Stamatis Zampetakis
Paris, Ile-de-France
Summary
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RockstarStamatis Zampetakis is a Senior Staff Software Engineer based in Paris with seven years of professional experience and a research doctorate in computer science focused on scalable RDF data management and query optimization on cloud/Hadoop. He combines academic depth with hands-on backend engineering at Cloudera and as an active Apache contributor and Calcite PMC leader. His open-source work spans Apache Calcite, Hive and Avatica — implementing structured-type access in the Enumerable runtime, fixing critical Hive NullPointerExceptions, optimizing reduce-sink deduplication and reducer counts, and modernizing Avatica’s tests and infrastructure. Known for turning complex query semantics into maintainable runtime code and thorough unit tests, he blends performance tuning, test automation and long-term project stewardship. An interesting detail: he has repeatedly translated distributed query optimization research into pragmatic fixes and performance wins in widely used Apache projects.
8 years of coding experience
Github Skills (23)
apache-calcite10
junit510
testing10
big-data10
calc10
java10
javas10
junit10
performance-optimization10
sql10
junit310
junit410
relational-algebra10
test-automation10
debug9
Programming languages (9)
Github contributions (5)
apache/calcite-avatica
Jan 2019 - Dec 2022
Apache Calcite Avatica
Role in this project:
Back-end Developer & Test Automation Engineer
Back-end Developer & Test Automation EngineerContributions:38 reviews, 11 commits, 33 PRs in 4 years
Contributions summary:Stamatis focused on improving the Avatica project by addressing bugs, enhancing testing infrastructure, and refactoring code. They implemented parameterized unit tests for struct accessors, improving data type handling. The user also updated the testing framework by replacing legacy assertion utilities with more modern Hamcrest matchers, increasing maintainability. Furthermore, the user contributed to streamlining the project by removing obsolete JavaScript files and updating dependencies.
geospatialapache-calcitesqlapachebig-data
apache/calcite
Aug 2018 - Jan 2023
Apache Calcite
Role in this project:Back-end Developer
Back-end DeveloperContributions:341 reviews, 125 commits, 304 PRs in 4 years 6 months
Contributions summary:Stamatis implemented structured-type access within the Enumerable runtime, eliminating the DOT operator and translating field access expressions into calls to the `SqlFunctions.structAccess` method. They also added a new test schema and unit tests with queries to access fields of struct types. Furthermore, the user contributed to adding a variant of `FilterProjectTransposeRule` that could push down a Filter containing correlated variables, while addressing an issue with Windows. This work involved modifying existing code and creating tests to validate the changes.
geospatialapache-calcitesqlapachebig-data
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