The correct answer is to use Amazon RDS Proxy to pool and share database connections. This solution directly addresses Lambda RDS connection pool exhaustion by placing a managed proxy between your Lambda functions and the RDS for PostgreSQL database, which multiplexes a small, persistent pool of connections across many concurrent Lambda invocations. Without RDS Proxy, each Lambda instance opens its own connection during peak traffic, quickly exhausting the database’s max connections and causing failures. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of serverless scaling patterns and the common trap of assuming Lambda’s built-in connection reuse is sufficient—it is not, because Lambda can scale to hundreds of concurrent executions. Remember the memory tip: “Proxy prevents pool panic”—RDS Proxy acts as a bouncer, letting only a few connections into the database while serving many Lambda guests.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. 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 migrating a monolithic application to a serverless architecture using AWS Lambda. The application reads and writes to an Amazon RDS for PostgreSQL database. The database connection pool is exhausted during peak traffic. Which design change should a solutions architect recommend to avoid connection exhaustion?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Amazon RDS Proxy to pool and share database connections.
Amazon RDS Proxy sits between the Lambda function and the RDS database, managing a pool of database connections and reusing them across multiple invocations. This prevents the Lambda function from exhausting the database connection pool during traffic spikes, as each Lambda instance does not need to open its own connection. RDS Proxy also handles connection multiplexing and reduces the overhead of establishing new connections.
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 Amazon SQS to buffer write requests to the database.
Why it's wrong here
SQS does not address connection pooling; it would add latency.
✗
Use DynamoDB Accelerator (DAX) as a caching layer.
Why it's wrong here
DAX caches DynamoDB, not RDS.
✓
Use Amazon RDS Proxy to pool and share database connections.
Why this is correct
RDS Proxy manages connection pooling, reducing connection exhaustion from Lambda.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase the max_connections parameter in the RDS parameter group.
Why it's wrong here
Increasing max_connections may hit instance limits and is not a scalable solution.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think increasing max_connections or using a queue (SQS) is sufficient, but they overlook that Lambda's concurrent execution model requires connection pooling at the database layer, which RDS Proxy uniquely provides.
Detailed technical explanation
How to think about this question
RDS Proxy uses a connection multiplexing technique where it maintains a persistent pool of connections to the database and maps multiple client connections (from Lambda invocations) to a smaller number of database connections. It also supports IAM authentication, reducing the need to store database credentials in Lambda environment variables. In real-world scenarios, Lambda functions can scale rapidly, creating hundreds of concurrent executions; without RDS Proxy, each execution would open a new database connection, quickly hitting the default max_connections limit (e.g., 80 for db.t3.micro) and causing 'FATAL: remaining connection slots are reserved for non-replication superuser connections' errors.
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.
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 Amazon RDS Proxy to pool and share database connections. — Amazon RDS Proxy sits between the Lambda function and the RDS database, managing a pool of database connections and reusing them across multiple invocations. This prevents the Lambda function from exhausting the database connection pool during traffic spikes, as each Lambda instance does not need to open its own connection. RDS Proxy also handles connection multiplexing and reduces the overhead of establishing new connections.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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