Quick Answer
The answer is to increase the DB instance class size. This directly reduces write latency on RDS MySQL by providing more CPU and memory resources, which accelerates InnoDB transaction processing and reduces internal contention during peak write loads. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of vertical scaling as a first-line performance fix—specifically, that upgrading the instance class addresses resource starvation without requiring application code changes. A common trap is to assume that switching storage types or enabling Multi-AZ alone will fix latency, but Multi-AZ primarily aids availability, not write speed. Memory tip: think “bigger engine, faster writes”—more CPU and memory mean InnoDB can commit transactions and flush logs more efficiently, directly cutting write latency.
This DEA-C01 practice question tests your understanding of data store management. 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 uses Amazon RDS for MySQL with Multi-AZ deployment. The database experiences high write latency during peak hours. The application uses InnoDB tables. Which action would reduce write latency without changing the application code?
Enable storage autoscaling on the DB instance
Why wrong: Storage autoscaling adds capacity, not performance.
Add a read replica to offload writes
Why wrong: Read replicas handle read traffic, not writes.
Enable Multi-AZ on the DB instance
Why wrong: Multi-AZ provides high availability, not performance improvement.
Increase the DB instance class size
A larger instance class provides more resources, improving write throughput.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Increase the DB instance class size
Increasing the DB instance class size (Option D) provides more CPU and memory resources, which directly improves the database's ability to handle high write loads by reducing contention and speeding up InnoDB transaction processing. This action requires no application code changes and is the most direct way to address write latency caused by resource constraints.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Enable storage autoscaling on the DB instance
Why it's wrong here
Storage autoscaling adds capacity, not performance.
Add a read replica to offload writes
Why it's wrong here
Read replicas handle read traffic, not writes.
Enable Multi-AZ on the DB instance
Why it's wrong here
Multi-AZ provides high availability, not performance improvement.
Increase the DB instance class size
Why this is correct
A larger instance class provides more resources, improving write throughput.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse read replicas with write scaling, assuming they can offload writes, when in fact they only handle SELECT queries and do not reduce write latency on the primary.
Detailed technical explanation
InnoDB write performance is heavily dependent on the buffer pool size and the ability to handle redo log writes efficiently. A larger instance class increases the buffer pool, reducing disk I/O for dirty page flushes, and provides more CPU cores for parallel query execution and transaction processing. In a Multi-AZ setup, the synchronous replication to the standby adds a small latency penalty, but scaling up the instance class mitigates this by improving overall throughput.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
The correct answer is: Increase the DB instance class size — Increasing the DB instance class size (Option D) provides more CPU and memory resources, which directly improves the database's ability to handle high write loads by reducing contention and speeding up InnoDB transaction processing. This action requires no application code changes and is the most direct way to address write latency caused by resource constraints.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This DEA-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 DEA-C01 exam.
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