DBS-C01 Workload-Specific Database Design Practice Question
A gaming company uses Amazon DynamoDB to store player profiles and game state. The access patterns include: (1) lookup by player ID, (2) query by game ID for recent games, and (3) leaderboard queries sorted by score. The current single-table design is causing hot partitions on the leaderboard queries. What design change should the company implement to resolve hot partitions?
⚠ Common exam trap
Many candidates confuse caching solutions (like DAX) with architectural fixes for hot partitions, failing to recognize that caching does not eliminate the underlying partition-level contention caused by a skewed access pattern.
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 GSI with the game ID as the partition key and a composite sort key of score and timestamp.
Creating a Global Secondary Index (GSI) with game ID as the partition key and a composite sort key of score and timestamp allows efficient leaderboard queries without hot partitions. This design distributes write activity across multiple partitions by game ID, while the composite sort key enables sorted queries by score and timestamp within each game, avoiding the hot partition issue caused by the original single-table design.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the read capacity units (RCUs) on the base table to handle the load.
Why it's wrong here
Increasing capacity does not resolve hot partition caused by uneven write distribution.
- ✗
Enable DynamoDB Accelerator (DAX) to cache frequent leaderboard queries.
Why it's wrong here
DAX caches reads, not writes; hot partitions are write-related.
- ✓
Create a GSI with the game ID as the partition key and a composite sort key of score and timestamp.
Why this is correct
GSI distributes write activity and allows efficient sorted queries per game.
- ✗
Shard the table by player ID and use application-level aggregation for leaderboards.
Why it's wrong here
Player ID sharding does not help leaderboard queries which need aggregation across players.
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Same concept, more angles
1 more way this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
hard- A.Change the sort key to a composite attribute for better filtering.
- B.Enable DynamoDB Accelerator (DAX) for the table.
- C.Increase the read capacity units for the table.
- ✓ D.Create a global secondary index with a different partition key.
Why D: 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.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.