The correct answer is to split the column by delimiter in Power Query, using the space character to separate 'FullName' into 'FirstName' and 'LastName'. This is the most efficient method because Power Query performs the split at the query level using M language, which is optimized for data transformation and refreshable in the data model, whereas DAX calculated columns are computed in the storage engine and can degrade report performance. On the PL-300 exam, this scenario tests your understanding of when to use Power Query transformations versus DAX—a common trap is choosing a DAX calculated column for simple splits, which adds unnecessary overhead. Remember the memory tip: "Split in Query, not in DAX" to keep your model lean and fast.
PL-300 Model the data Practice Question
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.
You are modeling data from a source that includes a column 'FullName' (e.g., 'John Doe'). You want to create separate 'FirstName' and 'LastName' columns for analysis. What is the most efficient way?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
In Power Query, split the column by delimiter (space) into two columns.
Option D is correct because splitting a column by delimiter in Power Query is the most efficient, native method for transforming data at the query level. It leverages Power Query's M language to perform the split in a single step, which is optimized for performance and can be refreshed automatically. This approach avoids the overhead of DAX calculated columns, which are computed in the storage engine and can slow down report rendering.
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.
✗
Create calculated columns using DAX functions LEFT, RIGHT, and FIND.
Why it's wrong here
DAX calculated columns are less efficient than Power Query transformations.
✗
Use the 'Replace Values' feature to manually separate names.
Why it's wrong here
Manual replacement is not efficient for many rows.
✗
Use Excel formulas in a source query.
Why it's wrong here
Not applicable in Power Query.
✓
In Power Query, split the column by delimiter (space) into two columns.
Why this is correct
Power Query provides a built-in split function.
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 choose DAX calculated columns (Option A) because they are familiar with Excel-like formulas, but they overlook that Power Query is the correct tool for data transformation in Power BI, and DAX should be reserved for measures and calculated columns that depend on the data model's context.
Detailed technical explanation
How to think about this question
Under the hood, Power Query's 'Split Column by Delimiter' uses the M function `Table.SplitColumn`, which operates on the entire column in a single pass, leveraging the query folding engine to push the transformation back to the data source when possible. A subtle behavior is that splitting by space will create two columns even if the name contains multiple spaces (e.g., 'John Michael Doe'), which may require additional steps like splitting by the rightmost space or using a custom delimiter. In a real-world scenario, this is critical when dealing with inconsistent name formats, such as 'Dr. Jane Smith' or 'John Doe Jr.', where a simple space split would produce three columns instead of two.
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: In Power Query, split the column by delimiter (space) into two columns. — Option D is correct because splitting a column by delimiter in Power Query is the most efficient, native method for transforming data at the query level. It leverages Power Query's M language to perform the split in a single step, which is optimized for performance and can be refreshed automatically. This approach avoids the overhead of DAX calculated columns, which are computed in the storage engine and can slow down report rendering.
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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