Exam AWS Certified Database - Specialty topic 1 question 76 discussion

C is the correct. D is not correct because in Dynamodb when you scale up the capacity your data partition will increase accorssing to your RCU and WCU, but when you scale down the partition remain unchnaged, so the per table RCU and WCU will give poor performance. I think Auto Scaling is the correct way is such situation.

I'm going with D because we know about the increased traffic in advance because it will be due to a sale. Burst capacity is fine for unknown spikes up to 5 minutes. This even is for 3 days. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/bp-partition-key-design.html#bp-partition-key-throughput-bursting "DynamoDB provides some flexibility in your per-partition throughput provisioning by providing burst capacity. Whenever you're not fully using a partition's throughput, DynamoDB reserves a portion of that unused capacity for later bursts of throughput to handle usage spikes. DynamoDB currently retains up to 5 minutes (300 seconds) of unused read and write capacity. During an occasional burst of read or write activity, these extra capacity units can be consumed quickly—even faster than the per-second provisioned throughput capacity that you've defined for your table. DynamoDB can also consume burst capacity for background maintenance and other tasks without prior notice. Note that these burst capacity details might change in the future."

The answer is D, as we know about the event beforehand Furthermore, C will have an issue getting 10x performance quickly enough because of the cooldown.

D. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html#HowItWorks.ProvisionedThroughput.Manual

scheduled auto-scaling

D is correct, because prewarm: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.ReadWriteCapacityMode.html#HowItWorks.OnDemand

Scheduled scaling, as one way of Application Auto Scaling, is available for DynamoDB tables and global secondary indexes. It allows to "scale a resource one time only or on a recurring schedule". I understand that this is what we need for the one-time event, and it's even automated (option D is not automated). https://docs.aws.amazon.com/autoscaling/application/userguide/application-auto-scaling-scheduled-scaling.html

D In summary, Autoscaling requires consecutive data points where the target utilization value is being breached to scale up a DynamoDB table. For this reason Autoscaling is not recommended as a solution for dealing with spiked workloads.

Amazon DynamoDB auto scaling uses the AWS Application Auto Scaling service to dynamically adjust provisioned throughput capacity on your behalf, in response to actual traffic patterns. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/AutoScaling.html

Have everyone forgot cooldown during AWS Application Auto Scaling policy? We know we need to increase by 10x for AWS Application Auto Scaling policy with cooldowns it will take time to get there.

A. This is achieved by D, but D is more precise. B. Does DynamoDB support burst capacity? C.The question is not about the application, but about DynamoDB D. Using provisioned capacity to meet the expected demand is one way of doing it. Using provisioned capacity with auto-scaling would also work. And of course on-demand would be an option.

C- I will go with autoscaling. Why change 2 times config, when autoscaling is designed for that..

D is wrong because on-demand to maximum 2 times of previous peak, it can not scale to 10x. https://aws.amazon.com/premiumsupport/knowledge-center/on-demand-table-throttling-dynamodb/

C is correct. AWS always recomend to use auto scaling when you can predict usage. I now that I excpect 10x more traffic.

I"m going with D because auto scaling on the application doesn't mean the DB can accommodate the increased RW on the DB. Since the peak traffic is predictable then it may be best to pre-provision ahead and reduce after sale is over. I may be wrong though

I go with D. although If the answer D also includes autoscaling it would have been easy to choose D

C. Set an AWS Application Auto Scaling policy for the table to handle the increase in traffic