A developer reports that an application using Amazon DynamoDB is experiencing high latency during peak hours. The table has a provisioned capacity of 500 read capacity units (RCUs) and 500 write capacity units (WCUs). The application uses eventually consistent reads and the table is about 50 GB. The developer notices throttled write requests in CloudWatch. Which action would most effectively reduce write throttling?
Increasing write capacity units reduces throttling for write requests.
Why this answer
The developer reports throttled write requests, which directly indicates that the provisioned write capacity (500 WCUs) is insufficient to handle the peak write traffic. Increasing the provisioned write capacity for the table is the most direct and effective action to eliminate write throttling, as it raises the limit on write operations per second. Option C is correct because it addresses the root cause—write capacity exhaustion—without introducing unnecessary components or changing read behavior.
Exam trap
The trap here is that candidates may confuse read performance solutions (DAX, consistency changes) with write throttling issues, or incorrectly assume that adding a GSI will offload write traffic, when in fact it increases the write capacity burden on the base table.
How to eliminate wrong answers
Option A is wrong because DynamoDB Accelerator (DAX) is an in-memory cache that reduces read latency, not write throttling; it does not increase write capacity or reduce write request throttling. Option B is wrong because creating a global secondary index (GSI) does not reduce write throttling on the base table; in fact, GSIs consume additional write capacity from the base table's provisioned throughput, potentially worsening throttling. Option D is wrong because switching from eventually consistent reads to strongly consistent reads doubles the read capacity consumption per read request, increasing read throttling risk and having no effect on write throttling.