RDS Quiz
A company is hosting a MySQL database in AWS using the AWS RDS service. To offload the reads, a Read Replica has been created and reports are run off the Read Replica database. But at certain times, the reports show stale data. Why may this be the case?
A. The Read Replica has not been created properly.
B. The backup of the original database has not been set properly.
C. This is due to the replication lag.
D. The Multi-AZ feature is not enabled.
C. This is due to the replication lag.
An AWS Whitepaper on the caveat for Read Replicas is given below which must be taken into consideration by designers:
Read Replicas are separate database instances that are replicated asynchronously. As a result, they are subject to replication lag and might be missing some of the latest transactions. Application designers need to consider which queries have tolerance to slightly stale data. Those queries can be executed on a Read Replica, while the rest should run on the primary node. Read Replicas can also not accept any write queries.
For more information on AWS Cloud best practices, please visit the following URL:
https://d1.awsstatic.com/whitepapers/AWS_Cloud_Best_Practices.pdf
