AWS SQS – Standard vs FIFO Queue
- Standard queues provide best-effort ordering which ensures that messages are generally delivered in the same order as they are sent. Occasionally (because of the highly-distributed architecture that allows high throughput), more than one copy of a message might be delivered out of order
- FIFO queues offer first-in-first-out delivery and exactly-once processing: the order in which messages are sent and received is strictly preserved
- Standard queues guarantee that a message is delivered at least once and duplicates can be introduced into the queue
- FIFO queues ensure a message is delivered exactly once and remains available until a consumer processes and deletes it; duplicates are not introduced into the queue
Transactions Per Second (TPS)
- Standard queues allow nearly-unlimited number of transactions per second
- FIFO queues are limited to 300 transactions per second per API action
- Standard queues are available in all the regions
- FIFO queues are currently available in limited regions including the US West (Oregon), US East (Ohio), US East (N. Virginia), and EU (Ireland)
SQS Buffered Asynchronous Client
- FIFO queues aren’t currently compatible with the SQS Buffered Asynchronous Client, where messages are buffered at client side and send as a single request to the SQS queue to reduce cost.
AWS Services Supported
- Standard Queues are supported by all AWS services
- FIFO Queues are currently not supported by all AWS services like
- CloudWatch Events
- S3 Event Notifications
- SNS Topic Subscriptions
- Auto Scaling Lifecycle Hooks
- AWS IoT Rule Actions
- AWS Lambda Dead Letter Queues
- Standard queues can be used in any scenarios, as long as the application can process messages that arrive more than once and out of order
- Decouple live user requests from intensive background work: Let users upload media while resizing or encoding it.
- Allocate tasks to multiple worker nodes: Process a high number of credit card validation requests.
- Batch messages for future processing: Schedule multiple entries to be added to a database.
- FIFO queues are designed to enhance messaging between applications when the order of operations and events is critical, or where duplicates can’t be tolerated
- Ensure that user-entered commands are executed in the right order.
- Display the correct product price by sending price modifications in the right order.
- Prevent a student from enrolling in a course before registering for an account.
AWS Certification Exam Practice Questions
- Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
- AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
- AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
- Open to further feedback, discussion and correction.