The answer is to enable the 'Fast Combine' option in the Power Query privacy settings. This works because Fast Combine tells Power BI to ignore data source privacy levels, allowing the query engine to merge data from different sources—or in this case, a remote SQL Server—without performing costly isolation checks. By removing these overheads, Power BI can push more transformation work back to the source server through query folding, drastically reducing the number of round trips and improving data refresh performance without changing the data source itself. On the PL-300 exam, this scenario tests your understanding of Power Query’s privacy architecture and performance tuning, often appearing as a distractor alongside options like changing the gateway or increasing parallelism. A common trap is assuming you must move the database or use incremental refresh, but Fast Combine is the direct fix for remote-source latency. Memory tip: think “Fast Combine = Fast Connection” by removing privacy barriers.
PL-300 Prepare the data Practice Question
This PL-300 practice question tests your understanding of prepare 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.
You have a Power BI dataset that uses a SQL Server data source. The SQL Server database is located in a different region, causing slow refresh performance. You need to improve the data refresh performance without changing the data source. What should you do?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable the 'Fast Combine' option in the Power Query privacy settings.
Option D is correct because enabling the 'Fast Combine' option in Power Query privacy settings allows Power BI to ignore privacy levels for data sources, which can significantly improve query performance by enabling more efficient query folding and reducing the overhead of separate data source isolation checks. This is particularly beneficial when dealing with a remote SQL Server database, as it minimizes the number of round trips and data transformations required during refresh.
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.
✗
Change the storage mode to DirectQuery to reduce data movement.
Why it's wrong here
DirectQuery may slow down report performance and does not improve refresh speed.
✗
Increase the scheduled refresh frequency to reduce the amount of data loaded each time.
Why it's wrong here
Refresh frequency does not affect the amount of data loaded per refresh; incremental refresh would.
✗
Install an on-premises data gateway to reduce latency.
Why it's wrong here
A gateway is for connecting to on-premises sources, not for improving performance across regions.
✓
Enable the 'Fast Combine' option in the Power Query privacy settings.
Why this is correct
Fast Combine can improve performance by bypassing privacy checks, but may have security implications.
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 often confuse 'Fast Combine' with a security or data protection feature, not realizing it is a performance optimization that trades privacy enforcement for faster query folding and reduced data transfer.
Detailed technical explanation
How to think about this question
The 'Fast Combine' option bypasses the Power Query engine's privacy-level checks, which normally enforce data isolation between sources (e.g., Public, Organizational, and Private). When privacy levels are enforced, the engine may prevent query folding and instead load data into the mashup engine for separate processing, increasing memory and network overhead. By enabling Fast Combine, Power BI can push more transformations to the SQL Server (query folding), reducing data movement and improving refresh speed, especially over high-latency connections.
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.
Prepare the data — This question tests Prepare the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable the 'Fast Combine' option in the Power Query privacy settings. — Option D is correct because enabling the 'Fast Combine' option in Power Query privacy settings allows Power BI to ignore privacy levels for data sources, which can significantly improve query performance by enabling more efficient query folding and reducing the overhead of separate data source isolation checks. This is particularly beneficial when dealing with a remote SQL Server database, as it minimizes the number of round trips and data transformations required during refresh.
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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