Aljoscha Krettek
Member Of Technical Staff at Materialize
Germany
Summary
🤩
Rockstar🎓
Top SchoolAljoscha Krettek is a seasoned software engineer with 12 years' experience building and hardening distributed stream-processing systems, currently a Member of Technical Staff at Materialize. A co-founder of Ververica and long-time committer and PMC member for Apache Flink and Apache Beam, he blends product-minded engineering with deep open-source stewardship. His work spans backend systems, SQL engine internals, and test automation—evident from contributions that improved Flink’s robustness, Beam’s runner integrations, and Materialize’s SQL parser and string functions. Having moved from academic research at TU Berlin and internships at IBM Almaden to startup leadership in Berlin, he pairs rigorous CS foundations with practical performance and correctness fixes. Notably, he contributes to both code and project infrastructure (including Flink website content and test harness refactors), showing a rare mix of developer, maintainer, and documentation focus.
13 years of coding experience
12 years of employment as a software developer
Bachelor of Science (BS) Computer Science, Bachelor of Science (BS) Computer Science at DHBW StuttgartMaster of Science (MS) Computer Science, Master of Science (MS) Computer Science at Technische Universität Berlin
English, German, French
Github Skills (42)
self-organization10
documentation10
database10
markdown10
content-management-system10
postgresql10
apache-flink10
back-end-development10
evaluation10
expressions10
testing10
databases10
flink-sql10
java10
refactor10
Programming languages (16)
Github contributions (5)
apache/flink-web
Apr 2016 - Feb 2020
Apache Flink Website
Role in this project:
Technical Writer
Technical WriterContributions:33 commits, 15 PRs, 2 pushes in 3 years 10 months
Contributions summary:Aljoscha's contributions primarily revolve around website content updates for the Apache Flink project. Their commits include restructuring the community menu, adding links to Flink Improvement Proposals (FLIPs), and updating the documentation to reflect the latest stable releases. The user also regenerates the website and makes modifications to the blog, including allowing for multiple authors per post. Their work focuses on enhancing the website's information and accessibility for the user.
apache-flinkscalajavabig-dataflink
apache/flink
May 2014 - Feb 2021
Apache Flink
Role in this project:Back-end Developer & Test Automation Engineer
Back-end Developer & Test Automation EngineerContributions:324 reviews, 1397 commits, 889 PRs in 6 years 10 months
Contributions summary:Aljoscha's commits focus on refactoring and testing aspects of the Apache Flink project. They refactored and improved test harnesses, which implies a focus on test-driven development and test code maintainability. Their work is concentrated on ensuring the robustness and reliability of specific components, as evidenced by the renaming of methods, adding more specific sink API tests, and fixing bugs in existing test setups. The contributions suggest involvement in both back-end development and quality assurance.
apache-flinkscalajavabig-dataflink
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