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Difficulty: MediumHigh-Performing Database Solutions

An online collaborative workspace platform needs to store session state data for active users. The requirements specify that both read and write operations must consistently achieve sub-millisecond latency, even during sudden, unpredictable usage spikes. The database schema is a simple key-value structure containing user IDs and session tokens. Which database architecture should a solutions architect recommend to meet these requirements?

  1. A
    Store the session data in Amazon DynamoDB, using the current date formatted as YYYY-MM-DD as the partition key to group sessions by day.
  2. B
    Deploy an Amazon RDS for MySQL DB instance with multiple read replicas, and configure the application to write to the replicas during write spikes.
  3. Implement an Amazon ElastiCache for Redis cluster with replication enabled across multiple Availability Zones.Answer
  4. D
    Store the session data in Amazon DynamoDB configured with Provisioned Capacity Mode set to the lowest baseline to minimize database costs.

Answer

The correct architecture is to implement an Amazon ElastiCache for Redis cluster with replication enabled across multiple Availability Zones.
Implementing an Amazon ElastiCache for Redis cluster provides an in-memory data store that natively achieves sub-millisecond response times for both read and write operations. It is well-suited for key-value structures and handles unpredictable spikes through internal memory speed and scalable replication.

Step-by-Step Solution

1
Analyze database requirements.
Identify that the system requires sub-millisecond latency for both reads and writes, handles simple key-value structures, and experiences unpredictable traffic spikes.
This sets the architectural baseline, eliminating standard disk-based databases like RDS that typically average single-digit millisecond latency for writes.
2
Select the correct database technology class.
Choose an in-memory database like Amazon ElastiCache for Redis to satisfy the sub-millisecond write and read latency constraints.
In-memory caching and databases are the primary AWS services capable of delivering sub-millisecond latencies for active session stores.
3
Evaluate and eliminate incorrect scaling and partitioning strategies.
Discard strategies involving hot-key partition designs, writing to read-only RDS replicas, or under-provisioning DynamoDB capacity.
These strategies introduce throttling, database exceptions, and failures to meet performance SLAs under load.

Key Concept

In-memory database solutions, such as Amazon ElastiCache, are optimized for simple key-value operations that require sub-millisecond read/write latency under volatile workloads.
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High-Performing Database Solutions

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