- A
Use logical storage billing and partition the table by date; older data automatically moves to long-term storage after 90 days.
Why wrong: Logical storage billing is less cost-effective for large, highly compressed data. Long-term storage provides some cost savings but not optimal.
- B
Use Bigtable for recent data and BigQuery for historical data, with a scheduled transfer between them.
Why wrong: This adds operational complexity and Bigtable costs may not be lower; query interface changes.
- C
Export data older than 30 days to Cloud Storage as Avro files and delete them from BigQuery; query them externally when needed.
Why wrong: Querying external data is slower and incurs additional costs; management is complex.
- D
Use physical storage billing, partition the table by ingestion date, cluster on frequently used columns, and set an expiration on partitions older than 6 months to move them to long-term storage.
Physical billing with long-term storage after 90 days of no modifications reduces costs. Partitioning and clustering optimize performance on recent data.
Quick Answer
The correct approach is to use physical storage billing, partition the table by ingestion date, cluster on frequently used columns, and set a partition expiration on partitions older than 6 months. This strategy works because physical storage billing in BigQuery separates costs into active and long-term tiers, and partition expiration automatically moves older data into the cheaper long-term storage tier without manual intervention. Partitioning by ingestion date ensures that recent, frequently accessed data stays in fast, active storage, while clustering on commonly filtered columns maintains query performance on that hot data. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of BigQuery’s tiered storage model and the interplay between partition expiration and billing mode—a common trap is assuming logical storage billing or manual table copies are needed. Remember the mnemonic: “Partition, Cluster, Expire, and Bill Physical” to lock in the four pillars of cost optimization.
PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. 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 Database Engineer is designing a tiered storage strategy for a large BigQuery dataset. The dataset contains data that is accessed frequently for the first 30 days, moderately for the next 6 months, and rarely after that. The engineer wants to minimize overall storage cost while maintaining fast query performance on recent data. Which approach should the engineer take?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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 physical storage billing, partition the table by ingestion date, cluster on frequently used columns, and set an expiration on partitions older than 6 months to move them to long-term storage.
Option D is correct because physical storage billing in BigQuery charges separately for active and long-term storage, and setting a partition expiration on partitions older than 6 months automatically moves that data to long-term storage at a lower cost. Partitioning by ingestion date and clustering on frequently used columns ensures fast query performance on recent data while minimizing overall storage 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.
- ✗
Use logical storage billing and partition the table by date; older data automatically moves to long-term storage after 90 days.
Why it's wrong here
Logical storage billing is less cost-effective for large, highly compressed data. Long-term storage provides some cost savings but not optimal.
- ✗
Use Bigtable for recent data and BigQuery for historical data, with a scheduled transfer between them.
Why it's wrong here
This adds operational complexity and Bigtable costs may not be lower; query interface changes.
- ✗
Export data older than 30 days to Cloud Storage as Avro files and delete them from BigQuery; query them externally when needed.
Why it's wrong here
Querying external data is slower and incurs additional costs; management is complex.
- ✓
Use physical storage billing, partition the table by ingestion date, cluster on frequently used columns, and set an expiration on partitions older than 6 months to move them to long-term storage.
Why this is correct
Physical billing with long-term storage after 90 days of no modifications reduces costs. Partitioning and clustering optimize performance on recent data.
Clue confirmation
The clue words "first", "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse logical and physical storage billing, assuming that logical billing automatically provides long-term storage discounts, when in fact only physical billing has separate active and long-term storage tiers with different pricing.
Detailed technical explanation
How to think about this question
BigQuery's physical storage billing model separates storage costs into active (data modified in the last 90 days) and long-term (data not modified for 90+ days) tiers, with long-term storage being approximately 50% cheaper. Partition expiration on a table automatically deletes partitions older than the specified duration, but in this scenario, setting an expiration on partitions older than 6 months triggers the move to long-term storage because the data is not modified after ingestion, so it becomes eligible for the lower rate after 90 days of no modifications.
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 PCDE question test?
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use physical storage billing, partition the table by ingestion date, cluster on frequently used columns, and set an expiration on partitions older than 6 months to move them to long-term storage. — Option D is correct because physical storage billing in BigQuery charges separately for active and long-term storage, and setting a partition expiration on partitions older than 6 months automatically moves that data to long-term storage at a lower cost. Partitioning by ingestion date and clustering on frequently used columns ensures fast query performance on recent data while minimizing overall storage costs.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first", "minimum / minimize". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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: Jun 11, 2026
This PCDE 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 PCDE exam.
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