- A
Add a read replica
A read replica distributes read queries, reducing load on the primary.
- B
Increase the number of vCPUs on the instance
Why wrong: Scaling vertically increases cost and may not solely resolve read slowness.
- C
Increase the storage size
Why wrong: Larger storage does not directly improve read speed.
- D
Enable binary logging
Why wrong: Binary logging supports point-in-time recovery, not read performance.
Question 270 of 1,000
PCDOE Optimizing service performance Practice Question
This PCDOE practice question tests your understanding of optimizing service performance. 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.
An e-commerce platform uses Cloud SQL for its database. The team notices that read queries are slow. They want to improve read performance without significant cost increase. Which action should they take?
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
✓
Add a read replica
Adding a read replica is the most cost-effective way to improve read query performance in Cloud SQL. A read replica offloads SELECT queries from the primary instance, reducing contention and latency for read-heavy workloads, without requiring a more expensive primary instance. This approach scales read capacity horizontally while keeping the primary instance's compute and storage unchanged.
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 a read replica
Why this is correct
A read replica distributes read queries, reducing load on the primary.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the number of vCPUs on the instance
Why it's wrong here
Scaling vertically increases cost and may not solely resolve read slowness.
- ✗
Increase the storage size
Why it's wrong here
Larger storage does not directly improve read speed.
- ✗
Enable binary logging
Why it's wrong here
Binary logging supports point-in-time recovery, not read performance.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud exams often test the misconception that vertical scaling (more vCPUs) is the default solution for any performance issue, but the trap here is that read-heavy workloads are best addressed by horizontal scaling via read replicas, which is more cost-efficient and avoids over-provisioning the primary instance.
Detailed technical explanation
How to think about this question
Cloud SQL read replicas use asynchronous replication based on the MySQL binary log (binlog) or PostgreSQL write-ahead log (WAL). The replica applies changes from the primary with a small lag, typically under a second in the same zone. In a real-world scenario, a read replica can serve analytics dashboards or reporting queries without impacting the primary's transactional workload, and you can add multiple replicas to scale reads further, each incurring only the cost of its compute and storage.
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.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Optimizing service performance — This question tests Optimizing service performance — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a read replica — Adding a read replica is the most cost-effective way to improve read query performance in Cloud SQL. A read replica offloads SELECT queries from the primary instance, reducing contention and latency for read-heavy workloads, without requiring a more expensive primary instance. This approach scales read capacity horizontally while keeping the primary instance's compute and storage unchanged.
What should I do if I get this PCDOE 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
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Last reviewed: Jul 4, 2026
This PCDOE 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 PCDOE exam.
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