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 report that uses a dataset with many columns. You want to reduce the dataset size by removing columns that are not used in any report visual. What is the best practice?
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.
Remove the columns in Power Query Editor before loading
Removing columns reduces data loaded into the model.
Use the Q&A feature to exclude columns
Why wrong: Q&A is a natural language query tool, not for column removal.
Apply report-level filters to exclude the columns
Why wrong: Filters do not remove columns from the dataset.
Hide the columns in the model view
Why wrong: Hiding columns does not reduce dataset size.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Remove the columns in Power Query Editor before loading
Option A is correct because removing columns in Power Query Editor before they are loaded into the data model physically excludes them from the dataset, reducing its size and improving performance. This is the only method that prevents unused columns from consuming memory and storage in the in-memory VertiPaq engine.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Remove the columns in Power Query Editor before loading
Why this is correct
Removing columns reduces data loaded into the model.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Use the Q&A feature to exclude columns
Why it's wrong here
Q&A is a natural language query tool, not for column removal.
Apply report-level filters to exclude the columns
Why it's wrong here
Filters do not remove columns from the dataset.
Hide the columns in the model view
Why it's wrong here
Hiding columns does not reduce dataset size.
Common exam traps
The trap here is that candidates often confuse hiding columns (which only affects the user interface) with physically removing them, leading them to choose option D, but only removal before loading reduces dataset size.
Detailed technical explanation
Power BI uses the VertiPaq in-memory columnar storage engine, which compresses and stores every column loaded into the model. Removing unused columns in Power Query Editor prevents them from being imported, directly reducing the memory footprint and improving compression ratios. In real-world scenarios, this is critical when dealing with wide tables from sources like SAP or Salesforce, where hundreds of columns may exist but only a fraction are used in reports.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Prepare the data — This question tests Prepare the data — Read the scenario before looking for a memorised answer..
The correct answer is: Remove the columns in Power Query Editor before loading — Option A is correct because removing columns in Power Query Editor before they are loaded into the data model physically excludes them from the dataset, reducing its size and improving performance. This is the only method that prevents unused columns from consuming memory and storage in the in-memory VertiPaq engine.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This PL-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PL-300 exam.
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