You are working on an application that provides an online Car booking service using Amazon DynamoDB. This is a read-heavy application that reads car & driver location details & provides the latest position to prospective car booking customers. Which of the following can be used to have consistent data writes & avoid unpredictable spikes in DynamoDB requests during peak hours?

Answer options:

A.Write Around Cache using DynamoDB DAX.
B.Write Through Cache using DynamoDB DAX.
C.Use Side Cache using Redis along with DynamoDB.D.Write Through Cache using Redis along with DynamoDB.

Correct Answer – B
DAX is intended for applications that require high-performance reads. As a write-through cache, DAX allows you to issue writes directly so that your writes are immediately reflected in the item cache. You do not need to manage cache invalidation logic because DAX handles it for you.
For more information, please check the below link-
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/dynamodb-dg.pdf (Page 650)
Option A is incorrect. Write Around Cache is generally useful when there is a considerable amount of data to be written to the database. In this case, data is directly written to DynamoDB instead of DAX.
Option C is incorrect as Using Side Cache using Redis is eventually consistent and non-durable which may add additional delay.
Option D is incorrect. As with Write Through cache using Redis, there are chances of missing data during new scaling out.
For more information on Caching with DAX, refer to the following URL-
https://aws.amazon.com/blogs/database/amazon-dynamodb-accelerator-dax-a-read-throughwrite-through-cache-for-dynamodb/