Hi there 👋

I’m Jan — a software engineer and computer scientist (Dr. rer. nat.) working on database internals, mostly PostgreSQL. My research background is in spatial and spatio-temporal data management — storing and querying spatial and multi-dimensional data at scale. I’m based in Hamburg, Germany, and have over 25 years of industry experience.

Today I work on PostgreSQL internals at PlanetScale, both on internal projects and on community work. Before that I worked on database internals at Nile and Timescale, and in academia on distributed databases, where I published several papers. On this blog I write about database internals, profiling (perf, flame graphs, eBPF), and query optimization.

📫 Contact: jnidzwetzki@gmx.de
🔗 LinkedIn - GitHub - Google Scholar
⚡ Fun fact: the first Linux distribution I ever installed was SuSE 6.1 (Kernel 2.2.6), in 1999. My first computer had a 100 MHz Pentium 1 and 16 MB RAM and otherwise ran Windows 95.

Projects

Open-source tools I have built or maintain. See the portfolio for the full list and screenshots.

PostgreSQL tooling

pg_lock_tracer — A collection of tools to trace PostgreSQL lock internals (heavyweight locks, LWLocks, row-level locks) using eBPF.
pg_plan_alternatives — Show every alternative plan considered by the PostgreSQL optimizer during planning, using eBPF to instrument the optimizer.
Query Plan Explorer — Visualize PostgreSQL query plan flips and plan stability across different parameter values.
postgresql-sandbox — Install and manage many PostgreSQL versions side by side, each with its own build flags (release, debug, sanitizer), for testing.
pg-dev-container — A VS Code dev container that gives you a debug build of PostgreSQL and all the tooling to develop or debug PostgreSQL or extensions — ready to run in seconds.

Research databases

SECONDO — I maintain the kernel of this extensible DBMS for spatial and spatio-temporal data, developed at the FernUniversität in Hagen.
BBoxDB — A distributed key-bounding-box-value store for multi-dimensional data (e.g., spatial and spatio-temporal data), built from scratch as my PhD project. BBoxDB Streams adds continuous range queries and spatial joins over data streams.
Distributed SECONDO — A distributed version of SECONDO on top of Apache Cassandra, built for my master’s thesis.

Curriculum Vitae

2026–present — Software Engineer, PlanetScale — PostgreSQL internals (internal and community work).
2024–2026 — Founding Engineer, Nile — a tenant-aware, storage/compute-decoupled and distributed version of PostgreSQL. My work focused on decoupling compute from storage by streaming and decoding WAL, tenant-aware query routing across compute nodes, and planner changes to keep per-tenant queries efficient on shared tables.
2022–2024 — Software Engineer, Timescale — a time-series extension for PostgreSQL. My contributions focused on planner improvements, custom scan nodes, join pushdown support for the multi-node version, faster continuous aggregates, and the first SIMD-accelerated vectorized functions.
2014–2022 — Dr. rer. nat. in Computer Science, FernUniversität in Hagen (part-time) — thesis on distributed databases, awarded best PhD thesis of the year by the Faculty of Mathematics and Computer Science. Created BBoxDB and Distributed SECONDO, and contributed to the SECONDO extensible database system.
2009–2014 — B.Sc. & M.Sc. Computer Science, FernUniversität in Hagen (part-time) — focus on operating systems and distributed and cooperative systems; master’s thesis recognized by Springer as one of the best of the year.
Earlier — Staatlich geprüfter Informatiker (DAA Technical College, 2006–2009, completed while working full-time) and an apprenticeship as IT Specialist for System Integration (2002–2005). Earlier roles spanned system administration, network administration, software development, and a CTO position.

For more detail, see my LinkedIn profile.

Interests

Database systems and operating systems
Software architecture — especially distributed, scalable, and fault-tolerant systems
Performance optimization, profiling, and benchmarking
Economics, financial markets, and algorithmic trading systems

Selected Publications and Talks

A full list is on Google Scholar or DBLP.

Talks

Profiling PostgreSQL: perf, Flame Graphs, and eBPF Tools in Practice - PostgreSQL Conference Germany 2026 / Slides
Handling Time-Series Data in a Relational DBMS: Challenges and Solutions - Keynote at GvDB 2024

Publications

Large Language Models, Agents, and the MCP in Database Development - Datenbank-Spektrum 2026
Unfair by design: eBPF-based scheduling of mixed database workloads - Pre-print on arxiv.org (co-author)
BBoxDB Streams: Scalable Processing of Multi-Dimensional Data Streams - Distributed and Parallel Databases 2022
Distributed Arrays: An Algebra for Generic Distributed Query Processing - Distributed and Parallel Databases 2021 (co-author)
BBoxDB Streams: Distributed Processing of Real-World Streams of Position Data - EDBT 2021 / Slides
BBoxDB: A Distributed and Highly Available Key-Bounding-Box-Value Store - Distributed and Parallel Databases 2020
Demo Paper: Large-Scale Spatial Data Processing With User-Defined Filters in BBoxDB - IEEE Big Spatial Data 2019 / Poster / Slides — won the IEEE Best Demo and Short Paper Award
BBoxDB - A Scalable Data Store for Multi-Dimensional Big Data - CIKM 2018 / Poster
Distributed SECONDO: An Extensible and Scalable Database Management System - Distributed and Parallel Databases 2017
Distributed SECONDO: A Highly Available and Scalable System for Spatial Data Processing - SSTD 2015 / Poster
Optimierte Speicherzuteilung an Operatoren in Datenbanksystemen (Optimized Memory Allocation to Operators in Database Systems) - Informatiktage 2013 / Poster

Theses

BBoxDB: A Distributed Key-Bounding-Box-Value Store - My PhD Thesis
Distributed SECONDO - A Distributed DBMS Based on SECONDO and Apache Cassandra - My Master Thesis
Operator Cost Models for Progress Estimation and Optimization in Database Systems - My Bachelor Thesis

GPG Key

Jan Nidzwetzki <jnidzwetzki@gmx.de>
Fingerprint: A8FA E105 7812 65C5 7A53 58C9 918E 92F4 0507 962E

Public key block

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                          ( Hello )
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