PL-300 Prepare the data Practice Question
You are preparing data for a Power BI report at a hospital network. You connect to an Azure Synapse Analytics dedicated SQL pool. The fact table contains encounter records, and a dimension table named Patients stores protected health information. Hospital policy requires that the Patients table be filtered to only active patients before it is loaded into the semantic model, and the filter must be applied as close to the source as possible to minimize data transfer. You also need to be able to refresh the model without modifying the source database. What should you do in Power Query?
⚠ Common exam trap
The trap here is assuming that any filter placed early in the query is automatically folded, when in fact a preceding non-foldable step can break folding and force the filter to run locally.
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
✓
In the Patients query, add a step that filters the IsActive column to true, and ensure this step is folded by keeping only foldable transformations before it.
Filtering the IsActive column inside Power Query is a foldable transformation for Azure Synapse Analytics, so the row restriction is pushed down into the source query. This minimizes data transfer and avoids modifying the database. The other options either filter after import, require source changes, or apply filtering at the wrong layer.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
In the Patients query, add a step that filters the IsActive column to true, and ensure this step is folded by keeping only foldable transformations before it.
Why this is correct
Filtering on the IsActive column is a foldable operation for Azure Synapse Analytics, so Power Query can translate it into a WHERE clause in the native query sent to the source. This reduces the rows transferred over the network and satisfies the requirement to filter as close to the source as possible. No source schema change is needed.
- ✗
Import the entire Patients table and apply a visual-level filter on IsActive in the report so only active patients appear.
Why it's wrong here
A visual-level filter only affects what is displayed in that visual; all patient rows are still imported into the semantic model. This increases data transfer and model size, and it does not enforce the policy at the data layer. Sensitive rows for inactive patients would still reside in the dataset, which violates the stated requirement.
- ✗
Create a stored procedure in Azure Synapse Analytics that returns only active patients, and call it from Power Query.
Why it's wrong here
Creating a stored procedure requires modifying the source database, which the scenario explicitly prohibits. While a stored procedure can restrict rows at the source, the constraint of not altering the database rules it out. Filtering in Power Query achieves the same reduction without any DDL changes.
- ✗
Use a DAX calculated table in the semantic model that uses FILTER to keep only rows where IsActive is true.
Why it's wrong here
A DAX calculated table is computed after data has already been imported, so all patient rows would still be transferred from Azure Synapse Analytics. This does not reduce network traffic and does not filter close to the source. It also adds processing overhead in the model rather than in the query.
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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.