AWS Certified Developer – Associate — Question 11

A Developer must build an application that uses Amazon DynamoDB. The requirements state that the items being stored in the DynamoDB table will be 7KB in size and that reads must be strongly consistent. The maximum read rate is 3 items per second, and the maximum write rate is 10 items per second.
How should the Developer size the DynamoDB table to meet these requirements?

Answer options

• A. Read: 3 read capacity units Write: 70 write capacity units
• B. Read: 6 read capacity units Write: 70 write capacity units
• C. Read: 6 read capacity units Write: 10 write capacity units
• D. Read: 3 read capacity units Write: 10 write capacity units

Correct answer: B

Explanation

The correct answer is B because for strongly consistent reads, each read capacity unit can handle 4KB of data, so for 7KB items, you need 2 read capacity units per item, totaling 6 for 3 items per second. The write capacity units required are calculated based on the maximum write rate, which is 10 items per second, and since each item is 7KB, you need 70 write capacity units to accommodate the writes. The other options either under-assign or miscalculate the required capacity units.