This PL-300 practice question tests your understanding of model the data. 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 company has a Power BI semantic model that uses DirectQuery to a SQL Server database. The model contains a large fact table with sales data. Users report that reports using this model are slow. Which design change would most improve query performance?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Remove unnecessary columns from the fact table.
Option C is correct because removing unnecessary columns from the fact table reduces the amount of data that must be transferred from SQL Server to Power BI for each query. In DirectQuery mode, every report interaction sends a query to the source database, so fewer columns mean smaller result sets and faster query execution. This directly addresses the performance bottleneck caused by a large fact table without changing the underlying storage mode.
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.
✗
Remove all relationships between tables.
Why it's wrong here
Removing relationships breaks the model and prevents cross-filtering.
✗
Switch the model to Import mode.
Why it's wrong here
Import mode may not be feasible if data volume is too large.
✓
Remove unnecessary columns from the fact table.
Why this is correct
Reducing columns minimizes data retrieved from source, improving query performance.
Related concept
Read the scenario before looking for a memorised answer.
✗
Disable the 'Reduce queries' option in report settings.
Why it's wrong here
Disabling query reduction would likely degrade performance further.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume switching to Import mode is always the best performance fix, but the question specifically asks for a design change that improves query performance in DirectQuery mode, where reducing column count is a more targeted and less disruptive solution.
Detailed technical explanation
How to think about this question
In DirectQuery mode, Power BI translates report visuals into SQL queries sent to the source database. Each query includes a SELECT clause that lists all columns referenced in the model, even if they are not used in the visual. Removing unnecessary columns from the fact table reduces the width of the result set, lowering network I/O and query execution time at the database level. This is especially impactful when the fact table contains many columns with large data types (e.g., NVARCHAR(MAX)) that are not needed for analysis.
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.
Model the data — This question tests Model the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Remove unnecessary columns from the fact table. — Option C is correct because removing unnecessary columns from the fact table reduces the amount of data that must be transferred from SQL Server to Power BI for each query. In DirectQuery mode, every report interaction sends a query to the source database, so fewer columns mean smaller result sets and faster query execution. This directly addresses the performance bottleneck caused by a large fact table without changing the underlying storage mode.
What should I do if I get this PL-300 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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Question Discussion
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