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Julien Le Dem

@julien.ledem.net
6K followers 722 following 343 posts

Principal Engineer, Founder, Angel, Advisor, OSS. LFAI&data: OpenLineage, Marquez, ASF: Parquet, Arrow, Iceberg, 🐖 he/him. Me: julien.ledem.net Blog: sympathetic.ink

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Julien Le Dem @julien.ledem.net · 23/09/2026
Fresh off the press: ALP: Adaptive Lossless Floating-Point Encoding in Apache Parquet parquet.apache.org/blog/2026/09... Thank you Kosta Tarasov, @andrewlamb1111.bsky.social, Prateek Gaur
parquet.apache.org
ALP: Adaptive Lossless Floating-Point Encoding in Apache Parquet
A technical overview of ALP's design, performance, and adoption across the Apache Parquet ecosystem.
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Reposted by Julien Le Dem
Gonéri Le Cozannet @goneri76.bsky.social · 29/08/2026
Peut-on s'adapter au changement climatique sans l'atténuer? Bien sûr que non, et à supposer que cela soit possible, s'engager dans une telle voie equivaudrait à se tirer une balle dans le pied Mervi @lefigaro.fr d'avoir publié ma tribune www.lefigaro.fr/vox/societe/...
lefigaro.fr
Gonéri Le Cozannet : «S’adapter au changement climatique sans réduire nos émissions de CO₂ relève de la gageure»
FIGAROVOX/TRIBUNE - La France a renoncé à des politiques climatiques ambitieuses en se laissant convaincre par l’idée, chimérique, d’une adaptation au changement climatique sans tenter de l’atténuer, ...
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The Berkeley Scanner @berkeleyscanner.com · 13/08/2026
A magnitude 3.9 earthquake in Oakland shook Berkeley on Thursday morning, according to early reports.
berkeleyscanner.com
Oakland quake felt in Berkeley
The epicenter was in Oakland but some felt it in Berkeley.
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Julien Le Dem @julien.ledem.net · 13/08/2026
Earthquake!
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Reposted by Julien Le Dem
Adam L @adam-lg.bsky.social · 14/07/2026
Favorite: Parquet Least favorite: XLS(X)
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Julien Le Dem @julien.ledem.net · 26/06/2026
I had a great time seating with Whitney Lee to chat about OpenLineage Datadog Illuminated is such a fun format! www.youtube.com/watch?v=uIuB...
youtube.com
OpenLineage - A Common Observability Framework for Data Pipelines
YouTube video by Datadog Community
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Julien Le Dem @julien.ledem.net · 25/06/2026
The recording of the talk "The Deconstructed Database at Datadog" that Pierre Lacave and I gave at AI Council this year now available. www.youtube.com/watch?v=Bh9O...
youtube.com
The Deconstructed Database at Datadog
YouTube video by AI Council
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Julien Le Dem @julien.ledem.net · 23/06/2026
🌉🛫😴🛬🇫🇷🥖🥐
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Julien Le Dem @julien.ledem.net · 01/06/2026
If you missed my talk "Column storage for the AI era", this is your chance to watch it live tomorrow in SF. thedive.motherduck.com#schedule
thedive.motherduck.com
The Dive — MotherDuck at Snowflake Summit 2026
Your home base during Snowflake Summit.
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Julien Le Dem @julien.ledem.net · 29/05/2026
The recording of my Iceberg Summit keynote "Column Storage for the AI Era" is now available. www.youtube.com/watch?v=qWU3...
youtube.com
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Julien Le Dem @julien.ledem.net · 21/05/2026
Recording of the Seattle Parquet meetup. Thank you Xinli, Micah, Kenny and all the presenters. www.youtube.com/watch?v=69nT...
youtube.com
Seattle Apache Parquet Meetup May 2026
YouTube video by Xinli shang
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Julien Le Dem @julien.ledem.net · 09/05/2026
I’m in this picture and I don’t like it.
Roby: “great McGyver move”“Does a dr mcgyver work here?”“I don’t know”
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Julien Le Dem @julien.ledem.net · 01/05/2026
Last year, I gave a keynote at AI Council about The Deconstructed Database: a composable and extensible database design enabled by the cloud and a collection of standard open source formats and components. (Parquet, Arrow, Substrait, Iceberg, OpenLineage, Calcite, DataFusion).
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Julien Le Dem @julien.ledem.net · 29/04/2026
I'm speaking today at www.openxdata.ai You can watch my talk online.
Column Storage for the AI era
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Julien Le Dem @julien.ledem.net · 26/04/2026
My son is selling his mountain bike. www.pinkbike.com/buysell/4171...
pinkbike.com
2022 YT Capra CF Core 3 Yellow - Large For Sale
2022 YT Capra CF Core 3 Yellow - Large For sale on Pinkbike buysell
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Julien Le Dem @julien.ledem.net · 26/04/2026
Weekend project . Designed and assembled in California.
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Julien Le Dem @julien.ledem.net · 10/04/2026
Thank you for letting me keynote day 2 of the Iceberg summit. I hope you all enjoyed it!
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Julien Le Dem @julien.ledem.net · 10/04/2026
And that’s a wrap! Thank you for a great Iceberg Summit! @thedanicafine.bsky.social, Matt and everyone involved in the organization.
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Julien Le Dem @julien.ledem.net · 19/03/2026
I have LLM jokes, they write themselves.
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Julien Le Dem @julien.ledem.net · 19/03/2026
Paging @dickc
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Julien Le Dem @julien.ledem.net · 05/03/2026
If you want to learn more about the Variant type in Parquet, Aihua Xu and @andrewlamb1111.bsky.social wrote a great blog post on the project blog. parquet.apache.org/blog/2026/02...
parquet.apache.org
Variant Type in Apache Parquet for Semi-Structured Data
Introducing Native Variant Type in Apache Parquet
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Julien Le Dem @julien.ledem.net · 14/02/2026
Great inaugural post about the geospatial types on the Parquet blog. Thank you Jia Yu, Dewey Dunnington , Kristin Cowalcijk, Feng Zhang. More posts coming ! parquet.apache.org/blog/2026/02...
parquet.apache.org
Native Geospatial Types in Apache Parquet
Native Geospatial Types in Apache Parquet
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Julien Le Dem @julien.ledem.net · 13/02/2026
Apache Arrow is ten years old! I can't believe that Apache board meeting when the project was instated was 10 years ago! This went fast! arrow.apache.org/blog/2026/02...
arrow.apache.org
Apache Arrow is 10 years old 🎉
The Apache Arrow project was officially established and had its first git commit on February 5th 2016, and we are therefore enthusiastic to announce its 10-year anniversary! Looking back over these 10...
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Julien Le Dem @julien.ledem.net · 21/01/2026
Congratulations to @andrewlamb1111.bsky.social on becoming the latest Parquet PMC member! Thank you, Andrew, for your leadership in the community. I look forward to our continued collaboration!
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Julien Le Dem @julien.ledem.net · 08/01/2026
File formats! Great references 😎
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Julien Le Dem @julien.ledem.net · 01/01/2026
Happy new year
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Julien Le Dem @julien.ledem.net · 31/12/2025
Bonne année!
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Julien Le Dem @julien.ledem.net · 31/12/2025
And that applies to sparkling wine as well ;)
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Julien Le Dem @julien.ledem.net · 29/12/2025
I always dip the fries in the tartar sauce with my fish and chips.
Pulp fiction quote: in holland they put mayonnaise on French fries. Damn!
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Julien Le Dem @julien.ledem.net · 11/12/2025
In the past few years, we’ve seen a cambrian explosion of new columnar formats, challenging the hegemony of Parquet. Presumably, the design of yore is not going to cut it moving forward. I spent some time to understand a bit better how things actually changed. sympathetic.ink/2025/12/11/C...
sympathetic.ink
Column Storage for the AI Era
In the past few years, we’ve seen a cambrian explosion of new columnar formats, challenging the hegemony of Parquet: Lance, Fastlanes, Nimble, Vortex, AnyBlox, F3 (File Format for the Future). The thi...
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Julien Le Dem @julien.ledem.net · 09/12/2025
If you missed my talk "The advent of the open data lake" at AI By the Bay, the recording is now available. ai.bythebay.io/talks/the-ad... www.youtube.com/watch?v=xHGV...
youtube.com
The advent of the open data lake | Julien Le Dem, AI By the Bay 2025
YouTube video by FunctionalTV
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Julien Le Dem @julien.ledem.net · 08/12/2025
Earthquake!
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Julien Le Dem @julien.ledem.net · 06/12/2025
It turns out that Friday’s NYT’s mini crosswords was written by my 13-year-old.
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Julien Le Dem @julien.ledem.net · 01/12/2025
Parquet praise in the wild :) Nice chatting with you at Datacouncil Hannes! www.youtube.com/watch?v=zeon...
youtube.com
Introducing DuckLake
YouTube video by DuckDB
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Julien Le Dem @julien.ledem.net · 18/11/2025
Come say hi, Wednesday at 10am. I'll be speaking at the AI By the Bay Conference about "The Advent of The Open Data Lake". ai.bythebay.io/talks/the-ad...
ai.bythebay.io
The advent of the open data lake | AI By the Bay
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Julien Le Dem @julien.ledem.net · 14/11/2025
If you missed me giving it live, the slides of my talk, "Column Storage for the AI era" are available here: docs.google.com/presentation...
docs.google.com
Column Storage for the AI era
(illustration hand generated in 1958) “Column Storage for the AI era” © 2025 by Julien Le Dem is licensed under CC BY-NC-SA 4.0. To view a copy of this license, visit https://creativecommons.org/licen...
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Julien Le Dem @julien.ledem.net · 12/11/2025
Netflix: "We capture over a trillion events a day." Datadog: www.datadoghq.com/blog/enginee....
Ted Lasso: "hold my beer"
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Julien Le Dem @julien.ledem.net · 11/11/2025
@openlineage.bsky.social support for Ray by Anyscale www.anyscale.com/blog/announc...
anyscale.com
Anyscale Announces Lineage Tracking for Faster End-to-End Tracing and Debugging of Ray Workloads
Today we are announcing the private beta of Anyscale Lineage Tracking – a new capability that brings end-to-end visibility to distributed AI development for clear pipeline transparency, fast experimen...
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Julien Le Dem @julien.ledem.net · 09/11/2025
Good evening golden gate.
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Julien Le Dem @julien.ledem.net · 07/11/2025
Higher latency but higher throughput on improving the overall data ecosystem.
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Andrew Lamb @andrewlamb1111.bsky.social · 07/11/2025
"if you want to go fast, go alone; If you want to go far, go together" New Apache Parquet Community page is up: parquet.apache.org/community/
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Reposted by Julien Le Dem
Ian Cook @ian.columnar.tech · 29/10/2025
The future of data connectivity is columnar. Today we launched @columnar.tech to accelerate the shift from slow, row-oriented APIs like ODBC and JDBC to >10x faster alternatives powered by @arrow.apache.org. Learn more 👇
columnar.tech
Announcing Columnar
Back to the future of data connectivity
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Julien Le Dem @julien.ledem.net · 03/11/2025
Experimenting with the laser cutter to make 3d objects.
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Julien Le Dem @julien.ledem.net · 31/10/2025
This just went in the oven
Tian provençal before the oven
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Julien Le Dem @julien.ledem.net · 28/10/2025
If you missed my talk: "Data Observability and OpenLineage" at the Datadog summit in SF, here is your chance to catch up on the recording. www.youtube.com/watch?v=uhNo...
youtube.com
Data Observability and OpenLineage
YouTube video by Datadog
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Julien Le Dem @julien.ledem.net · 26/10/2025
Another earthquake
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Julien Le Dem @julien.ledem.net · 25/10/2025
Great time seeing Garbage at the Warfield tonight.
Shirley Manson
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Julien Le Dem @julien.ledem.net · 22/10/2025
I'm speaking tomorrow at "Embracing AI in Open Source" If you've been wondering why we see a flurry of new columnar formats, come see me present "Column Storage for the AI Era" I'll talk about what has changed, new advances in data encoding and how that's pushing Parquet to evolve. luma.com/pxikwty3
luma.com
Next-Gen Data Engineering: Embracing AI in Open Source · Luma
Next-Gen Data Engineering: Embracing AI in Open Source Join us October 23rd at the Silicon Valley AI Hub in Snowflake’s Menlo Park campus for an evening…
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Julien Le Dem @julien.ledem.net · 20/10/2025
Who’s solving the Louvre robbery? Right answers only
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Julien Le Dem @julien.ledem.net · 19/10/2025
First attempt at making prints with the laser cutter. I don’t know what I’m doing but happy to have made something.
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