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Difficulty: EasyImproving Database and Caching Efficiency

A financial technology company operates a web application that stores active user session tokens and transaction history metadata in a single-instance Amazon RDS for MySQL database. During peak trading hours, read-heavy traffic to the database spikes, causing CPU utilization to reach 95% and leading to transaction delays. The session tokens must be highly available, replicated across Availability Zones, and persisted to prevent users from being logged out in the event of an outage. The Solutions Architect needs to improve database efficiency and reduce query latency. Which combination of actions should the Solutions Architect take to resolve the performance issues? (Select TWO.)

  1. Deploy Amazon ElastiCache for Redis with replication enabled to store session tokens.Answer
  2. Create Amazon RDS Read Replicas to offload read queries for transaction history metadata.Answer
  3. C
    Deploy Amazon ElastiCache for Memcached to store session tokens and enable multi-AZ replication.
  4. D
    Enable Multi-AZ on the RDS instance and configure the application to route read queries to the standby DB instance.
  5. E
    Purchase an EC2 Instance Savings Plan to optimize database costs while scaling operations.

Answer

Deploy Amazon ElastiCache for Redis with replication enabled to store session tokens, and create Amazon RDS Read Replicas to offload read queries for transaction history metadata.
The correct solution involves deploying ElastiCache for Redis with replication to handle persistent, highly available session data, and implementing RDS Read Replicas to handle the read-heavy queries for transaction history, directly mitigating the CPU bottleneck on the primary database.

Step-by-Step Solution

1
Analyze database workload constraints and performance bottlenecks.
Identify that session tokens require persistence and AZ replication, while transaction metadata reads are saturating CPU capacity.
This determines which data is suitable for in-memory caching and which data requires database read replicas.
2
Select the appropriate caching engine for persistent, high-availability session states.
Select Amazon ElastiCache for Redis over Memcached.
Only ElastiCache for Redis supports the required persistence and multi-AZ replication features.
3
Implement read scaling for the relational database layer.
Deploy Amazon RDS Read Replicas and route read-heavy transaction metadata queries to them.
This offloads read operations from the primary instance, bringing down primary CPU utilization.

Key Concept

Improving database performance and efficiency involves offloading read operations via Read Replicas and shifting transient state storage to highly available in-memory caching solutions.
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Improving Database and Caching Efficiency