The answer is to use DynamoDB Streams and AWS Lambda to maintain a separate leaderboard table, along with DynamoDB Accelerator (DAX) for caching and a global secondary index (GSI) with a score attribute for efficient sorting. This combination directly addresses the need for low-latency reads in a real-time leaderboard design pattern because DAX provides an in-memory cache that serves repeated queries with microsecond latency, reducing read load on the base table and avoiding throttling, while the GSI allows you to query the top 100 players by score without scanning the entire partition. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of DynamoDB’s read optimization strategies and the trade-offs between consistency and performance—a common trap is assuming a single table with a sort key on score alone is sufficient, but that would require a costly scan across all players. Remember the mnemonic "Stream, Cache, Index" to recall the three pillars: Streams for real-time updates, DAX for caching hot data, and a GSI for sorted queries.
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is building a real-time leaderboard for a mobile game using Amazon DynamoDB. The leaderboard displays the top 100 players by score. The table has 'game_id' as partition key and 'player_id' as sort key. The score is updated frequently. Which THREE design patterns should the company implement to ensure low-latency reads for the leaderboard? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable DynamoDB Accelerator (DAX) to cache the leaderboard query.
Option B is correct because DynamoDB Accelerator (DAX) provides an in-memory cache that can serve repeated leaderboard queries with microsecond latency, reducing the read load on the base table and avoiding throttling. For a real-time leaderboard that is read frequently, DAX ensures low-latency responses without needing to query DynamoDB directly each time.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use 'ScanIndexForward: false' on the base table to get top players.
Why it's wrong here
Base table sort key is 'player_id', not 'score'.
✓
Enable DynamoDB Accelerator (DAX) to cache the leaderboard query.
Why this is correct
Caches the query results for low-latency reads.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use 'begins_with' operator on the sort key to filter by score range.
Why it's wrong here
'begins_with' is for string sort keys, not numeric.
✓
Create a global secondary index (GSI) with 'game_id' as partition key and 'score' as sort key.
Why this is correct
Allows querying top scores per game efficiently.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use DynamoDB Streams and AWS Lambda to maintain a separate leaderboard table.
Why this is correct
Offloads leaderboard computation to a separate table.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think using ScanIndexForward on the base table (Option A) is sufficient, but they overlook that the base table's sort key is player_id, not score, so it cannot sort by score without a GSI or separate table.
Detailed technical explanation
How to think about this question
A global secondary index (GSI) with game_id as partition key and score as sort key allows efficient retrieval of the top 100 players by using Query with ScanIndexForward=false and Limit=100, leveraging the index's sort order. DynamoDB Streams combined with AWS Lambda can maintain a separate leaderboard table that is pre-computed and optimized for reads, ensuring that the leaderboard query always hits a small, sorted dataset. Under the hood, DAX caches the results of the Query operation, so subsequent identical queries avoid DynamoDB read capacity consumption and reduce latency to microseconds.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Workload-Specific Database Design — This question tests Workload-Specific Database Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable DynamoDB Accelerator (DAX) to cache the leaderboard query. — Option B is correct because DynamoDB Accelerator (DAX) provides an in-memory cache that can serve repeated leaderboard queries with microsecond latency, reducing the read load on the base table and avoiding throttling. For a real-time leaderboard that is read frequently, DAX ensures low-latency responses without needing to query DynamoDB directly each time.
What should I do if I get this DBS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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 company is building a real-time leaderboard for an online game using Amazon DynamoDB. The leaderboard must update scores within seconds and support queries for top 100 players. Which TWO design patterns should be used? (Choose TWO.)
medium
A.Create a global secondary index on the score attribute for efficient range queries.
✓ B.Use DynamoDB Streams to trigger a Lambda function that updates a separate leaderboard table.
C.Store the leaderboard in Amazon ElastiCache for Redis for low-latency reads.
✓ D.Enable DynamoDB Accelerator (DAX) for faster reads of the leaderboard.
E.Set the sort key to the score attribute for natural ordering.
Why B: Option A (DynamoDB Streams + Lambda) enables real-time updates. Option D (DAX) provides low-latency read caching for the leaderboard. Option B (GSI) could help but not for real-time top-N. Option C (ElastiCache) is an alternative but not DynamoDB-native. Option E (Sort key on score) is a good design but not a separate pattern; it's part of table design.
Last reviewed: Jun 24, 2026
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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.
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