The answer is to use pg_terminate_backend to terminate the long-running queries. This is the correct first step to reduce high CPU on RDS PostgreSQL because the immediate symptom—high CPU utilization—is being caused by active queries consuming processing cycles for minutes on end. By killing those processes with pg_terminate_backend, you free up CPU resources instantly, directly addressing the root cause shown in the pg_stat_activity output before considering configuration changes or scaling. On the AWS Certified Database Specialty DBS-C01 exam, this scenario tests your ability to prioritize reactive troubleshooting over proactive optimization; a common trap is jumping to modify work_mem or scale the instance, which wastes time when the real fix is terminating the offending sessions. Remember the memory tip: "Kill the query, not the instance"—always terminate long-running active queries first when CPU spikes, as they are the most likely culprit.
DBS-C01 Management and Operations Practice Question
This DBS-C01 practice question tests your understanding of management and operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 database administrator is troubleshooting an Amazon RDS for PostgreSQL DB instance that is experiencing high CPU utilization. The administrator runs the following query to find the current running queries:
SELECT pid, now() - pg_stat_activity.query_start AS duration, query, state
FROM pg_stat_activity
WHERE state = 'active';
The output shows a high number of queries with a state of 'active' and durations exceeding several minutes. What should the administrator do FIRST to reduce CPU utilization?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use pg_terminate_backend to terminate the long-running queries.
Option C is correct because the immediate cause of high CPU utilization is the long-running active queries consuming resources. Using pg_terminate_backend to terminate these queries will quickly free up CPU cycles, providing immediate relief. This is the first troubleshooting step before making configuration changes or scaling, as it directly addresses the symptom shown in the pg_stat_activity output.
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.
✗
Modify the max_connections parameter to limit concurrent sessions.
Why it's wrong here
This won't affect already connected sessions.
✗
Scale up the DB instance to a larger instance class.
Why it's wrong here
This is a reactive measure and not the first step.
✓
Use pg_terminate_backend to terminate the long-running queries.
Why this is correct
Terminating long-running queries immediately reduces CPU usage.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable pg_stat_statements to collect query performance data.
Why it's wrong here
This adds overhead and does not solve the immediate problem.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may choose to scale up or adjust parameters first, overlooking that the immediate problem is the active long-running queries, which can be resolved quickly with pg_terminate_backend without incurring cost or configuration changes.
Detailed technical explanation
How to think about this question
pg_terminate_backend sends a SIGTERM to the backend process, which allows the query to clean up its resources before exiting, unlike pg_cancel_backend which only cancels the current query. In PostgreSQL, long-running queries can hold locks and consume shared buffers, so terminating them may also release contention for other sessions. In a real-world scenario, a single runaway query from a reporting tool can spike CPU to 100% and degrade all other workloads, making targeted termination the fastest recovery action.
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
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
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.
Management and Operations — This question tests Management and Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use pg_terminate_backend to terminate the long-running queries. — Option C is correct because the immediate cause of high CPU utilization is the long-running active queries consuming resources. Using pg_terminate_backend to terminate these queries will quickly free up CPU cycles, providing immediate relief. This is the first troubleshooting step before making configuration changes or scaling, as it directly addresses the symptom shown in the pg_stat_activity output.
What should I do if I get this DBS-C01 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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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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