The answer is that the source must be a relational database like SQL Server, the transformations must be natively supported by the database engine, and the query must be structured so that Power Query can translate it into a single SQL statement. This is correct because query folding in Power Query relies on the ability to push data-shaping steps—such as a WHERE clause filter on a date column—back to the source as a native query; if any transformation, like a custom column or unsupported date calculation, cannot be expressed in SQL, folding breaks and the operation runs locally, losing performance benefits. On the PL-300 exam, this tests your understanding of when Power Query can leverage source-side processing, often appearing as a scenario where a filter seems simple but a preceding step (e.g., a merged column) prevents folding—a common trap is assuming all filters fold automatically. Remember the mnemonic: RNT—Relational source, Native support, and Translateable steps.
PL-300 Prepare the data Practice Question
This PL-300 practice question tests your understanding of prepare the data. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 preparing data from a SQL Server database. The query includes a WHERE clause that filters rows based on a date column. You want to ensure that the filter is pushed back to the database (Query Folding). Which THREE conditions must be met?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The transformations applied must be supported for query folding.
Option A is correct because query folding in Power Query requires that all transformations applied to the source data are natively supported by the source database engine. If a transformation (e.g., certain date calculations or custom columns) cannot be translated into a SQL statement, Power Query will break folding and perform the operation locally, negating the performance benefit.
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.
✓
The transformations applied must be supported for query folding.
Why this is correct
Not all transformations support folding.
Related concept
Read the scenario before looking for a memorised answer.
✗
All columns from the table must be loaded to the data model.
Why it's wrong here
Not required for folding.
✗
The query must use a DirectQuery connection.
Why it's wrong here
Folding works with Import mode as well.
✓
The query must not combine data from multiple sources.
Why this is correct
Mashups prevent folding.
Related concept
Read the scenario before looking for a memorised answer.
✓
The source must be a relational database like SQL Server.
Why this is correct
Query folding is supported for relational sources.
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 assume DirectQuery is required for query folding, but folding works in both Import and DirectQuery modes as long as the source and transformations support it.
Detailed technical explanation
How to think about this question
Query folding relies on the Power Query M engine translating transformations into native SQL statements (e.g., SELECT, WHERE, JOIN) that the source database executes. For SQL Server, this means the M expression must map to T-SQL constructs; unsupported operations like certain date functions or custom M functions force local evaluation. In real-world scenarios, a filter on a date column using a native SQL function like CAST or DATEADD will fold, but a custom M function like Date.AddDays may not, depending on the connector.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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: The transformations applied must be supported for query folding. — Option A is correct because query folding in Power Query requires that all transformations applied to the source data are natively supported by the source database engine. If a transformation (e.g., certain date calculations or custom columns) cannot be translated into a SQL statement, Power Query will break folding and perform the operation locally, negating the performance benefit.
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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