ClickHouse comes to Seoul: Dev Korea #4 Recap
On November 18, Dev Korea returned with its fifth community event, this time with ClickHouse, bringing together 140+ attendees for a deep dive into modern analytics infrastructure, performance-driven systems, and practical lessons from teams building with data at scale.
With a packed venue and standing room only, it was one of our largest Dev Korea events so far and a strong signal of how fast the international tech community in Seoul continues to grow.
⚡ High-performance analytics, built for scale
The evening focused on ClickHouse, the open-source, column-oriented database designed for fast analytics on massive datasets. The evening kicked off with a solid introduction to ClickHouse for those encountering it for the first time.
Ken Lee and Derek Chia from ClickHouse walked the audience through the core architecture of ClickHouse, explaining what makes it fundamentally different from traditional databases in the big data and analytics space.
They covered:
- how ClickHouse is designed for analytical workloads
- its column-oriented architecture and distributed scalability
- why query performance remains fast even at large scale
Derek also shared some of his favorite ClickHouse features, from horizontal scaling to performance-focused design choices, and showed how these can simplify and speed up real-world analytics workflows.
🔍 A journey of using ClickHouse to optimize ClickHouse
In a more advanced and thought-provoking session, Antoine Grondin from Humanlog explored what happens when you use ClickHouse to observe and optimize ClickHouse itself.
The talk took a self-referential approach to database optimization, showing how internal observability tables can be built to track:
- compression behavior
- query performance
- schema evolution over time
All of this data lives inside the same ClickHouse instance being analyzed.
It was a practical and slightly mind-bending look at how deeply teams can instrument their systems when performance truly matters.
🤖 Reflections on the Horangi leaderboard and Korean LLM evaluation
The final talk shifted the focus toward AI and large language models.
Hyunwoo Oh from Weights & Biases shared lessons from operating the Horangi Leaderboard, the largest and most widely used Korean LLM evaluation leaderboard, over the past year.
He walked through:
- challenges of evaluating Korean language models at scale
- insights gained from running real-world benchmarks
- learnings from recent version upgrades and evaluation changes
The session gave attendees a rare behind-the-scenes look at how LLM evaluation works in practice, especially in the Korean ecosystem where language nuance matters deeply.
🎁 ClickHouse swag and audience Q&A rewards
After the talks, we moved into community updates and open Q&A.
Questions came quickly, and participation was high. To reward curiosity:
- ClickHouse stickers were available for everyone
- ClickHouse T-shirts were given to attendees who asked questions
It created a fun and interactive atmosphere and encouraged even more people to jump into the discussion.
🍔 Burgers and hallway conversations
The night wrapped up with cheeseburgers and chicken burgers from CryCheeseBurger, which were a big hit with the crowd.
As always, the real magic happened during networking:
- conversations about systems, startups, and side projects
- engineers exchanging notes on tooling and architecture
- newcomers meeting people for the first time
- familiar faces reconnecting
No flashy setup, just good food, honest conversations, and a room full of builders.
🙌 Huge thanks
This event would not have been possible without:
- ClickHouse for supporting the event and bringing great content and swag
- Our speakers: Ken Lee, Derek Chia, Antoine Grondin and Hyunwoo Oh who shared real insights instead of marketing slides
- All the volunteers who helped make this event a success: Aaron McCollum, Alena Kazakova, Charles Chang, Denizay Dönder who made everything flow seamlessly from start to finish
- All 140+ attendees who filled the venue and brought energy into the room
Seeing the venue completely full was incredibly motivating for us as organizers.
👀 What’s next
Dev Korea keeps growing, and this event made it clear that there is strong demand for practical, technical, community-driven meetups in Seoul.
We are already preparing upcoming events with global tech companies and local builders.
👉 Check out upcoming events at https://dev-korea.com/events
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Here’s to more nights of learning, building, and meaningful community in Seoul. 🍻✨
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