The answer is to create cross-region read replicas and route read queries to the nearest replica. This is the most cost-effective solution because the problem is high network latency between regions, not database resource contention—CPU is below 30%—so scaling the instance or migrating to Cloud Spanner would be overkill. Cross-region replicas reduce query latency by serving read traffic from a geographically closer copy of the data, minimizing round-trip time without moving the primary database. On the Google Professional Cloud Database Engineer exam, this scenario tests your ability to distinguish between performance bottlenecks caused by network distance versus local resource exhaustion; a common trap is to suggest upgrading the instance tier or switching to Spanner, which are expensive and unnecessary here. Remember the key distinction: high latency with low CPU means the bottleneck is the network, not the database. Memory tip: “Low CPU, high ping? Replica’s the thing.”
PCDE Monitor and optimize database performance Practice Question
This PCDE practice question tests your understanding of monitor and optimize database performance. 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.
You manage a Cloud SQL for PostgreSQL instance that handles OLTP workloads. Users in a different region report slow query response times. You notice that the database CPU utilization is below 30%, but network latency is high. What is the most cost-effective solution to reduce query latency without migrating the database?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create cross-region read replicas and route read queries to the nearest replica.
The correct answer is C because the issue is high network latency for users in a different region, not local resource contention. Creating cross-region read replicas allows read queries to be served from a replica closer to the users, reducing network round-trip time without migrating the database. This is the most cost-effective solution as it avoids expensive instance upgrades or a full migration to Cloud Spanner.
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.
✗
Add more memory to the instance to increase cache hit ratio.
Why it's wrong here
Adding memory may improve cache hits but does not address high network latency.
✗
Increase the instance's vCPUs to handle more concurrent connections.
Why it's wrong here
Scaling vertically does not reduce network latency between regions.
✓
Create cross-region read replicas and route read queries to the nearest replica.
Why this is correct
Read replicas reduce the network distance for read traffic, improving latency without moving the primary database.
Related concept
Read the scenario before looking for a memorised answer.
✗
Migrate the database to Cloud Spanner using a live migration service.
Why it's wrong here
Migration to Spanner is unnecessary and costly; the issue is network latency, not database scalability.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often focus on scaling the instance (CPU or memory) when the symptom is high latency, but the root cause is geographic distance, not resource exhaustion.
Detailed technical explanation
How to think about this question
Cloud SQL cross-region read replicas use asynchronous replication via PostgreSQL's streaming replication protocol, which can introduce a small replication lag (typically sub-second). For OLTP workloads, this is acceptable for read queries that tolerate eventual consistency. The replica is a full read-only copy of the primary instance, and you can use DNS-based routing or application logic to direct read traffic to the nearest replica, reducing latency from hundreds of milliseconds to single-digit milliseconds.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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.
Monitor and optimize database performance — This question tests Monitor and optimize database performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create cross-region read replicas and route read queries to the nearest replica. — The correct answer is C because the issue is high network latency for users in a different region, not local resource contention. Creating cross-region read replicas allows read queries to be served from a replica closer to the users, reducing network round-trip time without migrating the database. This is the most cost-effective solution as it avoids expensive instance upgrades or a full migration to Cloud Spanner.
What should I do if I get this PCDE 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PCDE practice question is part of Courseiva's free Google Cloud 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 PCDE exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.