SAP-C02 · Question #521
A financial services company loaded millions of historical stock trades into an Amazon DynamoDB table. The table uses on-demand capacity mode. Once each day at midnight, a few million new records…
The correct answer is D. Deploy DynamoDB Accelerator (DAX). Use provisioned capacity mode. Configure DynamoDB. To reduce DynamoDB costs for a table with a daily bulk load, bursty reads on hot keys, and currently using on-demand mode, the most effective strategy is to deploy DAX for read caching, switch to provisioned capacity mode with auto scaling to handle predictable fluctuations…
Question
A financial services company loaded millions of historical stock trades into an Amazon DynamoDB table. The table uses on-demand capacity mode. Once each day at midnight, a few million new records are loaded into the table. Application read activity against the table happens in bursts throughout the day. and a limited set of keys are repeatedly looked up. The company needs to reduce costs associated with DynamoDB. Which strategy should a solutions architect recommend to meet this requirement?
Options
- ADeploy an Amazon ElastiCache cluster in front of the DynamoDB table
- BDeploy DynamoDB Accelerator (DAX). Configure DynamoDB auto scaling. Purchase Savings
- CUse provisioned capacity mode. Purchase Savings Plans in Cost Explorer.
- DDeploy DynamoDB Accelerator (DAX). Use provisioned capacity mode. Configure DynamoDB
How the community answered
(46 responses)- A11% (5)
- B7% (3)
- C22% (10)
- D61% (28)
Why each option
To reduce DynamoDB costs for a table with a daily bulk load, bursty reads on hot keys, and currently using on-demand mode, the most effective strategy is to deploy DAX for read caching, switch to provisioned capacity mode with auto scaling to handle predictable fluctuations, and leverage Savings Plans for additional cost savings.
Deploying ElastiCache can reduce read costs but does not address the core DynamoDB capacity mode for overall cost reduction or the write capacity needed for the daily load.
This option recommends configuring DynamoDB auto scaling with on-demand capacity, which is contradictory as auto scaling is for provisioned mode, and it doesn't explicitly switch to the more cost-effective provisioned capacity.
While provisioned capacity mode and Savings Plans are good for cost reduction, this option lacks a caching layer like DAX to optimize bursty reads on hot keys, missing a key opportunity for further cost savings and performance improvements.
Deploying DynamoDB Accelerator (DAX) significantly reduces read costs and improves performance for frequently accessed hot keys, while switching to provisioned capacity mode with auto scaling can lower costs for predictable workloads and handle daily bursts; Savings Plans further reduce these costs.
Concept tested: DynamoDB Cost Optimization, DAX, Provisioned Capacity, Auto Scaling, Savings Plans
Source: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/on-demand-capacity-mode-cost-optimization.html
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