Question

Difficulty: EasyHigh-Performing Database Solutions

A company runs a web application that stores user account transaction data in an Amazon RDS for PostgreSQL database and session data in an Amazon DynamoDB table. Users are experiencing slow page load times. A review reveals that the RDS database is overwhelmed with read-only reporting queries, and the DynamoDB table is facing write throttling due to uneven partition distribution. Which two database configurations should a solutions architect implement to resolve these performance issues? (Select TWO.)

  1. Create Amazon RDS read replicas to handle the read-only reporting queries.Answer
  2. Use a high-cardinality, randomized attribute as the Amazon DynamoDB partition key to distribute write traffic.Answer
  3. C
    Use a monotonically increasing timestamp as the Amazon DynamoDB partition key to store session data in chronological order.
  4. D
    Configure an Amazon RDS read replica to serve as the primary automatic failover target instead of deploying Multi-AZ.

Answer

To resolve the performance issues, the solutions architect should create RDS read replicas to handle the read-only reporting queries, and use a high-cardinality, randomized attribute as the DynamoDB partition key to distribute write traffic.
Creating RDS read replicas allows the reporting queries to be directed away from the primary database, lowering CPU utilization on the writer instance. Implementing a high-cardinality partition key for DynamoDB ensures that write requests are spread evenly across multiple physical partitions, which eliminates write throttling.

Step-by-Step Solution

1
Analyze the database performance bottleneck for the Amazon RDS for PostgreSQL database.
The primary database instance is overloaded by read-only reporting queries.
To resolve read-heavy workload issues, read-only queries should be offloaded to dedicated read replicas.
2
Analyze the write throttling issue on the Amazon DynamoDB table.
The write traffic is unevenly distributed, causing a partition bottleneck.
To prevent write throttling, a high-cardinality key should be used instead of a monotonically increasing value to distribute writes evenly across partitions.

Key Concept

Scaling read workloads using RDS read replicas and designing DynamoDB partition keys to avoid partition throttling.
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