The answer is to create one or more read replicas in the same region and implement Amazon ElastiCache for Redis. Read replicas directly address the need to scale PostgreSQL read performance by offloading SELECT traffic from the primary RDS instance, while ElastiCache caches frequent query results to reduce latency for repeated requests. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your understanding of read-heavy workload patterns and the distinction between scaling reads (replicas) and reducing latency (caching). A common trap is choosing Multi-AZ, which only provides high availability, not read scaling. Remember the memory tip: “Replicas for reads, Cache for speed”—replicas handle raw query volume, while ElastiCache delivers sub-millisecond responses for hot data, together forming a layered approach to improve read scalability for Amazon RDS PostgreSQL.
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 runs a PostgreSQL database on Amazon RDS for a CRM application. The database is 500 GB and experiences high read traffic. The company wants to improve read scalability and reduce latency. Which TWO actions should the company take? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Implement Amazon ElastiCache for Redis to cache common queries.
Option A is correct because Amazon ElastiCache for Redis can cache the results of frequently executed read queries, offloading read traffic from the RDS PostgreSQL instance and reducing latency for repeated queries. This is especially effective for read-heavy workloads where the same data is requested many times, as Redis provides sub-millisecond response times and reduces the load on the database.
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.
✓
Implement Amazon ElastiCache for Redis to cache common queries.
Why this is correct
Caching reduces database load.
Related concept
Read the scenario before looking for a memorised answer.
✗
Store large objects in Amazon S3 and reference them.
Why it's wrong here
Does not directly improve read scalability for transactional data.
✗
Enable Multi-AZ for automatic failover.
Why it's wrong here
Multi-AZ does not improve read scalability.
✓
Create one or more read replicas in the same region.
Why this is correct
Read replicas offload read queries.
Related concept
Read the scenario before looking for a memorised answer.
✗
Migrate data to Amazon DynamoDB with Global Tables.
Why it's wrong here
Different database, not a direct improvement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Multi-AZ (which is for high availability) with read replicas (which are for read scaling), and may incorrectly think that enabling Multi-AZ also distributes read traffic, when in fact the standby instance is not accessible for reads.
Detailed technical explanation
How to think about this question
Amazon RDS read replicas use PostgreSQL's native streaming replication to maintain an asynchronous copy of the primary database, allowing read queries to be distributed across multiple endpoints. ElastiCache for Redis can be configured with a write-through or lazy-loading caching strategy, and when combined with read replicas, it can further reduce load by caching the most frequently accessed query results, while read replicas handle the remaining read traffic. In a real-world scenario, a CRM application with dashboards and reporting queries benefits from caching aggregated results in Redis and distributing point-lookup queries across read replicas.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: Implement Amazon ElastiCache for Redis to cache common queries. — Option A is correct because Amazon ElastiCache for Redis can cache the results of frequently executed read queries, offloading read traffic from the RDS PostgreSQL instance and reducing latency for repeated queries. This is especially effective for read-heavy workloads where the same data is requested many times, as Redis provides sub-millisecond response times and reduces the load on the database.
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
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 using Amazon RDS for PostgreSQL for its transactional database. The application generates reports that query millions of rows, causing high CPU on the primary instance. The reports are not time-sensitive. What is the MOST cost-effective way to offload the reporting queries without affecting write performance?
easy
✓ A.Create an Amazon RDS Read Replica and direct reporting queries to the replica.
B.Use Amazon ElastiCache to cache report results.
C.Enable Multi-AZ to distribute reads to the standby instance.
D.Migrate reporting to Amazon Redshift.
Why A: Creating an Amazon RDS Read Replica offloads reporting queries to a separate read-only instance, preventing CPU contention on the primary. Since the reports are not time-sensitive, the replica can handle the large queries without impacting write performance, and it is cost-effective because you only pay for the replica's compute and storage.
Variation 2. A company uses Amazon RDS for Oracle for an OLTP application. The database experiences high CPU utilization during peak hours. The application is read-heavy and can tolerate eventually consistent reads. Which solution reduces CPU load on the primary database with minimal application changes?
medium
A.Implement Amazon ElastiCache to cache frequent queries
B.Upgrade to a larger instance type
✓ C.Create an RDS read replica and direct read traffic to it
D.Use DynamoDB Accelerator (DAX) as a cache layer
Why C: Option C is correct because creating an RDS Read Replica offloads read traffic from the primary Oracle instance, directly reducing CPU utilization on the primary. Since the application is read-heavy and tolerates eventually consistent reads, the replica’s asynchronous replication lag is acceptable. This solution requires minimal application changes—only modifying the connection string to route SELECT queries to the replica endpoint.
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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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