PCDE Practice Question: Define data structures and implement SQL for Business Intelligence
This PCDE practice question tests your understanding of define data structures and implement sql for business intelligence. 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.
Which TWO are best practices for designing a star schema in BigQuery for BI? (Choose two.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Store dimension attributes in a single denormalized dimension table instead of multiple normalized tables.
Option A is correct because in BigQuery, storing dimension attributes in a single denormalized dimension table (star schema) reduces the number of joins required in BI queries, improving query performance and simplifying SQL. BigQuery's columnar storage and distributed architecture handle denormalized dimensions efficiently, avoiding the overhead of multiple normalized tables that would require complex joins and slow down analytical queries.
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.
✓
Store dimension attributes in a single denormalized dimension table instead of multiple normalized tables.
Why this is correct
Denormalization reduces join complexity.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Partition fact tables by low-cardinality columns like gender.
Why it's wrong here
Low-cardinality columns are better for clustering than partitioning.
✗
Pre-aggregate all measures at every possible grain in the fact table.
Why it's wrong here
Over-aggregation reduces query flexibility and increases storage.
✗
Avoid using joins entirely by storing all data in one wide table.
Why it's wrong here
Wide tables can be less efficient and harder to maintain.
✓
Use surrogate keys for dimension tables instead of natural keys.
Why this is correct
Surrogate keys provide a stable join column.
Clue confirmation
The clue word "best" 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
Google Cloud often tests the misconception that denormalization is always bad, but in BigQuery's architecture, denormalized dimension tables are a best practice for BI workloads, unlike traditional OLTP databases.
Detailed technical explanation
How to think about this question
In BigQuery, star schema design leverages clustering on dimension keys to co-locate related rows, reducing shuffle during joins. Denormalized dimension tables also benefit from BigQuery's automatic compression and columnar storage, where repeated attribute values are stored efficiently. A real-world scenario is a sales fact table joined with a customer dimension; storing customer attributes in a single table allows clustering on customer_id, making queries like 'total sales by region' fast without multiple joins.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Define data structures and implement SQL for Business Intelligence — This question tests Define data structures and implement SQL for Business Intelligence — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Store dimension attributes in a single denormalized dimension table instead of multiple normalized tables. — Option A is correct because in BigQuery, storing dimension attributes in a single denormalized dimension table (star schema) reduces the number of joins required in BI queries, improving query performance and simplifying SQL. BigQuery's columnar storage and distributed architecture handle denormalized dimensions efficiently, avoiding the overhead of multiple normalized tables that would require complex joins and slow down analytical queries.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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