- A
Set up cluster replication to a secondary cluster
Why wrong: Replication copies data, it does not remove it.
- B
Enable compaction on the table
Why wrong: Compaction reorganizes storage but does not delete data.
- C
Configure a garbage collection policy based on time or number of versions
Garbage collection automatically removes old or deleted data, reducing storage.
- D
Use IAM conditions to restrict write access
Why wrong: IAM controls access, not data retention.
Question 39 of 999
Design Scalable and Highly Available Cloud Database Solutions →mediumMultiple ChoiceObjective-mapped
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. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company uses Cloud Bigtable for AdTech clickstream data. They notice that some tables have many deleted rows and the storage cost is increasing. What should they configure to automatically remove deleted data and reduce storage?
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
✓
Configure a garbage collection policy based on time or number of versions
Cloud Bigtable automatically compacts data in the background, but deleted rows are not immediately removed; they remain as tombstones until a garbage collection policy is applied. By configuring a garbage collection policy based on time or number of versions, you instruct Bigtable to permanently delete expired data and reclaim storage space, reducing costs.
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.
- ✗
Set up cluster replication to a secondary cluster
Why it's wrong here
Replication copies data, it does not remove it.
- ✗
Enable compaction on the table
Why it's wrong here
Compaction reorganizes storage but does not delete data.
- ✓
Configure a garbage collection policy based on time or number of versions
Why this is correct
Garbage collection automatically removes old or deleted data, reducing storage.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use IAM conditions to restrict write access
Why it's wrong here
IAM controls access, not data retention.
Common exam traps
Common exam trap: answer the scenario, not the keyword
A common misconception is that compaction alone removes deleted data, but without a garbage collection policy, tombstones persist and storage is not reclaimed.
Detailed technical explanation
How to think about this question
In Cloud Bigtable, deleted rows are marked with a tombstone that is only removed during a major compaction, but major compactions are triggered automatically and may not run frequently on tables with many deletions. A garbage collection policy (e.g., max age or max versions) ensures that old data and tombstones are pruned during the next compaction cycle, directly reducing the number of SSTables and storage footprint. In real-world AdTech scenarios, high-volume clickstream data often has a short retention window, so a time-based policy (e.g., 30 days) is critical to prevent unbounded storage growth.
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
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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: Configure a garbage collection policy based on time or number of versions — Cloud Bigtable automatically compacts data in the background, but deleted rows are not immediately removed; they remain as tombstones until a garbage collection policy is applied. By configuring a garbage collection policy based on time or number of versions, you instruct Bigtable to permanently delete expired data and reclaim storage space, reducing costs.
What should I do if I get this PCD 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 →
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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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