02/02/2025
Top 15 Advanced Power BI Interview Questions & Answers
🔥 Power BI experts, here are the answers to yesterday’s questions! 🔥
1️⃣ Row-Level Security (RLS):
RLS restricts data access at the user level by defining security roles in Power BI Desktop and assigning them in Power BI Service. It uses DAX expressions in role filters.
2️⃣ Calculated Tables:
Calculated tables are created using DAX expressions and are useful when you need a new table derived from existing data, like aggregated summaries or filtered datasets.
3️⃣ Storage Modes (Import, DirectQuery, Live Connection):
Import: Best for performance; loads data into Power BI.
DirectQuery: Connects to a live database but may impact performance.
Live Connection: Similar to DirectQuery but works with SSAS models.
4️⃣ Optimizing Performance:
Reduce visual complexity.
Use aggregations and summarizations.
Optimize DAX calculations.
Enable query reduction features.
5️⃣ DAX & Complex Calculation Example:
DAX (Data Analysis Expressions) is used for calculations. Example:
TotalSales = SUMX(Sales, Sales[Quantity] * Sales[Price])
This calculates total sales dynamically.
6️⃣ Power Query & Data Cleansing:
Power Query is used for ETL (Extract, Transform, Load). Common techniques:
Removing duplicates
Handling missing values
Splitting and merging columns
7️⃣ Power BI Data Model & Relationships:
Relationships connect tables via keys, enabling seamless data integration for accurate reporting.
8️⃣ Custom Visuals & Extensions:
Use Power BI Custom Visual SDK to build custom visuals when default visuals don’t meet business needs. Example: A custom KPI visualization.
9️⃣ Power BI Gateway:
Allows on-premise data to sync with the Power BI Service. Essential for scheduled data refreshes.
🔟 Power BI Desktop vs. Service vs. Mobile:
Desktop: Used for report creation.
Service: For sharing & collaboration.
Mobile: For on-the-go access.
1️⃣1️⃣ Incremental Refresh:
Loads only new data instead of the full dataset, improving performance in large datasets.
1️⃣2️⃣ Dynamic Security Roles:
Uses USERPRINCIPALNAME() in DAX to assign row-level security dynamically based on user login.
1️⃣3️⃣ Paginated Reports:
Used for print-ready, table-heavy reports with precise formatting needs.
1️⃣4️⃣ Drill-Through:
Allows users to navigate from a summary view to detailed insights. Configure it by setting up a drill-through page with filters.
1️⃣5️⃣ Power BI Integration with Azure & SharePoint:
Connect Power BI to Azure Data Lake Storage for big data analysis or SharePoint for team collaboration.
💡 Want more Power BI tips? Drop a comment below! ⬇️