- A
Create a view over the table
Why wrong: Views do not affect storage or scan costs.
- B
Create a materialized view with a filter on date
Why wrong: Materialized views still require the underlying table partitions to be scanned.
- C
Cluster the table by date column
Why wrong: Clustering orders data but does not prune partitions.
- D
Partition the table by date column
Partition pruning reduces data scanned.
Question 935 of 1,000
BigQuery Partitioning for Date Range Query Performance
This PCDE practice question tests your understanding of design and implement database schemas. 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 BigQuery table stores daily sales data. The team commonly queries data for a specific date range. Which schema optimization will reduce query cost and improve performance?
Quick Answer
The correct choice is to partition the table by a date column. Partitioning by date allows BigQuery to perform partition pruning, meaning it scans only the partitions that match the specified date range rather than the entire table, which directly reduces query cost and improves performance for date range queries. On the Google Professional Cloud Database Engineer exam, this scenario tests your understanding of schema optimization for time-series data, a common pattern in real-world workloads. A frequent trap is choosing clustering instead, but while clustering sorts data within partitions, partitioning is the primary mechanism for eliminating irrelevant data at the scan level. Remember the memory tip: “Partition to prune, cluster to sort”—partitioning first cuts the data volume, then clustering refines the order within those cuts.
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
✓
Partition the table by date column
Partitioning the table by the date column allows BigQuery to prune entire partitions when querying a specific date range, drastically reducing the amount of data scanned. Since BigQuery charges by the bytes processed, this directly lowers query cost and improves performance by reading only the relevant partitions.
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.
- ✗
Create a view over the table
Why it's wrong here
Views do not affect storage or scan costs.
- ✗
Create a materialized view with a filter on date
Why it's wrong here
Materialized views still require the underlying table partitions to be scanned.
- ✗
Cluster the table by date column
Why it's wrong here
Clustering orders data but does not prune partitions.
- ✓
Partition the table by date column
Why this is correct
Partition pruning reduces data scanned.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
In Google Cloud BigQuery, partitioning by date enables partition pruning that reduces data scanned, directly lowering cost. Candidates often confuse this with clustering, which only reorders data within a partition and does not independently reduce scanned bytes.
Detailed technical explanation
How to think about this question
BigQuery partitions are implemented as separate storage blocks (e.g., one per day), and the query engine uses the WHERE clause to perform partition pruning at the metadata level before any data is read. This is similar to Hive-style partitioning but managed automatically; for time-based queries, partitioning by date can reduce scanned bytes by orders of magnitude compared to clustering alone. A real-world scenario is a multi-terabyte sales table where a daily query for the last 7 days would scan only 7 partitions instead of the entire table, saving costs and latency.
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 PCDE question test?
Design and implement database schemas — This question tests Design and implement database schemas — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Partition the table by date column — Partitioning the table by the date column allows BigQuery to prune entire partitions when querying a specific date range, drastically reducing the amount of data scanned. Since BigQuery charges by the bytes processed, this directly lowers query cost and improves performance by reading only the relevant partitions.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
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