SQS FIFO Queues and Dead-Letter Queues

When message ordering matters or when messages consistently fail processing, you need more than a Standard queue. FIFO queues guarantee the order of message processing, while dead-letter queues (DLQs) capture messages that cannot be processed after repeated attempts. Together, they form the backbone of robust, fault-tolerant messaging systems.

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FIFO Queues in Depth

FIFO stands for First-In, First-Out. Messages are delivered in the exact order they were sent and are processed exactly once.

When to Use FIFO Queues

Scenario	Why FIFO?
Financial transactions	Debits and credits must be applied in order
Inventory management	Stock updates must be processed sequentially
User action sequences	Login, action, logout must happen in order
Command processing	Commands must execute in the sequence issued
Workflow steps	Each step depends on the previous one completing

Creating a FIFO Queue

FIFO queue names must end with the .fifo suffix:

my-order-queue.fifo
payment-processing.fifo

Message Group ID