The answer is to add a Memorystore for Redis cache, create read replicas, and optimize queries with indexing. These three actions directly lower read latency by offloading repeated reads from the primary database instance—Redis serves frequently accessed data from memory, read replicas distribute read traffic across copies, and better indexes reduce the work PostgreSQL must do per query. On the Google Professional Cloud Database Engineer exam, this question tests your ability to distinguish cost-effective architectural changes from brute-force scaling; the common trap is choosing vertical scaling, which adds cost without addressing the root cause of read contention. Remember the mnemonic “CRO”—Cache, Replicas, Optimization—to recall that reducing read latency requires caching hot data, distributing reads, and sharpening queries, not just adding more CPU or RAM.
PCDE Monitor and optimize database performance Practice Question
This PCDE practice question tests your understanding of monitor and optimize database 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.
You manage a Cloud SQL for PostgreSQL instance that is experiencing high read latency. You have already tuned the buffer cache and queries. Which THREE actions can further reduce read latency? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the number of vCPUs on the primary instance.
Creating read replicas offloads reads; adding an in-memory cache (e.g., Redis) reduces database load; and query optimization (indexing, rewriting) directly reduces read time. Vertical scaling adds hardware but may not be cost-effective; enabling query logging adds overhead, not help.
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 the PostgreSQL slow query log and analyze it.
Why it's wrong here
Logging is for diagnostics, not a direct latency reduction action.
✗
Use connection pooling to reduce the number of open connections.
Why it's wrong here
Connection pooling manages connections but does not directly reduce read latency.
✓
Increase the number of vCPUs on the primary instance.
Why this is correct
More vCPUs can process more queries concurrently, reducing queue time.
Related concept
Read the scenario before looking for a memorised answer.
✓
Create read replicas in the same region to distribute read traffic.
Why this is correct
Read replicas handle read queries, reducing load on the primary.
Related concept
Read the scenario before looking for a memorised answer.
✓
Add a Memorystore for Redis cache in front of the database for frequently accessed data.
Why this is correct
Caching reduces reads to the database, lowering latency.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 PCDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Increase the number of vCPUs on the primary instance. — Creating read replicas offloads reads; adding an in-memory cache (e.g., Redis) reduces database load; and query optimization (indexing, rewriting) directly reduces read time. Vertical scaling adds hardware but may not be cost-effective; enabling query logging adds overhead, not help.
What should I do if I get this PCDE question wrong?
Identify which PCDE exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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