DBS-C01 Workload-Specific Database Design Practice Question
A financial services company uses Amazon DynamoDB to store transaction records. The table has a partition key of 'account_id' and a sort key of 'transaction_time'. Recent queries for a specific account's transactions within a time range are experiencing high latency. The table has read capacity units set to auto-scaling. Which design change would most improve query performance?
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
✓
Create a global secondary index with a different partition key.
Creating a global secondary index (GSI) with a different partition key can distribute read traffic across multiple partitions, avoiding hot partitions caused by frequent access to the same account_id. This improves query performance for time-range queries on a specific account. Option A (changing sort key) would not help if the partition itself is overloaded. Option B (DAX) caches results but does not address hot partitions, and may not help if the queries are not cacheable. Option C (increasing RCUs) may not help if the existing partition is hot due to throttling at the partition level.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Change the sort key to a composite attribute for better filtering.
Why it's wrong here
Sort key change doesn't address partition-level contention.
- ✗
Enable DynamoDB Accelerator (DAX) for the table.
Why it's wrong here
DAX caches but does not solve hot partition read distribution.
- ✗
Increase the read capacity units for the table.
Why it's wrong here
Auto-scaling already handles capacity; hot partition is the bottleneck.
- ✓
Create a global secondary index with a different partition key.
Why this is correct
GSI with a different key distributes reads across partitions.
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This DBS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DBS-C01 exam.