22-25 April 2026 
User Data Functions: Development, Testing, and Integration
Proposed session for SQLBits 2026TL; DR
Learn when and why to use User Data Functions (UDF) in Fabric and the best practices for developing and testing them. In addition, you’ll see a live demo of testing UDFs locally before publishing.
Session Details
User Data Functions (UDFs) enable extending capabilities with custom Python logic hosted in Microsoft Fabric. When should you consider using one? What is the best way to develop, test, and debug the solution? How to install custom libraries? What options do we have for triggering the execution? I will answer all of these questions during this session.
I will also demonstrate how to run and debug a UDF locally before publishing it to Microsoft Fabric. In addition, I will show how to trigger a UDF with a REST API call and from a Power BI report, as well as various ways to use existing data in a semantic model and/or new data as input for the UDF.
This talk is intended for data architects, developers, and analysts. Join this session to learn when to use UDFs and how to develop your solution using an optimal approach. I will also list the recommended tools and libraries required for those just getting started.
I will also demonstrate how to run and debug a UDF locally before publishing it to Microsoft Fabric. In addition, I will show how to trigger a UDF with a REST API call and from a Power BI report, as well as various ways to use existing data in a semantic model and/or new data as input for the UDF.
This talk is intended for data architects, developers, and analysts. Join this session to learn when to use UDFs and how to develop your solution using an optimal approach. I will also list the recommended tools and libraries required for those just getting started.
3 things you'll get out of this session
- Understand when and why to use UDFs
- Learn best practices for development and testing
- Live demonstration of how to use the pytest framework to properly test your solution