Lorenz is an Algorithm Engineer for Big Data, algorithms researcher, and experienced high-performance modern C++ programmer. He works as a Software Engineer on Firebolt's Query Processing team, building the cloud data warehouse of the future. Before that, he completed his PhD thesis at KIT. His research focuses on probabilistic distributed algorithms for Big Data problems.

Professional Experience

Software Engineer — Firebolt Analytics

Since September 2021

Working on the vectorised query engine of Firebolt’s cloud data warehouse, including feature development, performance optimisation, and stability.


PostDoc in Algorithm Engineering — KIT

December 2020 – September 2021

Focus: static approximate membership query & retrieval (perfect hash static function) data structures. Designed and implemented BuRR (bumped ribbon retrieval), a retrieval and static approximate membership query (AMQ) data structure with sub-1% space overhead and query times on the order of a single cache miss.

Other Responsibilities included supervising BSc and MSc thesis projects and course work, coordinating a high-performance computing (HPC) project, and leading seminars and exercises.


Doctoral Researcher — KIT

December 2014 – November 2020, Algorithm Engineering Group

Focus: Parallel & Distributed Algorithms for Big Data Problems

Thesis: Communication-Efficient Probabilistic Algorithms: Selection, Sampling, and Checking, Advisor: Peter Sanders

Designed, analysed, and implemented probabilistic run-time correctness verification for fundamental operations (aggregations, sorting, …) in Thrill, an Apache Spark-like research prototype [1]

Presented the first parallel algorithm for constructing alias tables, a popular data structure for sampling from discrete distributions and an open problem for decades; the first algorithm that requires time linear in the output size for sampling with replacement from discrete distributions [2]

Developed communication-efficient algorithms for various selection problems, bulk priority queues, and (weighted) reservoir sampling [3], [4]

A full list of my publications is available on my Google Scholar page

Other Responsibilities included supervising BSc and MSc thesis projects and course work, coordinating a high- performance computing (HPC) project, and leading seminars and exercises


Maintainer — Glowing Bear

Since 2013

Developer and Maintainer of Glowing Bear, a web-based IRC frontend using WebSockets

Previous Experience

Undergraduate Teaching Assistant — KIT

2010/2011 & 2012/2013

Tutoring students and correction of weekly assignments of the lectures “Algorithmen 1” and “Programmierparadigmen”.


MSc in Computer Science — University of Leicester

Graduated with Distinction

Thesis: “Compression Methods for Labelled Trees”, Advisor: Rajeev Raman.


BSc in Computer Science — KIT

Thesis: “Speed–Consumption Trade-Off for Electric Vehicle Routing”, Advisor: Dorothea Wagner.