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20 Power BI Interview Questions Every Professional Should Know

When preparing for your next business intelligence or data analytics role, mastering Power BI interview questions is not something that needs to be neglected. When you are at the jr to mid level of your career, most hiring managers are looking for more than just a base understanding of DAX and dashboards. Manager really wanted to see you understanding data modeling, security and performance optimization, then apply that to real-world business problems.

In this post we will cover 20 Power BI questions that I or a hiring manager has used to interview qualified candidates. Whether you’re moving up the analytics ladder or transitioning from Excel to enterprise BI, these questions can give you a competitive edge.

This sample is part of a series that shows how you can use Power BI intervie questions with business-oriented data, reports, and dashboards

1. What are the main components of Power BI?

Answer: Power BI is made up of several core components:

  • Power BI Desktop: Windows application for data modeling, visualization, and report building.
  • Power BI Service: Cloud-based platform for sharing, publishing, and collaborating on reports.
  • Power BI Mobile: Mobile app for viewing dashboards on the go.
  • Power BI Gateway: Facilitates secure data transfer between on-premises data sources and the cloud service.
  • Power BI Report Server: On-premises report server for hosting Power BI reports internally.

2. Explain the difference between a dashboard and a report in Power BI.

Answer:

  • A report is a multi-page canvas with multiple visuals based on one dataset.
  • A dashboard is a single-page summary view made up of visuals pinned from one or more reports or datasets.

3. What is DAX, and why is it important in Power BI?

Answer: DAX (Data Analysis Expressions) is a formula language used in Power BI for calculated columns, measures, and custom tables. It allows you to:

  • Perform dynamic calculations
  • Filter data contextually
  • Create advanced KPIs and aggregations
    DAX is central to answering complex Power BI interview questions that test real analytical thinking.

4. What is the difference between calculated columns and measures?

Answer:

  • Calculated columns are evaluated row by row and stored in the data model, increasing model size.
  • Measures are calculated at query time based on filter context, making them more efficient and better for performance.

5. How do you optimize Power BI reports for performance?

Answer:

  • Use star schema over snowflake
  • Avoid unnecessary calculated columns
  • Minimize the number of visuals on a report page
  • Limit use of slicers and filters
  • Use aggregations, composite models, and incremental refresh
    Performance-based Power BI interview questions are common for senior-level candidates.

6. What are relationships in Power BI, and what types are there?

Answer: Power BI supports:

  • One-to-many (default)
  • Many-to-one
  • Many-to-many (limited support)
  • Inactive relationships (can be activated using USERELATIONSHIP in DAX)

7. How do you implement row-level security (RLS) in Power BI?

Answer:

  • Define roles and DAX filters in Power BI Desktop
  • Publish to Power BI Service
  • Assign users to roles in the Service
    RLS ensures users see only the data they’re authorized to view, which is crucial for data governance.

8. Can Power BI connect to real-time data sources?

Answer: Yes. Power BI supports:

  • DirectQuery
  • Live Connection (e.g., to SSAS)
  • Push Datasets using REST API or Power Automate
    Real-time data is essential in executive dashboards and operational analytics.

9. What are some limitations of DirectQuery in Power BI?

Answer:

  • Slower performance due to constant query execution
  • Limited support for complex DAX functions
  • Some visuals and transformations are restricted
    These limitations often surface in Power BI interview questions when evaluating trade-offs between import and DirectQuery modes.

10. How does Power BI handle data refresh?

Answer:

  • Scheduled refresh (for imported data)
  • On-demand refresh via Power BI Service or REST API
  • Incremental refresh for large datasets (Pro or Premium required)
    Power BI Gateway is required for on-prem data sources.

11. What is a star schema, and why is it recommended?

Answer: A star schema has one fact table surrounded by dimension tables. It is preferred because:

  • It simplifies DAX calculations
  • Improves performance
  • Makes data modeling intuitive
    Expect modeling-based Power BI interview questions to emphasize star vs snowflake schema.

12. What are bookmarks in Power BI?

Answer:
Bookmarks allow you to save the current state of a report page including filters, visuals, and selections. They are used in:

  • Interactive storytelling
  • Report navigation
  • Custom drill-through experiences

13. How do you troubleshoot performance issues in Power BI?

Answer:

  • Use Performance Analyzer in Power BI Desktop
  • Review Query Diagnostics
  • Check model size and cardinality
  • Optimize DAX logic
  • Minimize visuals and cross-filtering complexity

14. What’s the difference between Power BI Pro and Power BI Premium?

Answer:

  • Pro: License per user. Supports sharing and collaboration.
  • Premium: Dedicated capacity, larger model size, AI features, paginated reports, and no per-user limits.

15. What are composite models?

Answer:
Composite models allow you to combine Import and DirectQuery sources in one model. This gives flexibility in performance and data freshness.

16. What are the advantages of using Power Query over DAX for transformations?

Answer:

  • Power Query (M language) is used for data shaping and transformation before load
  • DAX is used after load, mainly for aggregations and metrics
    Best practice is to do as much as possible in Power Query to reduce complexity and improve performance.

17. What is the role of Power BI Gateway?

Answer:
It acts as a bridge between on-premises data sources and the Power BI Service. There are two types:

  • Personal Gateway (for individuals)
  • Enterprise Gateway (for multiple users and scheduled refreshes)

18. How do you ensure data quality in Power BI reports?

Answer:

  • Perform checks in Power Query
  • Use DAX to flag anomalies or nulls
  • Create validation dashboards
  • Implement data source certifications and auditing
    Expect governance-related Power BI interview questions to dig into this.

19. What is drillthrough in Power BI?

Answer:
Drillthrough allows users to navigate to a report page filtered to a specific context (e.g., customer, region). It enhances data exploration and is often used alongside tooltips and bookmarks.

20. How do you manage version control and collaboration in Power BI?

Answer:

  • Use Power BI Deployment Pipelines (Premium)
  • Integrate with Azure DevOps for source control
  • Use shared workspaces and standard naming conventions
    This topic often appears in Power BI interview questions for teams working in enterprise environments.

Final Thoughts

When you are heading into an interview, make it a priority to review these Power BI interview questions until the answers feel natural. These questions are just a starting point for your studies. Make sure you are writing DAX from scratch and get comfortable with basic data modeling principles. If you are able to apply these answers and data modeling principles to real use cases, it will set you apart from the competition. The hiring manager want to know what you know but also how you think.

Whether you’re moving into an analyst role or stepping into BI role, mastering these Power BI interview questions can make the difference between a good interview and an offer.

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