Zoltán Haindrich
Apache Druid PMC at The Apache Software Foundation
Budapest, Hungary
Summary
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Rockstar🎓
Top SchoolZoltán Haindrich is a backend-focused software engineer with 12+ years building and hardening high-performance analytics and database systems, currently serving as an Apache Druid PMC and long-time committer across Apache Calcite and Hive. He has deep expertise in query optimization, compression, and correctness—demonstrated by substantive fixes and test coverage improvements in major open-source projects such as Apache Druid, Hive, Calcite and TimescaleDB. Zoltán favors simple, flexible designs that make complex systems extensible without sacrificing integrity, a philosophy born from hands-on work across the planner, metastore, and CI reliability. Based in Budapest, he blends algorithmic rigor (algorithms, data structures, parallel algorithms) with practical engineering experience from embedded firmware and real-time vehicle tracking to core database internals. Notably, his contributions include subtle bug fixes in aggregation and expression handling that materially improve production query correctness and stability.
12 years of coding experience
16 years of employment as a software developer
Master’s Degree, Computer Science, Master’s Degree, Computer Science at Eötvös Loránd University
Hungarian, English
Stackoverflow
1,808reputation
185kreached
97answers
8questions
Github Skills (36)
apache-calcite10
unit-testing10
postgresql10
admin10
metastore10
back-end-development10
testing10
compression-algorithm10
databases10
query-optimization10
time-series10
database-administration10
apache-druid10
calc10
java10
Programming languages (12)
Github contributions (5)
apache/hive
Apr 2016 - Oct 2022
Apache Hive
Role in this project:
Back-end Developer
Back-end DeveloperContributions:584 reviews, 417 commits, 407 PRs in 6 years 6 months
Contributions summary:The user, Ashutosh Chauhan, primarily contributed to the Apache Hive codebase, focusing on tasks related to the metastore and JDBC drivers. Their contributions included writing unit tests, fixing bugs, and improving the codebase. The commits reveal a strong understanding of Java programming, data structures, and object-oriented design principles, as evidenced by the various code modifications and bug fixes.
flinksqlapachebig-dataspark
apache/calcite
Apr 2018 - May 2020
Apache Calcite
Role in this project:Back-end Developer
Back-end DeveloperContributions:29 reviews, 35 commits, 65 PRs in 2 years 1 month
Contributions summary:Zoltán primarily contributed to the simplification of logical expressions within the Apache Calcite project. They worked on enhancing the simplification of boolean case statements and improving the logic for NOT-AND-OR expressions. Furthermore, they addressed performance issues and conversion problems related to "IN" expressions, as well as correcting type validation errors and simplifying cast operations. These changes resulted in improved query optimization and correct handling of corner cases within the SQL processing engine.
geospatialapache-calcitesqlapachebig-data
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