DBS-C01 Management and Operations Practice Question
An application is experiencing increased latency when writing to an Amazon DynamoDB table. The table uses on-demand capacity mode. The CloudWatch metric 'WriteThrottleEvents' is zero. What is the most likely cause of the increased latency?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A hot partition is causing excessive write traffic to a single partition.
On-demand DynamoDB tables can experience throttling if you exceed the previous peak traffic by more than double in a short time, but since WriteThrottleEvents is zero, the latency is likely due to a hot partition causing uneven traffic distribution. Option A is incorrect because on-demand capacity does not use WCUs; throughput is automatically scaled. Option B is incorrect because DynamoDB Accelerator (DAX) is a read cache and does not affect write latency. Option D is incorrect because on-demand tables do not have provisioned capacity; throttling would be indicated by WriteThrottleEvents, which is zero.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The write capacity units (WCUs) are set too low.
Why it's wrong here
On-demand tables automatically scale; there is no setting for WCUs.
- ✗
DynamoDB Accelerator (DAX) is not configured for writes.
Why it's wrong here
DAX is a read cache; it does not affect write latency.
- ✓
A hot partition is causing excessive write traffic to a single partition.
Why this is correct
Hot partitions can cause increased latency even when overall throughput is within limits, as a single partition's capacity is constrained.
- ✗
The table is experiencing write throttling due to exceeding the provisioned write capacity.
Why it's wrong here
On-demand tables do not have provisioned capacity; WriteThrottleEvents would be non-zero if throttling occurred.
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