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Managing application performance monitoring →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that missing database indexes are the most likely cause, and you should use Cloud SQL Insights to identify slow queries and pinpoint those missing indexes. This is correct because the symptoms—high app server CPU, low database CPU at only 30%, and Cloud Trace showing queries consuming most of the application’s wait time—classically indicate inefficient, full-table scans rather than a resource bottleneck on the database itself. On the Google Professional Cloud Developer exam, this scenario tests your ability to differentiate between application-layer and database-layer performance issues, with a common trap being to scale the database instance when the real fix is query optimization. Cloud SQL Insights specifically surfaces query execution plans and wait events to reveal missing indexes, making it the targeted diagnostic tool. Memory tip: when database CPU is low but app servers are struggling, think “low CPU, high wait—indexes are late.”

PCD Managing application performance monitoring Practice Question

This PCD practice question tests your understanding of managing application performance monitoring. 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 company runs a multi-tier application on Compute Engine with a Cloud SQL backend. Recently, during peak hours, users report slow page loads. Cloud Monitoring shows high CPU on the app servers, but no memory pressure. Cloud Trace shows that the application spends most of its time waiting for database queries. The Cloud SQL instance is a high-memory machine type with 16 vCPUs and 64 GB RAM, but CPU utilization on the database is only 30%. There are no slow query alerts. What is the most likely cause and what should you do?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice

Full question →

A
The database lacks indexes. Use Cloud SQL Query Insights to identify missing indexes.
Missing indexes force full table scans, causing slow queries. Query Insights can reveal the specific slow queries and suggest indexes.
B
The application is performing unnecessary queries. Add caching with Memorystore.
Why wrong: Caching could reduce load, but the root cause is likely slow queries due to lack of indexes, not unnecessary queries. Traces show waiting on queries, not redundant ones.
C
The database connection pool is exhausted. Increase the maximum number of connections.
Why wrong: Connection pool exhaustion would likely cause connection errors, not uniformly slow queries; also, database CPU is low, not a symptom of pool issues.
D
The Cloud SQL instance is under-provisioned. Upgrade to a larger machine type.
Why wrong: Database CPU is only 30%, indicating it is not compute-bound; upgrading would not address the root cause of slow queries.

Full breakdown with real-world context →

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

✓

The database lacks indexes. Use Cloud SQL Query Insights to identify missing indexes.

The symptoms—high app server CPU, low database CPU, and queries consuming most of the application’s wait time—point to inefficient queries due to missing indexes. Cloud SQL Query Insights can identify these missing indexes by analyzing query execution plans and wait events. Adding appropriate indexes reduces query execution time, lowering app server CPU usage and resolving the slow page loads.

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.

✓
The database lacks indexes. Use Cloud SQL Query Insights to identify missing indexes.
Why this is correct
Missing indexes force full table scans, causing slow queries. Query Insights can reveal the specific slow queries and suggest indexes.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The application is performing unnecessary queries. Add caching with Memorystore.
Why it's wrong here
Caching could reduce load, but the root cause is likely slow queries due to lack of indexes, not unnecessary queries. Traces show waiting on queries, not redundant ones.
✗
The database connection pool is exhausted. Increase the maximum number of connections.
Why it's wrong here
Connection pool exhaustion would likely cause connection errors, not uniformly slow queries; also, database CPU is low, not a symptom of pool issues.
✗
The Cloud SQL instance is under-provisioned. Upgrade to a larger machine type.
Why it's wrong here
Database CPU is only 30%, indicating it is not compute-bound; upgrading would not address the root cause of slow queries.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that high app server CPU always means the app server is the bottleneck, when in fact the CPU is consumed waiting for slow database queries caused by missing indexes.

Trap categories for this question

Command / output trap
Caching could reduce load, but the root cause is likely slow queries due to lack of indexes, not unnecessary queries. Traces show waiting on queries, not redundant ones.

Detailed technical explanation

How to think about this question

Missing indexes force full table scans, which increase query latency and consume app server CPU while the database waits on I/O. Cloud SQL Query Insights uses the `performance_schema` to capture query execution statistics and index recommendations. In a real-world scenario, a missing composite index on a frequently filtered column can cause queries to scan millions of rows, even though the database CPU remains low because the bottleneck is I/O wait, not compute.

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.

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FAQ

Questions learners often ask

What does this PCD question test?

Managing application performance monitoring — This question tests Managing application performance monitoring — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The database lacks indexes. Use Cloud SQL Query Insights to identify missing indexes. — The symptoms—high app server CPU, low database CPU, and queries consuming most of the application’s wait time—point to inefficient queries due to missing indexes. Cloud SQL Query Insights can identify these missing indexes by analyzing query execution plans and wait events. Adding appropriate indexes reduces query execution time, lowering app server CPU usage and resolving the slow page loads.

What should I do if I get this PCD 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

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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Same concept, more angles

1 more ways this is tested on PCD

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. An application uses Cloud SQL and is experiencing slow query performance. The team wants to monitor query latency and identify slow queries. Which Google Cloud tool should they use?

medium

✓ A.Cloud SQL Insights
B.Cloud Debugger
C.Cloud Monitoring
D.Cloud Trace

Why A: Cloud SQL Insights is the correct tool because it is specifically designed to provide detailed query performance diagnostics for Cloud SQL databases. It captures query latency, execution plans, and wait events, enabling teams to identify and troubleshoot slow queries directly within the Cloud SQL console without additional configuration.

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Question Discussion

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This PCD 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 PCD exam.