DVA-C02 Troubleshooting and Optimization Practice Question
A developer is troubleshooting a slow-running Amazon RDS for MySQL query. The query performance has degraded over time. Which approach should the developer take first to identify the cause?
⚠ Common exam trap
DVA-C02 often tests the 'diagnose before remediate' principle — candidates are tempted to pick scaling or caching actions, but the question asks for the FIRST step, which is always observability (Performance Insights, slow query log, EXPLAIN).
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable Performance Insights and review the database load
Amazon RDS Performance Insights is the first-line diagnostic tool for identifying why a query has degraded — it visualizes database load (DBLoad) sliced by SQL statement, wait event, user, and host, showing exactly which query and which wait state is consuming resources. Enabling it is non-invasive and provides the evidence needed before making any infrastructure change. The other options are remediation steps that should only follow diagnosis.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable Performance Insights and review the database load
Why this is correct
Enabling Amazon RDS Performance Insights is the most effective initial step for diagnosing slow database performance. It provides a visual dashboard of database load, breaking down wait events, active sessions, and top SQL queries over time. This granular visibility allows developers to pinpoint specific bottlenecks, such as I/O waits, CPU contention, or inefficient query execution plans, before implementing any corrective actions.
- ✗
Upgrade the DB instance to a larger instance class
Why it's wrong here
Upgrading the DB instance to a larger class is a vertical scaling action that increases CPU, memory, and I/O capacity. However, without first diagnosing the root cause of the slowdown, this could be a premature and costly solution. If the bottleneck is due to inefficient queries or poor indexing, simply adding more resources will not resolve the underlying problem and may only mask it temporarily.
- ✗
Create a read replica to offload read traffic
Why it's wrong here
Creating a read replica primarily serves to offload read-heavy workloads from the primary database instance, improving its performance for writes and other operations. This action does not address slow query performance on the primary instance if the issue stems from unoptimized write queries, locking, or resource contention specific to the main database. Therefore, it fails to diagnose or resolve the fundamental cause of a general slowdown.
- ✗
Enable the MySQL query cache
Why it's wrong here
Enabling the MySQL query cache is an outdated and generally counterproductive approach for modern database performance tuning. The query cache is deprecated in MySQL 5.7 and removed in MySQL 8.0 due to its significant limitations, including high contention and invalidation overhead, especially in write-heavy or highly concurrent environments. It often introduces more performance problems than it solves, making it an unsuitable solution for troubleshooting slow queries.
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Same concept, more angles
1 more way this is tested on DVA-C02
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 developer is troubleshooting a slow-running query in Amazon RDS for MySQL. The query is used by a reporting dashboard. Which AWS service should the developer use to identify the bottleneck?
easy- A.AWS X-Ray
- B.AWS CloudTrail
- ✓ C.Amazon RDS Performance Insights
- D.Amazon CloudWatch Logs
Why C: Amazon RDS Performance Insights provides a detailed analysis of database performance, including wait events and SQL query performance, helping identify bottlenecks.
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
This DVA-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 DVA-C02 exam.