Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index is the correct choice because it delivers the single-digit millisecond writes needed for updating driver locations every few seconds, while the geohash encoding groups geographically close drivers into the same partition, enabling efficient radius queries via prefix scans on the GSI. This design directly addresses the core challenge of geospatial queries in DynamoDB: balancing write throughput with proximity search performance at scale. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of how to model location data in a NoSQL context without native geospatial indexing—a common trap is reaching for Amazon Location Service or RDS PostGIS, but DynamoDB’s geohash pattern is the optimized solution for high-frequency writes and low-latency reads. Memory tip: think “GeoHash = Grid + Hash” — the grid groups neighbors, the hash distributes writes.
DBS-C01 Workload-Specific Database Design Practice Question
This DBS-C01 practice question tests your understanding of workload-specific database design. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 designing a database for a ride-sharing application that needs to store real-time driver locations and trip history. The application requires low-latency updates to driver locations (every few seconds) and the ability to query nearby drivers within a radius. The company expects millions of drivers and trips. Which AWS database service should the database specialist recommend for storing real-time driver locations and supporting proximity queries?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index
Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index is the correct choice because it provides the low-latency writes (single-digit milliseconds) required for updating driver locations every few seconds, while the Geohash-based key enables efficient proximity queries by grouping nearby drivers into the same partition. The Global Secondary Index allows querying by geohash prefix to find drivers within a radius, scaling to millions of drivers and trips with DynamoDB's auto-scaling and fully managed infrastructure.
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.
✗
Amazon RDS for PostgreSQL with PostGIS extension
Why it's wrong here
PostGIS is powerful but may struggle with high-frequency updates and scaling to millions of drivers.
✗
Amazon ElastiCache for Redis with geospatial data types
Why it's wrong here
Redis is fast but not durable for trip history; it is typically used as a cache.
✓
Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index
Why this is correct
DynamoDB can handle high throughput and geospatial queries via Geohash.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon Timestream
Why it's wrong here
Timestream is for time-series data, not geospatial queries.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Amazon ElastiCache for Redis because of its built-in geospatial commands (GEOADD/GEORADIUS), overlooking the requirement for durable trip history storage and the scalability limits of Redis when handling millions of concurrent updates and queries.
Detailed technical explanation
How to think about this question
Geohashing works by encoding latitude/longitude into a base32 string where longer prefixes represent smaller areas; DynamoDB uses this as a partition key to colocate nearby drivers, and the GSI on a shorter geohash prefix enables radius queries by scanning only relevant partitions. Under the hood, DynamoDB's write sharding with Geohash avoids hot partitions by appending a random suffix or using a time-based component, ensuring even distribution of write traffic across partitions. In a real-world scenario with millions of drivers, this design supports sub-10ms writes and reads while maintaining cost efficiency through auto-scaling and on-demand capacity.
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: Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index — Amazon DynamoDB with a Geohash-based partition key and a Global Secondary Index is the correct choice because it provides the low-latency writes (single-digit milliseconds) required for updating driver locations every few seconds, while the Geohash-based key enables efficient proximity queries by grouping nearby drivers into the same partition. The Global Secondary Index allows querying by geohash prefix to find drivers within a radius, scaling to millions of drivers and trips with DynamoDB's auto-scaling and fully managed infrastructure.
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 designing a database for a ride-sharing application that requires real-time location updates and driver-passenger matching. The database must support geospatial queries to find nearby drivers within a radius. The expected throughput is 10,000 writes per second and 5,000 reads per second. The company wants a fully managed solution with low latency. The application team has experience with PostgreSQL. Which database design should they choose?
medium
✓ A.Use Amazon Aurora PostgreSQL with the PostGIS extension and use read replicas for scaling reads.
B.Use Amazon DynamoDB with a geospatial library to encode locations into a partition key.
C.Use Amazon DynamoDB with a global secondary index on a geohash attribute for proximity queries.
D.Use Amazon RDS for MySQL with spatial indexes and Multi-AZ deployment.
Why A: Option A is correct because Amazon Aurora PostgreSQL supports PostGIS for geospatial queries, can scale to handle the throughput with write replicas and auto-scaling, and is fully managed. Option B (DynamoDB) is not ideal for geospatial queries; it requires complex partitioning. Option C (DynamoDB with GSI) still not good for radius queries. Option D (RDS MySQL) has geospatial support but may not scale as well as Aurora.
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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.
Question Discussion
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