- A
Keep the auto-increment key but use bit-reversal
Why wrong: Bit-reversal can help distribute writes but does not guarantee hotspot avoidance and makes ordering on the original integer difficult.
- B
Use a composite primary key with a hash prefix followed by the UUID
Why wrong: A composite key with a hash prefix and UUID distributes writes, but ordering is based on the UUID, not the original integer. Unless the UUID is generated to preserve the original order (e.g., via ULID), this does not support ORDER BY on the original integer as required.
- C
Use the UUID as the primary key and create a secondary index on the original integer
Correct. UUID primary key avoids hotspots, and a secondary index on the original integer provides the needed ordering.
- D
Use a monotonically increasing custom ID and rely on Spanner's split management
Why wrong: Monotonically increasing keys cause hotspots in Spanner even with automatic split management, so this does not avoid hotspots.
PCDOE Hotspotting 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. A key principle to apply: hotspotting. 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 team is migrating a MySQL OLTP database to Cloud Spanner. The existing schema uses auto-increment primary keys. They plan to convert them to STRING columns with UUIDs. However, the application also relies on ORDER BY on the original integer key. How should they preserve ordering while avoiding hotspots in Spanner?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
Use the UUID as the primary key and create a secondary index on the original integer
Using UUID as the primary key avoids hotspotting because UUIDs are random and distribute writes evenly across splits. Creating a secondary index on the original integer key allows efficient ORDER BY queries on that column. While the secondary index may experience some hotspotting due to monotonically increasing values, Spanner's automatic split management can mitigate this, and the approach meets both requirements: hotspot avoidance on the primary key and ordering capability on the original integer.
Key principle: Hotspotting
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Keep the auto-increment key but use bit-reversal
Why it's wrong here
Bit-reversal can help distribute writes but does not guarantee hotspot avoidance and makes ordering on the original integer difficult.
- ✗
Use a composite primary key with a hash prefix followed by the UUID
Why it's wrong here
A composite key with a hash prefix and UUID distributes writes, but ordering is based on the UUID, not the original integer. Unless the UUID is generated to preserve the original order (e.g., via ULID), this does not support ORDER BY on the original integer as required.
- ✓
Use the UUID as the primary key and create a secondary index on the original integer
Why this is correct
Correct. UUID primary key avoids hotspots, and a secondary index on the original integer provides the needed ordering.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Hotspotting
- ✗
Use a monotonically increasing custom ID and rely on Spanner's split management
Why it's wrong here
Monotonically increasing keys cause hotspots in Spanner even with automatic split management, so this does not avoid hotspots.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often think a composite key with a hash prefix and a sortable UUID is the best solution, but this does not preserve ordering by the original integer unless the UUID is specifically generated to reflect that order. The secondary index approach directly supports ordering on the original key.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Hotspotting
- Secondary Index
- UUID Primary Key
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
Hotspotting
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.
Review hotspotting, then practise related PCDOE questions on the same topic to reinforce the concept.
- →
Design and Plan Database Solutions — study guide chapter
Learn the concepts, then practise the questions
- →
Design and Plan Database Solutions practice questions
Targeted practice on this topic area only
- →
All PCDOE questions
1,000 questions across all exam domains
- →
Google Professional Cloud DevOps Engineer study guide
Full concept coverage aligned to exam objectives
- →
PCDOE practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related PCDOE practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Design and Plan Database Solutions practice questions
Practise PCDOE questions linked to Design and Plan Database Solutions.
Manage Database Solutions practice questions
Practise PCDOE questions linked to Manage Database Solutions.
Migrate Database Solutions practice questions
Practise PCDOE questions linked to Migrate Database Solutions.
Design for Reliability, Scalability, and Disaster Recovery practice questions
Practise PCDOE questions linked to Design for Reliability, Scalability, and Disaster Recovery.
Bootstrapping a Google Cloud organization for DevOps practice questions
Practise PCDOE questions linked to Bootstrapping a Google Cloud organization for DevOps.
Managing service incidents practice questions
Practise PCDOE questions linked to Managing service incidents.
Managing Google Cloud costs practice questions
Practise PCDOE questions linked to Managing Google Cloud costs.
Building and implementing CI/CD pipelines practice questions
Practise PCDOE questions linked to Building and implementing CI/CD pipelines.
Implementing service monitoring strategies practice questions
Practise PCDOE questions linked to Implementing service monitoring strategies.
Optimizing service performance practice questions
Practise PCDOE questions linked to Optimizing service performance.
PCDOE fundamentals practice questions
Practise PCDOE questions linked to PCDOE fundamentals.
PCDOE scenario practice questions
Practise PCDOE questions linked to PCDOE scenario.
Practice this exam
Start a free PCDOE practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this PCDOE question test?
Design and Plan Database Solutions — This question tests Design and Plan Database Solutions — Hotspotting.
What is the correct answer to this question?
The correct answer is: Use the UUID as the primary key and create a secondary index on the original integer — Using UUID as the primary key avoids hotspotting because UUIDs are random and distribute writes evenly across splits. Creating a secondary index on the original integer key allows efficient ORDER BY queries on that column. While the secondary index may experience some hotspotting due to monotonically increasing values, Spanner's automatic split management can mitigate this, and the approach meets both requirements: hotspot avoidance on the primary key and ordering capability on the original integer.
What should I do if I get this PCDOE question wrong?
Review hotspotting, then practise related PCDOE questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Hotspotting
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More PCDOE practice questions
- Order the steps to configure a VPC Network Peering between two projects.
- Refer to the exhibit. The Cloud Build fails with a permission error. The Cloud Build service account has roles/cloudbuil…
- A company is setting up a new Google Cloud organization. They want to ensure that all projects inherit common IAM polici…
- A DevOps team is bootstrapping their Google Cloud organization and wants to enable Infrastructure as Code (IaC) using Te…
- To securely manage secrets (e.g., API keys) used in Cloud Build pipelines, which service should be used?
- A DevOps engineer needs to set up a centralized logging solution for multiple projects. They want to store logs in a Big…
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.