Quick Answer
The answer is 65%. This is the recommended CPU utilization threshold for Cloud Spanner because sustained usage above this level introduces queuing and contention within the distributed system, causing increased latency and performance degradation before the instance reaches a critical state. On the Google Professional Cloud Database Engineer exam, this question tests your understanding of proactive monitoring versus reactive alerting—a common trap is choosing 80% or 90%, which are typical for traditional databases but dangerously high for Spanner’s shared processing model. The key insight is that Spanner’s CPU metric includes both user and system overhead, so 65% acts as an early warning buffer, giving you time to scale nodes or optimize queries. Remember the memory tip: “65 is the line—before it, performance is fine; after it, latency climbs.”
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 need to set up a Cloud Monitoring alert for a Cloud Spanner instance to notify when the CPU utilization exceeds a threshold that could indicate performance degradation. What is the recommended CPU utilization threshold for Cloud Spanner?
90%
Why wrong: 90% indicates severe capacity issues.
40%
Why wrong: 40% is too low; it would generate false alarms.
80%
Why wrong: 80% is too high; performance may already be affected.
65%
65% is the recommended threshold to maintain performance headroom.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
65%
The recommended CPU utilization threshold for Cloud Spanner is 65%. This value is based on Google's best practices, as sustained CPU usage above 65% can lead to increased latency and performance degradation due to queuing and contention. Setting the alert at 65% provides a proactive warning before the instance reaches a critical state, allowing time for scaling or optimization.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
90%
Why it's wrong here
90% indicates severe capacity issues.
40%
Why it's wrong here
40% is too low; it would generate false alarms.
80%
Why it's wrong here
80% is too high; performance may already be affected.
65%
Why this is correct
65% is the recommended threshold to maintain performance headroom.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Google Cloud often tests the misconception that higher thresholds like 80% or 90% are acceptable for alerting, but Cloud Spanner's distributed architecture requires a lower threshold to account for queuing effects and maintain consistent low latency.
Detailed technical explanation
Cloud Spanner's CPU utilization metric reflects the average CPU usage across all nodes in the instance. When CPU exceeds 65%, the probability of request queuing increases due to the non-linear relationship between utilization and latency (similar to Little's Law in queuing theory). In real-world scenarios, a sudden spike to 80% during a query-heavy workload can cause cascading delays, especially for strongly consistent reads, making the 65% threshold a critical early warning for capacity planning.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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FAQ
Monitor and optimize database performance — This question tests Monitor and optimize database performance — Read the scenario before looking for a memorised answer..
The correct answer is: 65% — The recommended CPU utilization threshold for Cloud Spanner is 65%. This value is based on Google's best practices, as sustained CPU usage above 65% can lead to increased latency and performance degradation due to queuing and contention. Setting the alert at 65% provides a proactive warning before the instance reaches a critical state, allowing time for scaling or optimization.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
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.
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