The answer is to filter rows in Power Query to remove unnecessary data early in the transformation, split the large CSV file into smaller manageable parts, and use an efficient file format like Parquet instead of CSV. These three practices are correct because Power BI’s performance hinges on reducing the data volume as early as possible in the ETL process; filtering rows and splitting the file minimize memory pressure during import, while Parquet’s columnar storage and compression drastically reduce I/O and load times compared to raw CSV. On the Microsoft Power BI Data Analyst PL-300 exam, this question tests your understanding of data source optimization and the Power Query engine’s query folding capabilities—a common trap is assuming the on-premises data gateway is needed for cloud storage like Azure Blob, but it is not, and another is importing all columns instead of selecting only needed ones. Remember the mnemonic “FSP” for Filter, Split, Parquet to recall the three pillars of large file performance.
PL-300 Prepare the data Practice Question
This PL-300 practice question tests your understanding of prepare the data. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 are connecting to a large CSV file (10 GB) stored in Azure Blob Storage. You need to load the data into Power BI with optimal performance. Which THREE practices should you follow? (Choose three.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Parquet format instead of CSV if possible.
Options A, C, and E are correct because splitting the file, filtering rows early, and using an efficient file format improve performance. Option B is incorrect because the Power BI service can handle large files, but the gateway is not needed for cloud storage. Option D is incorrect because importing all columns reduces performance; you should select only needed columns.
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 Parquet format instead of CSV if possible.
Why this is correct
Parquet is a columnar format that is more efficient for large data volumes.
Related concept
Read the scenario before looking for a memorised answer.
✗
Import all columns and use Power BI to hide unused ones.
Why it's wrong here
Importing unnecessary columns increases data load and memory usage.
✓
Split the large CSV file into multiple smaller files in the same folder.
Why this is correct
Power Query can combine multiple files efficiently; smaller files reduce memory pressure.
Related concept
Read the scenario before looking for a memorised answer.
✓
Filter rows in Power Query to remove unnecessary data early in the transformation.
Why this is correct
Early filtering reduces data volume and improves performance.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the on-premises data gateway to connect to Azure Blob Storage.
Why it's wrong here
The gateway is for on-premises data sources; cloud sources can be connected directly.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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: Use Parquet format instead of CSV if possible. — Options A, C, and E are correct because splitting the file, filtering rows early, and using an efficient file format improve performance. Option B is incorrect because the Power BI service can handle large files, but the gateway is not needed for cloud storage. Option D is incorrect because importing all columns reduces performance; you should select only needed columns.
What should I do if I get this PL-300 question wrong?
Identify which PL-300 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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