Forschungsgebiete

• Umbra: A Flash‑Based Database System with In-Memory Performance
• Efficient Query Processing
• Efficient Factorization in Relational Database Systems

Publikationen & Auszeichnungen

The Data World Is Not Flat: Efficient Factorized Execution for Relational Systems
Lehner Stefan, Thomas Neumann
VLDB 2026

What Works and What Does Not: A Winning Strategy for Join Query Execution
Team SortMergeJoins
SIGMOD Programming Contest 2025 — First Place

Efficient Index Structures for Range Joins in Relational Database Systems
Stefan Lehner
Master's Thesis, TU München, 2022 (Supervisor: Thomas Neumann, Advisor: Maximilian Reif)

Deep Reinforcement Learning and Evolutionary Computation for Combinatorial Optimization
Stefan Lehner
Bachelor's Thesis, TU München, 2020 (Supervisor: Daniel Cremers, Advisor: Vladimir Golkov)

Lehre

Winter 2022/2023:	Grundlagen: Datenbanken
Summer 2023:	Systems Programming in C++ Seminar - Modern Database Systems
Winter 2023/2024:	Grundlagen: Datenbanken
Summer 2024:	Datenbanksysteme und moderne CPU-Architekturen
Winter 2024/2025:	Grundlagen: Datenbanken
Summer 2025:	Datenbanksysteme und moderne CPU-Architekturen
Winter 2025/2026:	Grundlagen: Datenbanken
Summer 2025:	Datenbanksysteme und moderne CPU-Architekturen
Winter 2026/2027:	Grundlagen: Datenbanken

Tools

• Exam Monitor