Question

If your DynamoDB items are 5 KB and you want to read 80 items per second from your table, then you need to provision ___ read capacity units for strong consistency. 1) 40 2) 80 3) 120 4) 160

Answer 1

To read 80 items per second with each item being 5 KB from a DynamoDB table with strong consistency, you need to provision 160 read capacity units. Each 5 KB item rounds up to 8 KB, requiring 2 RCUs, and thus 80 items would require 80 * 2 = 160 RCUs. So, the best answer is 4, 160.

Step-by-step explanation:

If you want to read 80 items per second from your DynamoDB table and each item is 5 KB, you need to calculate the number of read capacity units (RCUs) required for strong consistency reads.

DynamoDB's read capacity is measured in read capacity units, where 1 RCU represents one strongly consistent read per second for an item up to 4 KB in size.

Since your items are 5 KB, each read will consume more than 1 RCU.

For items larger than 4 KB, you must round up the item size to the nearest 4 KB multiple and then calculate the required capacity. In your case:

Each 5 KB item requires 2 RCUs because 5 KB rounds up to the next 4 KB increment, which is 8 KB.

Therefore, reading 80 items per second would require 160 RCUs (80 items * 2 RCUs per item).

So, to read 80 items per second with strong consistency, you need to provision 160 read capacity units.

So, the best answer is 4, 160.