Sharding and cost-effectiveness

[AKnox67]

Hello. I’ve come across two questions in set 4 in the SAP practices exams that seem to contradict each other.

The first question begins “A leading electronics company is getting ready to do a major public announcement of its latest smartphone. Their official website uses an Application Load Balancer in front of an Auto Scaling group…” with the question, “Which of the following options could be done to solve this issue in a cost-effective way? (Select TWO.)” For this question, a possible answer is “Configure the database tier to use sharding, which will distribute the incoming load to multiple RDS MySQL instances.” However, this answer is described as incorrect because “not cost-effective unlike the options mentioned above”.

The other question begins “A legal consulting firm is running a WordPress website on EC2 instances deployed across multiple Availability Zones with a Multi-AZ RDS MySQL database instance. Their website is designed to use an eventual consistency model…” and ends with “The current DB instances are already optimized for the firm’s operational budget, with considerations for cost-effectiveness and resource utilization.” The prompt is, “Which of the following options could solve this issue? (Select THREE.)” For this question, one of the correct answers is “Implement sharding to distribute the incoming load to multiple RDS MySQL instances.”

These seem like contradictory answers to me. Please help me understand.

[AudreyST]

I’m merely a fellow learner offering my 2-cent on the questions, don’t take my response as a gospel 😅. My take: both questions ask for ways to improve the DB read performance, with DB sharding listed as possible options. The difference between the 2 questions:

1st (electronics co): pick 2 most cost effective options,

2nd (legal consulting co): pick 3 (implied) cost effective options.

My understanding of DB sharding: it is highly complex, not typically the first choice solution. Complexity & Cost (logically) have a positive correlation. Thus in the 1st Q, DB sharding is out b/c it more expensive after the 2 most correct options. However, it makes the cut in the 2nd Q b/c it is among the 3 most correct options.

[JR-TutorialsDojo]

Hello AKnox67,

Thank you for your feedback.

In the first scenario, the electronics company’s website is dealing with a high request volume, and the main goal is to improve the RDS MySQL database performance. While sharding could be effective, it also introduces complexity and additional resource requirements. This might not be the most cost-effective solution compared to other options. Therefore, the answer “Configure the database tier to use sharding” is considered less cost-effective. Take note that the question specifically asks for the two most cost-effective options.

Please consider each question’s unique requirements when evaluating solutions. Also, read the explanations for each question to understand the reasoning behind the choices.

I hope this helps! Let us know if you need any further assistance.

Regards,
JR @ Tutorials Dojo

[AKnox67]

Hello JR,

I appreciate your response and advice. It’s definitely important to watch the question carefully.

For the first scenario, the reason given for not using sharding is this: “The following options are possible answers here, but they are not cost-effective unlike the options mentioned above.” So, the only reason is cost-effectiveness.

In the second scenario, the question states that the database instances are “already optimized for the firm’s operational budget, with considerations for cost-effectiveness and resource utilization”.

Now, you’ve definitely helped me understand that for the 2nd scenario, sharding is the third best option, and the question asks for 3 options. But in this case, if sharding is “not cost-effective”, then I would think it would not be appropriate for scenario 2. Although, none of the other options are appropriate either. So it may be the most appropriate of the remaining choices.

Alan