Exam AWS Certified Solutions Architect - Professional SAP-C02 topic 1 question 433 discussion

Lambda for choosing a winner (it's a short-term task) and TTL (known before the contest starts) make sense.

This is what I hate AWS keep using impractical examples or unclear assumptions on their exam, it just train a lot of people just know yelling: "lambda is cheap, lambda is efficiency".

Here cost is the only concern and not performance, option A can be ruled out because no DAX is required. Simply Dynamo DB in option D would be more than sufficient.

Option D Migrate Storage: Migrating storage from RDS DB instances (which require a significant upfront cost) to DynamoDB (a fully managed NoSQL database service with low usage-based costs) will significantly reduce the company's expenses. Lambda Functions: Rewriting code as AWS Lambda functions (serverless computing for code execution) will eliminate the need for EC2 instances, reducing costs even further. Lambda functions are also ideal for tasks that run infrequently or have short durations. DynamoDB TTL Attribute: By using DynamoDB's TTL attribute to expire each entry at the end of the contest, the company can automatically clean up unused data without requiring manual deletion.

Option D is the most cost Efficient

remove entire DynamoDB and DAX is used for reduce RCU

Should be A. With Variable lengths of time, Lambda is not the right choice.

"the contests run for variable lengths of time" does not mean that those time periods are not known. We do not need a fixed value for TTL but can use Lambda to change timestamp depending on each contest.

Option D, The option A doesn't fulfill the requirement of cost effectiveness as there is no reason to use DAX

Correct option is A here. First of all, we don't know how much time the contest will last as per requirements, so fix the TTL it's a mistake. Second point, we can delete the entire table as we didn't the file after the end of the context, so no data to retain. Finally, for web contest, we don't know how much users will be online, and providing a cache layer might be a good solution.

D - correct.

D. There is no in memory cache requirement here for DAX. So omitting A

The question is looking for “MOST cost-effectively”. I assume DAX + DynamoDB is cheaper than DynamoDB only. Cause DAX should be able to reduce the RCU cost and improve performance. This is an online contest, which means the RCU could be very high. "the contests run for variable lengths of time" means you can't set a fix TTL for the record entry. And even you can have a fix time, the record being submitted 1 min before the deadline will still be kept for the TTL and keep generating cost.

Vote for A here reason as specified by zouwelaar

You are forgetting that the contests run for variable lengths of time. So Lambda and TTL are out.

Option D

Time To Live (TTL) for DynamoDB is a cost-effective method for deleting items that are no longer relevant. TTL allows you to define a per-item expiration timestamp that indicates when an item is no longer needed. DynamoDB automatically deletes expired items within a few days of their expiration time, without consuming write throughput.