Exam AWS Certified Solutions Architect - Associate SAA-C02 topic 1 question 69 discussion

D is correct

D - The visibility timeout begins when Amazon SQS returns a message. During this time, the consumer processes and deletes the message. However, if the consumer fails before deleting the message and your system doesn't call the DeleteMessage action for that message before the visibility timeout expires, the message becomes visible to other consumers and the message is received again. If a message must be received only once, your consumer should delete it within the duration of the visibility timeout. https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-visibility-timeout.html

Visibility needs to be increase. DDDDDDDDD

DDDDDDDDDDDDDDDD

Agreed with D

DDDDDDDDDD - visibility time out,

D. Use the ChangeMessageVisibility API call to increase the visibility timeout. - The problem here is multiple EC2 instances are picking up the SAME message, processing them, and writing the results into RDS - This is caused by the visibility timeout being shorter than the processing time, resulting in timeout expiring BEFORE the EC2 instances can finish processing and DELETE the message from the queue A. Use the CreateQueue API call to create a new queue. The new queue will be subjected to the same problem B. Use the AddPermission API call to add appropriate permissions. Nothing to do with permissions C. Use the ReceiveMessage API call to set an appropriate wait time. Increasing this will change consumer polling method from short to long polling, which helps to ELIMINATE EMPTY RESPONSES

Option D is the most preferred!

D is the answer - increase ChangeVisibilityTimeout

Explanation: Keyword: SQS queue writes to an Amazon RDS From this, Option D best suite & other Options ruled out [Option A - You can't intruduce one more Queue in the existing one; Option B - only Permission & Option C - Only Retrieves Messages] FIF O queues are designed to never introduce duplicate messages. However, your message producer might introduce duplicates in certain scenarios: for example, if the producer sends a message, does not receive a response, and then resends the same message. Amazon SQS APIs provide deduplication functionality that prevents your message producer from sending duplicates. Any duplicates introduced by the message producer are removed within a 5-minute deduplication interval. For standard queues, you might occasionally receive a duplicate copy of a message (at-least- once delivery). If you use a standard queue, you must design your applications to be idempotent (that is, they must not be affected adversely when processing the same message more than once).

D is correct

Key thing to note: Your application processing time is more than the visibility timeout. So, increaseing message visibility timeout can help to prevent duplicate entries in RDS.

D sure

Correct answer is D as the SQS hides the message from other consumers for the visibility timeout, if it expires and the message is not deleted, the message would be available for other consumers leading to duplicates. ChangeMessageVisibility API would provide consumers additional time to process message and delete it once processed.

D for sure. Message visibility in Queue

it's D

D right