Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 785 discussion

Standard queues provide at-least-once delivery, which means that each message is delivered at least once. FIFO queues provide exactly-once processing , which means that each message is delivered once and remains available until a consumer processes it and deletes it. Duplicates are not introduced into the queue. OPTION C

AnswerC SQS FIFO was created for such tasks Unlike standard queues, FIFO queues don't introduce duplicate messages. FIFO queues help you avoid sending duplicates to a queue. If you retry the SendMessage action within the 5-minute deduplication interval, Amazon SQS doesn't introduce any duplicates into the queue. https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/FIFO-queues-exactly-once-processing.html

C over D, because https://docs.aws.amazon.com/lambda/latest/dg/with-ddb.html Processing dynamo streams with lambda can cause duplication. SQS FIFO can be configured for High Throughput to exceed the 3000/s (batched) limit https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/high-throughput-fifo.html I previously worked with payments and would argue that either option doesn't fully solve duplications. Events might be sent multiple times from source, you definitely want to perform de-duplication and have some sort of idempotent processing for them, instead of just blindly processing each thing you're given.

c is correct

Option C: FIFO queues Exactly-Once Processing – A message is delivered once and remains available until a consumer processes and deletes it. Duplicates aren't introduced into the queue. First-In-First-Out Delivery – The order in which messages are sent and received is strictly preserved.

Option C Fifo

SQS can have duplicate messages in case of problems with the timeout window.

"The application does not process duplicate payments" is the key point, which leads us directly to SQS FIFO

Option D DynamoDB Streams helps ensure the following: Each stream record appears exactly once in the stream. For each item that is modified in a DynamoDB table, the stream records appear in the same sequence as the actual modifications to the item. DynamoDB Streams writes stream records in near-real time so that you can build applications that consume these streams and take action based on the contents.

Option c

Option B