- A
Redesign the primary key to distribute writes evenly across splits.
Even distribution reduces contention.
- B
Increase the mutation size to 10 KB to reduce number of writes.
Why wrong: Larger mutations don't reduce contention; they increase load.
- C
Scale the instance to 2 nodes.
More nodes increase write capacity.
- D
Use a monotonically increasing primary key to improve index performance.
Why wrong: Monotonically increasing keys cause hotspots.
- E
Split the table into multiple smaller tables.
Why wrong: Doesn't increase throughput.
Question 279 of 1,000
PCDOE Design and Plan Database Solutions Practice Question
This PCDOE practice question tests your understanding of design and plan database solutions. 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.
A Cloud Spanner instance has a single node and is experiencing high write contention. The workload is 3000 writes per second with 2 KB mutations. Which two changes would improve write throughput? (Choose TWO.)
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
✓
Redesign the primary key to distribute writes evenly across splits.
Option A is correct because high write contention in Cloud Spanner often stems from hotspotting, where all writes target the same split. By redesigning the primary key to distribute writes evenly across splits, you reduce contention and improve throughput. This is a fundamental design pattern for Spanner's distributed architecture.
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.
- ✓
Redesign the primary key to distribute writes evenly across splits.
Why this is correct
Even distribution reduces contention.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the mutation size to 10 KB to reduce number of writes.
Why it's wrong here
Larger mutations don't reduce contention; they increase load.
- ✓
Scale the instance to 2 nodes.
Why this is correct
More nodes increase write capacity.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a monotonically increasing primary key to improve index performance.
Why it's wrong here
Monotonically increasing keys cause hotspots.
- ✗
Split the table into multiple smaller tables.
Why it's wrong here
Doesn't increase throughput.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that scaling nodes alone solves write contention, but the trap here is that while adding nodes (Option C) increases total throughput capacity, it does not fix hotspotting caused by a poorly designed primary key—both changes are needed for optimal write throughput.
Detailed technical explanation
How to think about this question
Cloud Spanner uses a distributed, Paxos-based architecture where each split (a contiguous range of rows) is replicated and served by a separate set of nodes. Write contention occurs when multiple transactions try to modify rows in the same split, causing lock conflicts and retries. Redesigning the primary key to use a hash prefix or a random element (e.g., a UUID or a hash of the user ID) ensures writes are spread across splits, leveraging Spanner's automatic split management and reducing lock contention.
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 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.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Design and Plan Database Solutions — This question tests Design and Plan Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Redesign the primary key to distribute writes evenly across splits. — Option A is correct because high write contention in Cloud Spanner often stems from hotspotting, where all writes target the same split. By redesigning the primary key to distribute writes evenly across splits, you reduce contention and improve throughput. This is a fundamental design pattern for Spanner's distributed architecture.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Jul 4, 2026
This PCDOE 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 PCDOE exam.
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