- A
Use separate tables for each access pattern
Why wrong: Unnecessary complexity; column families within a single table suffice.
- B
Store rarely accessed columns as a JSON string in a single column
Why wrong: Not a recommended practice; still mixes access patterns and adds parsing overhead.
- C
Create two column families: 'core' for frequently accessed columns and 'extended' for rarely accessed columns
This allows efficient reads by reading only the required column family.
- D
Place all columns in a single column family for simplicity
Why wrong: Mixing access patterns in one column family reduces performance as Bigtable reads all columns even if only a few are needed.
Question 190 of 999
PCD Practice Question: Design Scalable and Highly Available Cloud Database Solutions
This PCD practice question tests your understanding of design scalable and highly available cloud 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.
You are tuning a Cloud Bigtable table used for analytics. One column family, 'data', contains both frequently accessed columns (e.g., 'price', 'volume') and rarely accessed columns (e.g., 'raw_json'). To optimize performance and cost, what column family design is recommended?
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
✓
Create two column families: 'core' for frequently accessed columns and 'extended' for rarely accessed columns
Separating columns into different column families based on access patterns is a best practice. Frequently accessed columns should be in one column family (e.g., 'core'), and rarely accessed columns in another (e.g., 'extended'). This allows Bigtable to optimize storage and read performance.
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.
- ✗
Use separate tables for each access pattern
Why it's wrong here
Unnecessary complexity; column families within a single table suffice.
- ✗
Store rarely accessed columns as a JSON string in a single column
Why it's wrong here
Not a recommended practice; still mixes access patterns and adds parsing overhead.
- ✓
Create two column families: 'core' for frequently accessed columns and 'extended' for rarely accessed columns
Why this is correct
This allows efficient reads by reading only the required column family.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Place all columns in a single column family for simplicity
Why it's wrong here
Mixing access patterns in one column family reduces performance as Bigtable reads all columns even if only a few are needed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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FAQ
Questions learners often ask
What does this PCD question test?
Design Scalable and Highly Available Cloud Database Solutions — This question tests Design Scalable and Highly Available Cloud Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create two column families: 'core' for frequently accessed columns and 'extended' for rarely accessed columns — Separating columns into different column families based on access patterns is a best practice. Frequently accessed columns should be in one column family (e.g., 'core'), and rarely accessed columns in another (e.g., 'extended'). This allows Bigtable to optimize storage and read performance.
What should I do if I get this PCD question wrong?
Identify which PCD exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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 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.
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