- A
Add a hash prefix or salt to the beginning of the row key.
Salting distributes writes across tablets.
- B
Put the most frequently filtered fields first in the row key.
Why wrong: That optimizes reads, not write distribution.
- C
Use reverse timestamp to keep recent data first.
Why wrong: Doesn't prevent hotspotting; can even cause it if many writes happen at the same time.
- D
Use device ID as the sole row key prefix to group data by device.
Why wrong: High-volume devices cause hotspots.
- E
Use a hash of the device ID to randomize the row key.
Hashing ensures even distribution.
Question 258 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 team is designing a Bigtable schema for a real-time fraud detection system. The row key includes device ID and timestamp. They need to avoid hotspotting during high write periods. Which two row key design patterns help achieve this? (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
✓
Add a hash prefix or salt to the beginning of the row key.
Option A is correct because adding a hash prefix or salt to the beginning of the row key distributes writes across multiple tablet servers, preventing hotspotting on a single node. In Bigtable, row keys are sorted lexicographically, so sequential device IDs or timestamps would cause all writes to hit the same tablet. A hash prefix ensures even distribution of write load.
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.
- ✓
Add a hash prefix or salt to the beginning of the row key.
Why this is correct
Salting distributes writes across tablets.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Put the most frequently filtered fields first in the row key.
Why it's wrong here
That optimizes reads, not write distribution.
- ✗
Use reverse timestamp to keep recent data first.
Why it's wrong here
Doesn't prevent hotspotting; can even cause it if many writes happen at the same time.
- ✗
Use device ID as the sole row key prefix to group data by device.
Why it's wrong here
High-volume devices cause hotspots.
- ✓
Use a hash of the device ID to randomize the row key.
Why this is correct
Hashing ensures even distribution.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between patterns that optimize reads (like putting filtered fields first) versus patterns that prevent write hotspotting (like salting or hashing), and candidates mistakenly choose read-optimization patterns for a write-heavy scenario.
Detailed technical explanation
How to think about this question
Bigtable splits row key ranges into tablets, each served by a single tablet server. Without salting, sequential timestamps or device IDs cause all new writes to land on the last tablet, overwhelming it. A hash prefix (e.g., MD5 or CRC32 of the device ID) spreads writes uniformly across the key space. Option E (hash of device ID) achieves the same effect by randomizing the prefix, though it may scatter related reads; a common pattern is to use a hash prefix followed by the original device ID and timestamp to balance write distribution and read locality.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a hash prefix or salt to the beginning of the row key. — Option A is correct because adding a hash prefix or salt to the beginning of the row key distributes writes across multiple tablet servers, preventing hotspotting on a single node. In Bigtable, row keys are sorted lexicographically, so sequential device IDs or timestamps would cause all writes to hit the same tablet. A hash prefix ensures even distribution of write load.
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
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 →
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.