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Difficulty: EasyCost-Optimized Database Design and Capacity Planning

A company is building a corporate internal application that runs on Amazon DynamoDB. The database experiences short, highly unpredictable spikes in query volume at random times throughout the day, followed by long periods of inactivity with no requests. The primary objective is to minimize database costs. Which capacity planning strategy is the most cost-effective for this workload?

  1. Configure the DynamoDB table with On-Demand capacity modeAnswer
  2. B
    Configure the DynamoDB table with Provisioned capacity mode and fixed capacity units
  3. C
    Configure the DynamoDB table with Provisioned capacity mode and enable Auto Scaling
  4. D
    Migrate the table to Amazon RDS with Multi-AZ enabled and use read replicas to scale the write operations during peak hours

Answer

Configure the DynamoDB table with On-Demand capacity mode
The correct option is to configure the DynamoDB table with On-Demand capacity mode. This mode charges strictly per request (read/write request units) and does not incur any baseline storage or capacity charges when the database is idle. This makes it ideal and highly cost-effective for spiky, unpredictable workloads with long periods of zero traffic.

Step-by-Step Solution

1
Analyze the workload characteristics and requirements
The database has highly unpredictable, short spikes in queries and long periods of inactivity, with a constraint to minimize cost.
Understanding workload patterns is necessary to select the correct database capacity mode.
2
Evaluate Amazon DynamoDB capacity modes against the workload profile
Provisioned capacity mode (with or without auto scaling) incurs minimum baseline costs even when the database is idle. On-Demand capacity mode charges per request and has zero idle cost.
Comparing capacity planning modes helps identify which option minimizes costs for idle periods while accommodating spikes.
3
Select the most cost-effective capacity strategy
DynamoDB On-Demand capacity mode matches the requirements perfectly as it charges only for requests served.
Determining the final configuration that satisfies the performance and cost optimization goals.

Key Concept

Selecting between DynamoDB On-Demand and Provisioned capacity modes for cost optimization of spiky, idle workloads
Estimated Time:45s
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Topics

Cost-Optimized Database Design and Capacity Planning