CSAA – Design High-Performing Architectures – RDS ACID

[rajrenu1984]

Hello DOJO team, It’s been a week since I enrolled for the CSAA practice exams and first of all wanted to thank you guys for the excellent questions and detailed explanations for the Correct as well as Incorrect options. I need a clarification on the below question:

“You are managing a global news website which is deployed to AWS and is using MySQL RDS. The website has millions of viewers from all over the world which means that the website has read-heavy database workloads. All database transactions must be ACID compliant to ensure data integrity.”

In this scenario, which of the following is the best option to use to increase the read throughput on the MySQL database?

a. Enable Amazon RDS Read Replicas

b. Enable Multi-AZ deployments

c. Use SQS to queue up the requests

d. Enable Amazon RDS Standby Replicas

Answer provided was “Enable Amazon RDS Read Replicas”, but aren’t Read replicas ASYNCHRONOUS eventually consistent? So isn’t “Enable Multi-AZ deployments” a better answer considering they do SYNCHRONOUS replication and we get read after write consistency as part of ACID’s Consistency requirement?

I am a little confused here, would appreciate it if you can clarify or explain further on the above for me?

Thanks

Raj

[Jon-Bonso]

Hi Raj,

Thank you for posting your question. The scenario clearly said that the website has read-heavy database workloads and it needs to increase the read throughput of the database. These key phrases warrant the use of Read Replicas:

https://aws.amazon.com/rds/features/read-replicas/

It is true that a Read Replica replicates data from the master to the replica asynchronously, while Multi-AZ nodes do this synchronously. But the replication process is of no relevance in the scenario at all. The main issue here is the read performance of your application. An RDS database will still be ACID-compliant even it has Read Replicas or in an Multi-AZ deployments configuration.

Let us know if you need further assistance. The Tutorials Dojo team is dedicated to help you pass your AWS exam on your first try!

Regards,

Jon Bonso @ Tutorials Dojo

[rajrenu1984]

Thank you very much. That clears it up for me.