer

Standard: unlimited TPS. FIFO: 300 messages/second (3,000 with batching via high throughput mode).

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All SQS & SNS Flashcards

1

Q: SQS Standard vs FIFO: throughput?

A: Standard: unlimited TPS. FIFO: 300 messages/second (3,000 with batching via high throughput mode).

2

Q: What is visibility timeout?

A: Time a message is hidden from other consumers after being received. Default: 30 seconds. Max: 12 hours. If processing takes longer, call ChangeMessageVisibility.

3

Q: What is a dead-letter queue?

A: A queue that receives messages that fail processing after maxReceiveCount attempts. Helps isolate poison messages for debugging.

4

Q: What is SQS long polling?

A: Consumer waits up to 20 seconds for messages to arrive instead of returning empty immediately. Reduces API calls and cost.

5

Q: What is the SNS fan-out pattern?

A: An SNS topic publishes to multiple SQS queues. Each queue gets its own copy of the message for independent parallel processing.

6

Q: What is an SNS subscription filter policy?

A: A JSON policy on a subscription that filters messages by attributes. Only matching messages are delivered to the subscriber.

7

Q: How does SQS FIFO deduplication work?

A: Uses MessageDeduplicationId or content-based deduplication (SHA-256 hash). Duplicates within a 5-minute window are rejected.

8

Q: What is SQS message delay?

A: Delay queues postpone delivery of all new messages for 0-15 minutes. Per-message delays override queue-level settings (standard queues only).

9

Q: Max SQS message size?

A: 256 KB. For larger payloads, use the SQS Extended Client Library to store the message body in S3.

10

Q: What is a MessageGroupId in SQS FIFO?

A: Tags messages belonging to the same group for FIFO ordering. Messages in different groups can be processed in parallel.

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