DBS-C01 Workload-Specific Database Design Practice Question
A company uses Amazon DynamoDB as the primary database for a global gaming application. The application requires single-digit millisecond latency for user profile lookups by user ID. However, some queries need to retrieve all active users in a region (e.g., 'us-east-1') for administrative dashboards, and these queries currently perform full table scans, causing high costs and throttling. What design approach should be taken to optimize this?
⚠ Common exam trap
Many exam-takers confuse LSIs with GSIs, assuming an LSI can be used to query by a non-key attribute like region, but LSIs are limited to the same partition key as the base table and cannot avoid a full scan when the query predicate is on a different partition key.
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 (GSI) on the region attribute.
Creating a Global Secondary Index (GSI) on the 'region' attribute allows the administrative dashboard queries to retrieve all active users in a specific region using an efficient index scan instead of a full table scan. This reduces read capacity consumption, avoids throttling, and maintains single-digit millisecond latency for the indexed queries, while the base table remains optimized for user ID lookups.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Implement DynamoDB Accelerator (DAX) to cache the dashboard queries.
Why it's wrong here
DAX caches individual item queries, not scan/query results for arbitrary attributes.
- ✗
Increase the read capacity units (RCUs) on the base table.
Why it's wrong here
Increasing capacity does not eliminate the scan; it only reduces throttling but increases cost.
- ✓
Create a global secondary index (GSI) on the region attribute.
Why this is correct
A GSI allows efficient querying on region without scanning the base table, reducing cost and throttling.
- ✗
Create a local secondary index (LSI) on the region attribute.
Why it's wrong here
LSI requires the same partition key as the base table and cannot be used to query by region alone.
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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.