You plan to develop a new application using AWS Lambda Function to process messages in Amazon SQS standard & FIFO queue. Your Team lead is concerned about scaling of AWS Lambda function triggered by Amazon SQS message as event source. Which of the following is used by AWS Lambda for scaling?

Answer options:

A.AWS Lambda uses long-polling in case of standard queue & short polling in case of FIFO queue.
B.AWS Lambda uses short polling in case of standard queue & long polling in case of FIFO queue.
C.AWS Lambda uses short polling in case of standard queue & message group ID in case of FIFO queue.
D.AWS Lambda uses long polling in case of standard queue & message group ID in case of FIFO queue.

Correct Answer – D
In the case of Standard queue, AWS Lambda uses long polling to poll queues, & once messages are available it sends them to Lambda function. In the case of FIFO queues, it has a message group ID that ensures messages in the same group are delivered to AWS Lambda.
Option A is incorrect. For FIFO queues AWS Lambda uses message group ID for scaling & not short polling.
Option B is incorrect. For FIFO queues AWS Lambda uses message group ID for scaling & not long polling. Also, for standard queues, long polling is used for scalability.
Option C is incorrect. For standard queue, AWS Lambda uses long polling for scaling.
For more information on AWS Lambda with Amazon SQS, refer to the following URLs-
https://aws.amazon.com/blogs/compute/new-for-aws-lambda-sqs-fifo-as-an-event-source/
https://docs.aws.amazon.com/lambda/latest/dg/with-sqs.html