Jiajun
Denver, Colorado, United States
Summary
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RockstarJiajun Sun is a software engineer in Mountain View with seven years of experience building ML and AI systems, currently working on applied machine learning at ByteDance after contributing to AWS SageMaker. He blends a strong research background (Stanford MS, 3.9) and applied computer vision/data science experience from Blue River and earlier research roles with production engineering skills demonstrated at AWS. An Apache Calcite committer, he has deep back-end SQL expertise—implementing functions like APPROX_COUNT_DISTINCT, CHAR, and dynamic LIMIT/OFFSET handling—and has improved dialect compatibility across major engines. Comfortable moving between low-level data systems and higher-level ML services, he focuses on LLM/AGI work while maintaining a pragmatic track record of shipping robust, standards-aware code.
7 years of coding experience
Github Skills (5)
apache-calcite10
javas10
sql10
java10
big-data8
Programming languages (4)
Github contributions (5)
apache/calcite
Nov 2021 - Nov 2022
Apache Calcite
Role in this project:
Back-end Developer
Back-end DeveloperContributions:371 reviews, 21 commits, 112 PRs in 1 year
Contributions summary:Jiajun primarily contributed to the core logic of the Apache Calcite project, focusing on enhancing the SQL dialect support. Their work involved implementing the `APPROX_COUNT_DISTINCT` function for various SQL dialects and fixing issues related to view expansion. Furthermore, the user added support for handling dynamic parameters in `LIMIT` and `OFFSET` clauses and corrected the handling of parentheses in `UNION` queries. They also made updates related to the serialization and deserialization of the `Snapshot` operator, and added the implementation for the `CHAR` function for MySQL and Spark SQL dialects.
apache-calcitegeospatialcalcitejavabig-data
JiajunBernoulli/calcite
Jun 2021 - Mar 2026
Contributions:2 reviews, 35 PRs, 205 pushes in 4 years 9 months
accumuloapache-calciteapachebig-datadatastream
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