Jan Steemann
Senior Software Engineer at MongoDB
Cologne, North Rhine-Westphalia, Germany
Summary
🤩
Rockstar🎓
Top SchoolJan Steemann is a Senior Software Engineer with 14 years of deep backend and database engineering experience, now at MongoDB after a decade-plus driving core development at ArangoDB. He specializes in multi-model database internals, query execution and storage engine optimizations, with hands-on work such as LZ4 compression for in-memory caches and RocksDB-related improvements. Jan is a pragmatic test automation and reliability advocate, having strengthened ArangoJS and MongoDB test suites and fixed subtle, non-deterministic issues in driver and core tests. His open-source contributions span high-profile projects (ArangoDB, MongoDB, RocksDB), reflecting both low-level performance tweaks and higher-level API/feature correctness. Based in Cologne, he combines an economics background with deep systems craftsmanship, which often surfaces as a focus on measurable performance and maintainability rather than flashy features. Colleagues describe him as the kind of engineer who quietly hardens systems so they scale and survive real-world workloads.
14 years of coding experience
23 years of employment as a software developer
Diplom-Ökonom Economics, Diplom-Ökonom Economics at University of Bremen
English, Spanish, German
Stackoverflow
46reputation
601reached
1answer
0questions
Github Skills (30)
code-optimization10
storage-engine10
javascript10
c-language10
testing10
rocksdb10
databases10
aql10
database-testing10
mongodb-database10
aggregation-framework10
mochajs10
driver10
performance-optimization10
nodejs10
Programming languages (15)
Github contributions (5)
arangodb/arangodb
Mar 2012 - Jan 2023
🥑 ArangoDB is a native multi-model database with flexible data models for documents, graphs, and key-values. Build high performance applications using a convenient SQL-like query language or JavaScript extensions.
Role in this project:
Back-end Developer & Database Engineer
Back-end Developer & Database EngineerContributions:5511 reviews, 21834 commits, 9458 PRs in 11 years
Contributions summary:Jan primarily contributed to the optimization and enhancement of ArangoDB's in-memory cache, specifically focusing on edge indexes and collection and document caching. This included implementing LZ4 compression to reduce memory footprint and improve performance. Furthermore, the user worked on improving the performance of AQL queries by leveraging various index types for filter and sort conditions and introduced a new REST API to query the available key generators. These changes involved code related to the RocksDB storage engine and AQL query execution.
data-modelsdatabase-modelextensionsjavascriptquery-language
facebook/rocksdb
Sep 2015 - Nov 2022
A library that provides an embeddable, persistent key-value store for fast storage.
Role in this project:Back-end Developer
Back-end DeveloperContributions:17 reviews, 41 commits, 61 PRs in 7 years 3 months
Contributions summary:Jan primarily focused on improving the RocksDB codebase through various refactoring and optimization efforts. Their contributions include fixing typos, enhancing code formatting, and addressing potential memory leaks within the arena allocation mechanisms. Furthermore, the user made several modifications to improve the efficiency of the code, such as passing strings by const reference and removing unused variables. They also fixed bugs and improved the structure of the codebase in multiple files.
persistent-storagebigtablefast-storagelsm-treedatabase
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