Read replicas for performance in AWS - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

How do read replicas improve database performance?

Imagine you have a busy online store. You want to make sure many customers can browse products quickly without slowing down the main database that handles orders. How do read replicas help in this situation?

A They copy the main database and handle read requests, reducing load on the main database.

B They store backups of the database for disaster recovery only.

C They replace the main database to handle all write operations.

D They encrypt data to improve security during reads.

💡 Hint

Think about separating read and write tasks to improve speed.

Read replicas create copies of the main database that handle read requests. This reduces the work the main database must do, improving overall performance.

❓ Architecture

intermediate

Choosing the right number of read replicas

You run a web app with a main database and several read replicas. What is a good reason to add more read replicas?

A To increase the number of write operations the database can handle.

B To improve read query performance by distributing read traffic.

C To reduce the storage size of the main database.

D To automatically backup data more frequently.

💡 Hint

Think about how read replicas share the work of reading data.

Adding more read replicas spreads out the read requests, so each replica handles fewer queries, improving read performance.

❓ service_behavior

advanced

Behavior of read replicas during failover

In AWS RDS, if the main database instance fails, what happens to the read replicas?

A They automatically become writable and take over as the new main database.

B They shut down to prevent data loss.

C They delete their data and resync from a backup.

D They continue to serve read requests but do not become writable automatically.

💡 Hint

Consider what read replicas are designed for and how failover is handled.

Read replicas serve read traffic and do not automatically become writable. Failover requires promotion of a replica to writable manually or via specific configurations.

❓ security

advanced

Securing data on read replicas

Which practice best protects sensitive data on AWS read replicas?

A Disable encryption on read replicas to improve performance.

B Allow open network access to read replicas for faster connections.

C Use the same encryption settings as the main database and restrict network access.

D Store sensitive data only on read replicas, not on the main database.

💡 Hint

Think about keeping data safe both at rest and during access.

Read replicas should use encryption like the main database and have strict network controls to prevent unauthorized access.

✅ Best Practice

expert

Optimizing read replica lag in AWS RDS

You notice your AWS RDS read replicas have high replication lag, causing stale data for users. Which action best reduces this lag?

A Increase the instance class size of the read replicas to improve processing power.

B Add more read replicas without changing instance sizes.

C Switch read replicas to a different AWS region to balance traffic.

D Disable automated backups on the main database to reduce load.

💡 Hint

Think about what affects how fast replicas can apply changes.

Replication lag often happens when replicas cannot process changes fast enough. Increasing their instance size gives more CPU and memory to reduce lag.