22-25 April 2026

Evolution of User-Defined Functions in Microsoft SQL Server

Proposed session for SQLBits 2026

TL; DR

Explore the evolution of SQL Server UDFs from 2000 to today. Learn key milestones, performance improvements, and best practices for optimizing functions in modern environments.

Session Details

Since their introduction in SQL Server 2000, User-Defined Functions (UDFs) have become a cornerstone for many database developers seeking to encapsulate logic, improve code reusability, and enhance maintainability. This session embarks on a journey through the development and evolution of UDFs in Microsoft SQL Server, highlighting the pivotal updates, performance improvements, and new features introduced with each version.

Attendees will explore the foundational concepts of UDFs in SQL Server, understanding their initial design and limitations. The session will then navigate through subsequent versions, showcasing significant milestones such as inline table-valued functions, scalar UDF inlining, and enhancements in SQL Server 2019 and beyond. We will delve into practical examples, performance considerations, and best practices for optimizing UDFs in the modern SQL Server environment.

3 things you'll get out of this session

- Understand the evolution of user‑defined functions in SQL Server from 2000 to modern versions. - Evaluate key milestones, performance improvements, and limitations of scalar and table‑valued UDFs. - Apply best practices and optimization techniques to improve UDF performance in current SQL Server environments.