Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 520 discussion

B for me. Provisioned if we know how much traffic will come, but its unpredictable, so we have to go for on-demand

Configure DynamoDB in on-demand mode by using the DynamoDB Standard table class. This option allows DynamoDB to automatically adjust to varying traffic patterns, which is ideal for unpredictable workloads. The Standard table class is suitable for applications with moderate to high read and write throughput, and on-demand mode ensures that you are billed based on the actual usage, providing cost efficiency for variable traffic patterns.

Key word : On demand. So I think B.

On demand https://docs.aws.amazon.com/wellarchitected/latest/serverless-applications-lens/capacity.html "With on-demand capacity mode, DynamoDB charges you for the data reads and writes your application performs on your tables. You do not need to specify how much read and write throughput you expect your application to perform because DynamoDB instantly accommodates your workloads as they ramp up or down."

Not A because of "unpredictable" traffic Not C and D because we are expecting "moderate to high" traffic

Leaning towards B, it's hard to predict the capacity for A, and autoscaling doesn't respond fast

it's A. remember that : he company expects that the application read and write throughput to the database will be moderate to high provisioned throughput is cheaper than ondemand capacity right ?

Data storage: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/WorkingWithTables.tableclasses.html

On-demand mode is great for unpredictable traffic

I choose B I think the items stored in the table in this question has large size. So each read/write, a big chunk of data pass through. A capacity unit is used to describe data throughput. provision to the high capacity units will be a waste because unpredicted traffic pattern.

Unpredictable= on demand

The key factors are: With On-Demand mode, you only pay for what you use instead of over-provisioning capacity. This avoids idle capacity costs. DynamoDB Standard provides the fastest performance needed for moderate-high traffic apps vs Standard-IA which is for less frequent access. Auto scaling with provisioned capacity can also work but requires more administrative effort to tune the scaling thresholds.

Support for B from AWS: On-demand mode is a good option if any of the following are true: -You create new tables with unknown workloads. -You have unpredictable application traffic. -You prefer the ease of paying for only what you use. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html

Technically both options A and B will work. But this statement 'traffic will be unpredictable' rules out option A, because 'provisioned mode' was made for scenarios where traffic is predictable. So I will stick with B, because 'on-demand mode' is made for unpredictable traffic and instantly accommodates workloads as they ramp up or down.

https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AutoScaling.html

Not B for sure, "The company needs to scale in response to application traffic." Between A and C, I would choose C. Because it's a new application, and the traffic will be from moderate to high. So by choosing C, it's both cost-effecitve and scalable

"With provisioned capacity mode, you specify the number of reads and writes per second that you expect your application to require, and you are billed based on that. Furthermore if you can forecast your capacity requirements you can also reserve a portion of DynamoDB provisioned capacity and optimize your costs even further. With provisioned capacity you can also use auto scaling to automatically adjust your table’s capacity based on the specified utilization rate to ensure application performance, and also to potentially reduce costs. To configure auto scaling in DynamoDB, set the minimum and maximum levels of read and write capacity in addition to the target utilization percentage." https://docs.aws.amazon.com/wellarchitected/latest/serverless-applications-lens/capacity.html