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 are running a production workload on Cloud Bigtable and notice that read latency has increased. Upon reviewing the monitoring dashboard, you see that CPU utilization is below 50% but the number of active tablets is high. What is the most likely cause of the increased read latency?
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
There are too many tablets, causing increased metadata operations and slower reads.
In Cloud Bigtable, each tablet is a contiguous range of rows managed by a tablet server. When the number of active tablets is high, the tablet server must perform more metadata operations (e.g., splitting, merging, and serving multiple tablets) which increases per-request overhead and can degrade read latency. This is true even when CPU utilization is below 50%, because the overhead is not purely CPU-bound but involves increased I/O and coordination.
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.
✗
Read requests are being throttled due to exceeding IOPS limits.
Why it's wrong here
Throttling would increase CPU, but CPU is low.
✓
There are too many tablets, causing increased metadata operations and slower reads.
Why this is correct
Excessive tablets increase the overhead of metadata lookups and tablet splitting, leading to higher latency.
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.
✗
A hot node is throttling read requests.
Why it's wrong here
CPU utilization is below 50%, so a hot node is unlikely.
✗
The cluster is underprovisioned, causing resource contention.
Why it's wrong here
Underprovisioning would cause high CPU, not low CPU.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that high tablet count is always beneficial for parallelism, when in fact it can degrade performance due to metadata overhead, especially when CPU is not the bottleneck.
Detailed technical explanation
How to think about this question
Cloud Bigtable splits tablets automatically based on size (default ~256 MB) and load. A high number of active tablets can cause the tablet server to perform more frequent compaction and metadata lookups, increasing the latency of individual reads. In production, this often occurs after a bulk load or schema change that creates many small tablets, and the solution is to rebalance or merge tablets using the `cbt` tool or by adjusting the initial split configuration.
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 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
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.
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: There are too many tablets, causing increased metadata operations and slower reads. — In Cloud Bigtable, each tablet is a contiguous range of rows managed by a tablet server. When the number of active tablets is high, the tablet server must perform more metadata operations (e.g., splitting, merging, and serving multiple tablets) which increases per-request overhead and can degrade read latency. This is true even when CPU utilization is below 50%, because the overhead is not purely CPU-bound but involves increased I/O and coordination.
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: "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.
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Question Discussion
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