How to Troubleshoot High CPU on RDS Instances for AWS Database Specialty
A database engineer is troubleshooting high CPU usage on an Amazon RDS for PostgreSQL instance. Amazon CloudWatch shows CPU Utilization consistently above 90% during business hours. Which combination of actions should the engineer take to identify the root cause? (Choose TWO.)
Quick Answer
The correct combination is to enable Performance Insights and review the slow query log. Performance Insights provides a visual dashboard that breaks down database load by wait events and top SQL, directly pinpointing which queries are consuming the most CPU resources, while the slow query log captures long-running statements that often drive sustained high CPU usage on RDS for PostgreSQL. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your ability to differentiate between monitoring tools: Enhanced Monitoring gives OS-level metrics, but Performance Insights is purpose-built for query-level root cause analysis of high CPU. A common trap is choosing Enhanced Monitoring alone, which shows CPU usage but not the offending queries. Remember the mnemonic “P.I. for SQL” — Performance Insights identifies the SQL culprits, and the slow query log confirms the duration.
⚠ Common exam trap
It's easy for candidates to choose Option E (pg_stat_statements) thinking it is the only way to get query-level details, but Performance Insights (Option D) provides the same data with less effort and is the recommended AWS-native approach for this scenario.
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
✓
Review the slow query log to identify long-running queries.
Reviewing the slow query log directly identifies long-running queries that can cause sustained high CPU usage on RDS for PostgreSQL. Option D is correct because Performance Insights provides a visual dashboard of database load and top SQL queries, making it easy to pinpoint which queries are consuming the most CPU resources.
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 Enhanced Monitoring and review OS process list.
Why it's wrong here
Enhanced Monitoring shows OS-level metrics like memory and disk I/O, but not query-level CPU usage.
- ✓
Review the slow query log to identify long-running queries.
Why this is correct
Slow query logs can reveal queries that consume significant CPU resources.
- ✗
Scale up the DB instance to a larger instance class.
Why it's wrong here
Scaling up addresses symptoms but does not identify the root cause; it may also increase costs unnecessarily.
- ✓
Enable Performance Insights and review the top SQL queries.
Why this is correct
Performance Insights provides query-level performance data to pinpoint high-CPU queries.
- ✗
Install pg_stat_statements extension and query it.
Why it's wrong here
Installing `pg_stat_statements` now would only begin collecting data from this point, failing to provide immediate insight into the specific queries that *caused* the current, ongoing high CPU utilisation. The engineer needs to diagnose an existing problem, not set up future monitoring. This extension is highly valuable for proactive performance monitoring and identifying resource-intensive queries over time, aggregating execution statistics for normalised statements. It would be the correct choice if the extension were already enabled, allowing for immediate querying of historical data to pinpoint the culprits.
Go deeper
Related to this question
About these practice questions
Courseiva writes every DBS-C01 question from scratch — 1,663 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on DBS-C01
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 database specialist is monitoring an Amazon RDS for MySQL instance and notices that the 'CPUUtilization' metric is consistently above 90%. Which TWO actions should the specialist take to investigate the issue? (Select TWO.)
medium- A.Disable the MySQL query cache to free up CPU.
- ✓ B.Use Performance Insights to identify the queries that are consuming the most CPU.
- C.Increase the instance class to provide more CPU resources.
- D.Enable Multi-AZ to distribute the load to a standby instance.
- ✓ E.Enable Enhanced Monitoring to get OS-level metrics for the RDS instance.
Why B: Performance Insights identifies the queries that are consuming the most CPU, helping to locate the source of high CPU utilization. Option E is correct because Enhanced Monitoring provides OS-level metrics (e.g., CPU, memory, disk I/O) that help investigate the issue. Option A is incorrect because disabling the query cache does not help investigate CPU usage; it may even increase CPU load temporarily. Option C is incorrect because increasing the instance class is a remediation step, not an investigation action. Option D is incorrect because Multi-AZ does not distribute read load to a standby instance; the standby is only for failover, not for load distribution.
Variation 2. A database specialist is troubleshooting an Amazon RDS for SQL Server instance that is experiencing high CPU utilization. The instance has multiple databases. Which TWO actions should the specialist take to identify the cause?
medium- A.Create a read replica to offload read traffic
- ✓ B.Use Performance Insights to identify top SQL queries
- C.Increase the instance size to handle the load
- D.Modify the DB instance class to a burstable type
- ✓ E.Enable Enhanced Monitoring to view OS-level metrics
Why B: Options B and E are correct because Performance Insights helps identify top SQL queries causing high CPU, and Enhanced Monitoring provides OS-level metrics (like CPU utilization per database process) to pinpoint the source. Option A is wrong: read replicas offload read traffic but do not diagnose CPU issues. Option C is wrong: increasing instance size is a remediation, not a diagnostic step. Option D is wrong: changing to a burstable instance class is also a remediation, not diagnostic.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.