Bio
I am a software architect, open source leader and entrepreneur who loves collaborating with others in Open Source projects. I started the Parquet project in collaboration with the Impala team at Cloudera back when I was at Twitter. I chaired the project for many years at the Apache foundation and Parquet is now the de-facto standard for data lakes. I later contributed to the creation of the Arrow project as a founding engineer at Dremio. Before that I received my initiation contributing to OpenSource in the Apache Pig project where I evolved from contributor to committer to PMC member and eventually chaired the project in 2013. More recently I started the OpenLineage project while being the CTO and co-founder of Datakin which was later acquired by Astronomer. OpenLineage came out of Marquez, the project we co-created at Wework on the data platform team.
I blog at Sympathetic.Ink
Projects
- Apache Parquet: co-creator, PMC chair
- Apache Arrow: co-creator and PMC member
- Apache Pig: PMC member, PMC chair 2013
- Apache Iceberg: PMC member
- OpenLineage: creator and project lead at the LFAI&Data foundation
- Marquez: co-creator, former project lead at the LFAI&Data
- Brenus: a java bytecode generation library
Podcasts
- It Depends: Celebrating 10 years of Apache Parquet with Julien Le Dem and Nong Li; Ep. 34 April 2023
- DC_THURS: Data Lineage w/ Julien Le Dem (Datakin)
- Data Driven NYC: Data Observability and Pipelines: OpenLineage and Marquez
- Data engineering podcast
- The Analytics Engineering Roundup: Ep 10: Why Data Lineage Matters w/ Julien Le Dem of OpenLineage
- Software Engineering daily
Presentations
Over the years I gave a number of talks. You’ll find them in chronological order on the presentations page. You’ll also find a playlist of talks recordings on Youtube. Here is a selection by theme.
Nurturing Open Source communities
- Data Council 2024: Ten+ years of building open source standards.
- Airflow Summit 2023: Nurturing an Open Source Community is Like Tending a Garden video
Open Data Lineage: OpenLineage, Marquez
- Data and AI summit 2023: Cross-Platform Data Lineage with OpenLineage
- Berlin Buzzwords 2022: Cross-Platform Data Lineage with OpenLineage
- Data and AI Summit May 2021: Data lineage and observability with OpenLineage
- Data Driven January 2021: Data pipelines observability with OpenLineage and Marquez
- Subsurface 2020: Data Lineage and observability with Marquez
- OpenCore Summit: Observability for data pipelines with Open Lineage
Data Architecture
- AI Council May 12, 2026: The Deconstructed Database at Datadog slides
- Data Council (keynote) Apr 22, 2025: The Deconstructed Database and The advent of the open data lake video slides
- IEEE Infrastructure 2020: Data Platform Architecture Principles
- Data Eng Conf April 2018: From flat file to deconstructed database, The evolution and future of the Big Data ecosystem.
Columnar formats: Parquet, Arrow
- Iceberg Summit (keynote) Apr 8, 2026: Column Storage for the AI era video slides
- Data Works Summit 2018: The columnar roadmap, Apache Parquet and Apache Arrow
- Strata NY 2017: The columnar roadmap, Apache Parquet and Apache Arrow Video
- Spark Summit 2017: Improving Python and Spark Performance and Interoperability with Apache Arrow video
- Data Eng Conf NY November 2016: The future of column-oriented data processing with Arrow and Parquet video
- Strata 2015: How to use Parquet as a basis for ETL and analytics
- HPTS 2015: If you have your own Columnar format, stop now and use Parquet
- Efficient Data Storage for Analytics with Apache Parquet 2.0
- Hadoop Summit 2013: Parquet, Columnar storage for the people
Embedding Pig in scripting languages
- Pig meetup: Embedding Pig in scripting languages
