Power BI Interview Questions with Answers Part-4 ✅

31. Explain the role of gateways in Power BI. 
Gateways connect on-premises data sources to Power BI Service securely, enabling scheduled data refresh without moving data to the cloud.

32. How do you schedule data refresh in Power BI? 
In the Power BI Service, configure refresh frequency (daily/weekly), time, and credentials to automate dataset updates, using gateways if on-premises sources are involved.

33. What is Row-Level Security (RLS) in Power BI? 
RLS restricts data access for users based on roles by filtering rows dynamically, ensuring users see only data relevant to them.

34. How do you implement RLS in Power BI? 
Define roles and DAX filters in Power BI Desktop’s Modeling tab, then assign users to these roles in Power BI Service.

35. What are Power BI apps? 
Apps are packaged collections of dashboards, reports, and datasets distributed to wider audiences for easier consumption and governance.

36. What are dataflows in Power BI? 
Dataflows allow ETL (extract, transform, load) processes to be created in the cloud, reusing data preparation logic across multiple datasets.

37. How do you use parameters in Power BI? 
Parameters enable dynamic input values for queries or data transformations, making reports more flexible (e.g., changing data source or filter values).

38. What are custom visuals in Power BI? 
User-developed or marketplace visuals that extend standard Power BI visuals with specialized charts and unique features.

39. How do you import custom visuals into Power BI? 
Download visual (.pbiviz) files or add from AppSource marketplace directly inside Power BI Desktop or Service.

40. Explain performance optimization techniques in Power BI. 
Use star schema modeling, prefer measures over calculated columns, limit visuals per page, optimize data queries, enable query reduction, and apply aggregations.

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