I need to migrate millions of customers` financial transaction data from the On-Premise Mainframe system to a non-relational database in AWS. The database should also provide good performance for data retrieval and data analytics. Which of the following Database services is the most suitable?

Answer options:

A.Amazon RDS
B.Amazon RedShift
C.Amazon ElastiCache
D.Amazon DynamoDB

Answer: D
Diagrams:
On reading the scenario carefully, we notice that the Customer’s Financial transaction data is huge. It needs storage on the cloud. NoSQL databases like DynamoDB are designed to provide seamless scalability by automatically partitioning the database as it grows in size. So a NoSQL database like DynamoDB will be the most appropriate database service that can be used for the scenario.
Option A is incorrect. Here we are exclusively talking about Huge data volumes, Data retrieval and Data analytics. RDS databases are most useful for heavy transaction processing systems. They also do not exhibit automatic partitioning capabilities with increased data volume & stream processing capabilities like a NoSQL database like DynamoDB provides.
Option B is incorrect. Amazon RedShift is a Data Warehousing solution primarily used for Operational analytics on business events. Data Warehouse may comprise a big collection of an Enterprise’s structured & semi-structured data that can be used to build powerful reports & dashboards using Business Intelligence tools. Since we only have the Customer’s transactional data for our scenario, RedShift will not be a good fit here.
Option C is incorrect. We are talking about the scenario for a data migration of On-Premise Mainframe data, which will require a permanent, secure data store for storing the highly sensitive Customer’s financial data. Caching solutions are typically in-memory data stores used for supporting applications requiring sub-milliseconds response times. Caching solutions usually maintain a subset of the data present in a data store that does not change frequently. Also, caching solutions do not provide any facility for performing real-time data analytics, although they provide the best performance compared to any other data storage solutions.
Option D is CORRECT. DynamoDB provides DynamoDB Accelerator (DAX) which is a fully managed, highly available in-memory cache. This will help us speed up the performance of data retrieval that we require. DynamoDB also has a feature called DynamoDB streams that enables real-time capture of data changes using event notifications. This helps applications to perform analytics on real-time streaming data to build dashboards without impacting database performance. The stream events are asynchronous in nature to consuming applications like a Lambda function. Since the Customer’s transactional data is highly confidential & huge in volume, a robust, scalable, secure, performant data store like DynamoDB will be the best fit for our scenario.
References:
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.Partitions.html
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Streams.html