PL-300 Model the data Practice Question
You are a data analyst at a healthcare organization. You have a Power BI semantic model with a fact table named Visits that includes a column PatientID and a dimension table named Patients with a column PatientID. The Visits table has 10 million rows, and the Patients table has 500,000 rows. You need to ensure that when users filter the Patients table by patient demographics, the Visits table is filtered accordingly, and that the relationship behaves as expected. What should you do?
⚠ Common exam trap
It's easy for candidates to confuse the direction of the relationship; many candidates mistakenly think the fact table should filter the dimension table.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a one-to-many relationship from Patients[PatientID] to Visits[PatientID] with a single filter direction.
The correct design is a one-to-many relationship from the dimension table to the fact table with a single filter direction. This enforces referential integrity, ensures filters on Patients propagate to Visits, and maintains optimal performance. Reversing the direction or using many-to-many or bidirectional filtering would not meet the requirement and could introduce issues.
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 a one-to-many relationship from Visits[PatientID] to Patients[PatientID] with a single filter direction.
Why it's wrong here
This reverses the natural filter direction. The fact table Visits should not filter the dimension table Patients. If you create the relationship from Visits to Patients, filtering Patients by demographics would not filter Visits; instead, filtering Visits would filter Patients. This is opposite to the required behavior and is not a best practice for a star schema.
- ✓
Create a one-to-many relationship from Patients[PatientID] to Visits[PatientID] with a single filter direction.
Why this is correct
This is correct because the dimension table Patients should filter the fact table Visits. A one-to-many relationship from the dimension to the fact table with a single filter direction is the standard star schema design. It ensures that filters on patient demographics propagate to Visits, and it avoids ambiguity and performance issues associated with bidirectional filtering.
- ✗
Create a one-to-many relationship from Patients[PatientID] to Visits[PatientID] with a bidirectional filter direction.
Why it's wrong here
While a bidirectional relationship would allow filters to propagate both ways, it introduces ambiguity and performance overhead. In a simple star schema with one fact and one dimension, bidirectional filtering is unnecessary and can cause unexpected results when multiple relationships exist. The single filter direction from dimension to fact is sufficient and recommended.
- ✗
Create a many-to-many relationship between Patients[PatientID] and Visits[PatientID] with a single filter direction.
Why it's wrong here
Many-to-many relationships are used when both tables have duplicate values on the key, which is not the case here. Patients[PatientID] should be unique, and Visits[PatientID] can have duplicates. Using many-to-many would not enforce referential integrity and could lead to incorrect results and poor performance. It is not the appropriate relationship type for this scenario.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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.