The correct approach is to filter rows in Power Query before import, specifically by applying a row-level filter on the CustomerAddress table to keep only rows where IsPrimary equals True, then merging with the Customer dimension. This is the best practice because it leverages Power Query’s native filtering capabilities to reduce data volume at the source, ensuring only necessary rows are loaded into the model and avoiding complex DAX or relationship overhead. On the Microsoft Power BI Data Analyst PL-300 exam, this scenario tests your understanding of query folding and data shaping—a common trap is trying to handle the filter with a DAX measure or a bidirectional relationship, which adds runtime cost and model complexity. Remember the memory tip: “Filter early, merge cleanly”—always push row-level filters upstream in Power Query to keep your model lean and your measures simple.
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 designing a Power BI model that includes a fact table with sales data and a dimension table for customers. Each customer can have multiple addresses, but you only need the primary address for analysis. The source system has a 'CustomerAddress' table with a 'IsPrimary' flag. What is the best approach to bring this into the model?
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.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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, filter the CustomerAddress table to only include rows where IsPrimary = True, then merge with Customer.
Option C is correct because it uses Power Query to filter the CustomerAddress table to only primary addresses before merging with the Customer dimension. This ensures that only the necessary rows are imported into the model, reducing data volume and avoiding complex DAX or relationship overhead. The result is a clean, single-row-per-customer dimension that directly supports analysis without runtime filtering.
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 a DAX measure to filter the address table dynamically.
Why it's wrong here
Measures don't handle row-level filtering for dimension attributes.
✗
Import the entire CustomerAddress table and create an active relationship on the CustomerID column.
Why it's wrong here
This imports unnecessary data and may cause ambiguity if multiple addresses.
✓
In Power Query, filter the CustomerAddress table to only include rows where IsPrimary = True, then merge with Customer.
Why this is correct
This loads only the needed rows, reducing model size.
Clue confirmation
The clue words "best", "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a calculated table using SUMMARIZE to get the primary address per customer.
Why it's wrong here
SUMMARIZE can be performance-intensive and is not needed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose Option B, thinking that importing the full table and using a relationship is simpler, but they overlook the need to enforce a single primary address per customer, which requires additional filtering logic that complicates the model and degrades performance.
Detailed technical explanation
How to think about this question
Under the hood, Power Query's filter and merge operations are performed in the M language during data refresh, which pushes the filtering logic to the source database (if query folding is supported), minimizing data transfer. In contrast, a DAX calculated table using SUMMARIZE is evaluated in the VertiPaq engine after data is loaded, which can consume more memory and processing time. A real-world scenario where this matters is when the CustomerAddress table contains millions of rows; filtering in Power Query with query folding to SQL Server (e.g., WHERE IsPrimary = 1) drastically reduces import time and model size.
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.
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, filter the CustomerAddress table to only include rows where IsPrimary = True, then merge with Customer. — Option C is correct because it uses Power Query to filter the CustomerAddress table to only primary addresses before merging with the Customer dimension. This ensures that only the necessary rows are imported into the model, reducing data volume and avoiding complex DAX or relationship overhead. The result is a clean, single-row-per-customer dimension that directly supports analysis without runtime filtering.
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.
Are there clue words in this question I should notice?
Yes — watch for: "best", "primary". 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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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