Nandor Kollar
Senior Staff Software Engineer at Cloudera
Munich, Bavaria, Germany
Summary
🤩
Rockstar🎓
Top SchoolNandor Kollar is a Senior Staff Software Engineer based in Munich with a decade of experience building and optimizing backend systems at Cloudera and earlier roles in finance and healthcare. He specializes in data formats and storage, contributing significant fixes and logical-type support to the widely used Apache Parquet Java project and serving as an Avro, Parquet, and Pig committer within the Apache Software Foundation. At Cloudera he progressed through senior engineering ranks, shaping data platform components and mentoring teams across Budapest and Munich. His background includes pragmatic experience in high-reliability environments from Morgan Stanley to GE Healthcare, giving him a strong operational mindset. Colleagues value his combination of deep protocol-level knowledge and hands-on refactoring to improve interoperability and historical timestamp handling. Outside day-to-day work, he quietly influences open-source data tooling by improving metadata conversion and preserving backward compatibility in core libraries.
10 years of coding experience
14 years of employment as a software developer
Master of Computer Applications (MCA) Computer Engineering, Master of Computer Applications (MCA) Computer Engineering at Budapest University of Technology and Economics
Github Skills (5)
parquet10
javas10
back-end-development10
java10
avro9
Programming languages (4)
Github contributions (5)
apache/parquet-java
Nov 2017 - Mar 2026
Apache Parquet Java
Role in this project:
Back-end Developer
Back-end DeveloperContributions:5 reviews, 52 PRs, 17 pushes in 8 years 5 months
Contributions summary:Nandor contributed to the Apache Parquet Java project by implementing support for new logical type representations. They addressed bug fixes, and improved the functionality of the ParquetMetadataConverter. Further contributions included refactoring the modules to leverage the new logical type API, and fixing binary values returned from dictionary encoding. They also worked on improving the consistency of logical type names and on resolving an issue in the handling of timestamps before 1970.
javaparquetapacheparquet-java
nandorKollar/avro
Nov 2016 - May 2025
Mirror of Apache Avro
Contributions:37 pushes, 21 branches in 8 years 7 months
avrojavaapache-avroapache
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