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.
A company uses Cloud SQL for their transactional database. They are experiencing slow read performance. Which THREE actions can improve read throughput? (Choose three.)
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 offloads read queries from the primary Cloud SQL instance, distributing the read workload and improving read throughput. This is a common pattern for scaling read-heavy workloads in Cloud SQL, as replicas serve read traffic asynchronously without impacting the primary instance's write performance.
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.
✗
Enable query caching
Why it's wrong here
Cloud SQL does not have built-in query caching; this option is not applicable.
✗
Use Cloud SQL Proxy for connections
Why it's wrong here
Cloud SQL Proxy provides secure access but does not improve read throughput.
✓
Add a read replica
Why this is correct
Read replicas serve read queries, reducing load on the primary.
Related concept
Read the scenario before looking for a memorised answer.
✓
Use connection pooling
Why this is correct
Connection pooling reduces the cost of establishing connections, improving throughput.
Related concept
Read the scenario before looking for a memorised answer.
✓
Increase the tier size of the primary instance
Why this is correct
Larger tier provides more CPU and memory, improving read performance.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that connection pooling or caching alone can solve read throughput issues, but the key is that read replicas directly scale read capacity, while connection pooling only reduces connection overhead and caching is often deprecated or ineffective in transactional databases.
Detailed technical explanation
How to think about this question
Cloud SQL read replicas use asynchronous replication based on the database engine's native binlog (MySQL) or WAL (PostgreSQL) streaming. The replica applies changes from the primary with a slight lag, but for read-heavy workloads, this lag is acceptable. In real-world scenarios, you can add multiple read replicas and use connection routing (e.g., via ProxySQL or application-level logic) to distribute reads, but each replica adds cost and requires careful monitoring of replication lag.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
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 offloads read queries from the primary Cloud SQL instance, distributing the read workload and improving read throughput. This is a common pattern for scaling read-heavy workloads in Cloud SQL, as replicas serve read traffic asynchronously without impacting the primary instance's write performance.
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.
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Question Discussion
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