The answer is to use a single Amazon RDS instance shared by all microservices. This is correct because the requirement to minimize application changes means the microservices must continue using the existing relational database with complex joins, preserving all current SQL queries and join logic without needing to decompose data or implement API-based access patterns, which would demand significant rewrites. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your ability to balance architectural purity against practical migration constraints—a common trap is assuming microservices always require separate databases, but the question explicitly prioritizes minimal changes over ideal decoupling. Remember the memory tip: “When joins must stay, share the RDS all the way.”
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. 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 migrating a monolithic legacy application to a microservices architecture on AWS. The application currently uses a relational database with complex joins. The migration must minimize application changes. Which database strategy should be used for the new architecture?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a single Amazon RDS instance shared by all microservices.
Option B is correct because the requirement to minimize application changes means the microservices must continue to use the same relational database with complex joins. A single shared Amazon RDS instance preserves the existing SQL queries and join logic without requiring data decomposition or API-based data access patterns, which would necessitate significant application rewrites.
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 a separate Amazon RDS instance for each microservice.
Why it's wrong here
Requires significant code changes to handle joins across databases.
✓
Use a single Amazon RDS instance shared by all microservices.
Why this is correct
Minimizes application changes by preserving the existing relational database schema and joins.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use Amazon Aurora with RDS Proxy in front of it.
Why it's wrong here
Does not address the need for complex joins across microservices.
✗
Use Amazon DynamoDB as a shared database for all microservices.
Why it's wrong here
NoSQL does not support complex joins and would require major refactoring.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume microservices require separate databases per service (database-per-service pattern) without considering the constraint of minimizing application changes, leading them to incorrectly choose option A.
Detailed technical explanation
How to think about this question
Under the hood, a monolithic application with complex joins relies on SQL JOIN operations executed within the same database engine, which require all referenced tables to reside in the same database instance. Sharing a single RDS instance allows the microservices to continue using the same schema and ACID transactions, avoiding the need for distributed transaction protocols like XA or eventual consistency patterns. In a real-world scenario, this approach is often a temporary stepping stone during a strangler fig migration, where the shared database is later decomposed into domain-specific databases as the application evolves.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a single Amazon RDS instance shared by all microservices. — Option B is correct because the requirement to minimize application changes means the microservices must continue to use the same relational database with complex joins. A single shared Amazon RDS instance preserves the existing SQL queries and join logic without requiring data decomposition or API-based data access patterns, which would necessitate significant application rewrites.
What should I do if I get this SAP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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 migrating a legacy monolithic application to a microservices architecture on AWS. The application has a relational database with complex queries. The team wants to minimize changes to the existing codebase. Which database migration strategy should be recommended?
hard
✓ A.Use Amazon RDS for MySQL or PostgreSQL with read replicas.
B.Use Amazon Aurora Serverless to reduce management.
C.Store data in Amazon S3 and use Athena for queries.
D.Migrate to Amazon DynamoDB for scalability.
Why A: Option C is correct because using Amazon RDS (same database engine) minimizes code changes as the application can connect via standard drivers. Option A is wrong because DynamoDB requires schema redesign. Option B is wrong because Aurora Serverless may require driver changes. Option D is wrong because S3 is for files.
Last reviewed: Jun 11, 2026
Question Discussion
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This SAP-C02 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 SAP-C02 exam.
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