10+ Senior Power BI Developer Interview Questions and Answers

Optimizing slow-performing Power BI reports requires various strategies.

• Identify and remove unnecessary visuals or data

• Optimize DAX calculations and queries

• Reduce the number of visuals on a single page

• Use aggregations and summary tables for large datasets

• Consider using DirectQuery mode for real-time data

• Use query folding to push data transformation operations to the data source

The question involves finding the output of a table, ways to find max and second max in SQL, row level security on column, and index in details.

• To find the output of the table, you need to analyze the pattern of the data and count the occurrences of each value for each letter.

• To find the max and second max in SQL, you can use the MAX() function with ORDER BY and LIMIT clauses, or use a subquery to find the second highest value.

• Row level security on a column can be implemented...read more

RLS restricts data access based on user roles, ensuring users only see relevant data.

• RLS filters data based on user's role or attributes

• It limits access to rows in a table based on user's role

• Users can only see data that they have permission to access

Data governance in Power BI involves establishing policies, processes, and controls to ensure data quality, security, and compliance.

• Establish data quality standards and guidelines for data sources

• Implement role-based access control to restrict access to sensitive data

• Monitor data usage and track changes to ensure compliance with regulations

• Create data lineage documentation to track the flow of data from source to report

Star schema has a single fact table connected to multiple dimension tables, while snowflake schema has normalized dimension tables.

• Star schema denormalizes data for faster query performance.

• Snowflake schema normalizes data to reduce redundancy and improve data integrity.

• Star schema is easier to understand and query, but snowflake schema is more flexible and scalable.

• Example: A star schema for a sales database would have a fact table for sales transactions connected to dimensi...read more

Direct query connects to data source in real-time, while import loads data into Power BI for faster analysis.

• Direct query retrieves data from source on-demand, ensuring real-time data accuracy.

• Import loads data into Power BI for faster analysis, but may not reflect real-time changes.

• Direct query is suitable for large datasets that require up-to-date information.

• Import is ideal for smaller datasets or when real-time data is not necessary.

Best practices for data modelling

• Understand the business requirements before designing the data model

• Normalize data to reduce redundancy and improve data integrity

• Use surrogate keys for better performance and scalability

• Avoid complex relationships and keep the model simple and easy to understand

• Regularly review and optimize the data model for efficiency

Business Intelligence tools help in analyzing and visualizing data to make informed decisions.

• Power BI

• Tableau

• QlikView

• MicroStrategy

• SAP BusinessObjects

Power BI is a business analytics tool by Microsoft that provides interactive visualizations and business intelligence capabilities.

• Power BI is a business analytics tool by Microsoft

• It allows users to create interactive visualizations and reports

• Users can connect to various data sources to gather insights

• Power BI offers a wide range of data visualization options such as charts, graphs, and maps