Exam AWS Certified Database - Specialty topic 1 question 144 discussion

Exam question from Amazon's AWS Certified Database - Specialty

Question #: 144
Topic #: 1

[All AWS Certified Database - Specialty Questions]

An online retail company is planning a multi-day flash sale that must support processing of up to 5,000 orders per second. The number of orders and exact schedule for the sale will vary each day. During the sale, approximately 10,000 concurrent users will look at the deals before buying items. Outside of the sale, the traffic volume is very low. The acceptable performance for read/write queries should be under 25 ms. Order items are about 2 KB in size and have a unique identifier. The company requires the most cost-effective solution that will automatically scale and is highly available.
Which solution meets these requirements?

A. Amazon DynamoDB with on-demand capacity mode
B. Amazon Aurora with one writer node and an Aurora Replica with the parallel query feature enabled
C. Amazon DynamoDB with provisioned capacity mode with 5,000 write capacity units (WCUs) and 10,000 read capacity units (RCUs)
D. Amazon Aurora with one writer node and two cross-Region Aurora Replicas

Show Suggested Answer

Suggested Answer: A 🗳️

by novak18 at April 2, 2021, 7:32 p.m.

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Jaypdv

Highly Voted 3 years, 8 months ago

I'll go for A. I think C. is a trap; if you are writing 5000 items at 2KB/second then you need 10000 WCU and 5000 RCU (assuming eventually consistent reads). C. has it in reverse.

upvoted 14 times

Most Recent 1 year, 8 months ago

Selected Answer: A

the next closest answer would be DynamoDB with Auto scaling but that it not part of the answers hence on-demand is the best answer

upvoted 1 times

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IhorK

1 year, 10 months ago

Selected Answer: A

With 2KB size for 5,000 orders per second we need 10 000 WCU (1 table write/sec = 1 WCU with blocks of 1KB). C suggest 5,000 write capacity units (WCUs), not enough.

upvoted 1 times

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awsjjj

2 years, 7 months ago

Selected Answer: A

1250 RCUs can read 10,000 KB. A is correct

upvoted 1 times

awsjjj

2 years, 7 months ago

1250 RCUs can read 10,000 KB if its eventual consistent read. A is correct

upvoted 1 times

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3 years, 7 months ago

he number of orders and exact schedule for the sale will vary each day. During the sale, approximately 10,000 concurrent users will look at the deals before buying items. Outside of the sale, the traffic volume is very low ==> Setting provisioning DynamoDB fix read 5000/write 10000 with will waste the resource when the traffic is low. It is not cost-effective. I go with A

upvoted 3 times

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