- A
Monitor 'cloudsql.googleapis.com/network/received_bytes_count' and compare with connection count.
Why wrong: Network bytes received is a throughput metric, not a direct indicator of connection spikes.
- B
Monitor 'cloudsql.googleapis.com/database/mysql/replication/seconds_behind_master' and compare with query latency.
Why wrong: This metric tracks replication lag, which is unrelated to connection spikes causing performance issues.
- C
Monitor 'cloudsql.googleapis.com/instance/uptime' and check for instance restarts during degradation.
Why wrong: Uptime indicates availability, not connection spikes or performance.
- D
Monitor 'cloudsql.googleapis.com/database/mysql/threads/threads_connected' and correlate with CPU utilization and query latency.
Threads connected directly indicates active connections, and correlating with CPU and latency helps identify the impact.
Quick Answer
The answer is to monitor the `cloudsql.googleapis.com/database/mysql/threads/threads_connected` metric and correlate it with CPU utilization and query latency. This is correct because `threads_connected` directly measures active connections to the MySQL instance, and a sudden spike in this metric often triggers resource contention, which manifests as elevated CPU usage and slower query response times. On the Google Professional Cloud Database Engineer exam, this scenario tests your ability to distinguish between connection-level metrics and performance indicators—a common trap is to focus solely on connection count without linking it to resource pressure. Remember that a connection spike alone isn't the problem; it’s the resulting CPU and latency degradation that confirms the correlation. Memory tip: think "Threads + CPU + Latency = The Troubleshooting Trinity" for connection spike analysis.
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.
Your Cloud SQL for MySQL instance is experiencing intermittent performance degradation. You suspect that the issue is due to a sudden spike in connections from a specific application. Which metric and monitoring approach would best help you correlate the connection spike with performance degradation?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Monitor 'cloudsql.googleapis.com/database/mysql/threads/threads_connected' and correlate with CPU utilization and query latency.
Option D is correct because the 'threads_connected' metric directly measures the number of active connections to the MySQL instance. Correlating this with CPU utilization and query latency allows you to pinpoint whether a sudden spike in connections is causing resource contention and degraded query performance, which is the exact scenario described.
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.
- ✗
Monitor 'cloudsql.googleapis.com/network/received_bytes_count' and compare with connection count.
Why it's wrong here
Network bytes received is a throughput metric, not a direct indicator of connection spikes.
- ✗
Monitor 'cloudsql.googleapis.com/database/mysql/replication/seconds_behind_master' and compare with query latency.
- ✗
Monitor 'cloudsql.googleapis.com/instance/uptime' and check for instance restarts during degradation.
Why it's wrong here
Uptime indicates availability, not connection spikes or performance.
- ✓
Monitor 'cloudsql.googleapis.com/database/mysql/threads/threads_connected' and correlate with CPU utilization and query latency.
Why this is correct
Threads connected directly indicates active connections, and correlating with CPU and latency helps identify the impact.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse network metrics (like bytes received) or replication metrics with direct indicators of connection-related performance issues, rather than focusing on the thread count and its impact on CPU and query latency.
Detailed technical explanation
How to think about this question
Under the hood, MySQL uses a thread-per-connection model; each new connection spawns a thread that consumes CPU and memory. When 'threads_connected' spikes, the MySQL thread scheduler and OS context switching overhead increase, directly impacting query latency. In Cloud SQL, you can use Cloud Monitoring to create a custom dashboard overlaying 'threads_connected', 'cpu/utilization', and 'database/mysql/query_latency' to visually confirm the correlation.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
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 PCDE question test?
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: Monitor 'cloudsql.googleapis.com/database/mysql/threads/threads_connected' and correlate with CPU utilization and query latency. — Option D is correct because the 'threads_connected' metric directly measures the number of active connections to the MySQL instance. Correlating this with CPU utilization and query latency allows you to pinpoint whether a sudden spike in connections is causing resource contention and degraded query performance, which is the exact scenario described.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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: Jun 11, 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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