IT'S FINALLY COMPLETE! (35% OFF)

Just submitted the last bits to complete my latest book with Manning.

As always, thanks for your support over the years. It really does mean a lot, and it has been quite the ride!

Find this and all my other books at https://books.alexmerced.com

#ApacheIceberg #DataLakehouse #DataEngineering

This is interesting. In my blogposts analyzing ATproto I had compared the shared heap vs message passing from a CS perspective

https://dustycloud.org/blog/how-decentralized-is-bluesky/
https://dustycloud.org/blog/re-re-bluesky-decentralization/

Ian Preston of Peergos did the actual formal mathematical proof of the incentive structure: https://peergos.net/secret/z59vuwzfFDp45jmsA6Wj2jc9hemCjB4JJHB81iosJsA9GAVRtkbrqBs/1024927538#%7B%22app%22:%22markup%22%2c%22path%22:%22ianopolous/docs%22%2c%22args%22:%7B%22filename%22:%22social-scaling.note%22%7D%2c%22writable%22:false%2c%22secretLink%22:true%2c%22linkpassword%22:%22UfAQURKSTTmM%22%2c%22open%22:true%7D

> It is interesting that this is independent of N. Let's say you have 1000 servers, and 1000 followers per user. Then the shared heap model uses about the same network bandwidth. With a small number of servers SH can be better, with many servers AP is better.

> The conclusion is that the shared-heap model builds in a structural incentive to keep M small, and thus has a natural centralizing force. Conversely there is an incentive in AP to keep F small.

Ie, there is a mathematical incentive in ATproto to only have a few large players.

Many new people asking what Mastodon and the Fediverse actually are, and how servers connect to each other. I've tried to do a simple non-technical guide about this:

➡️ https://fedi.tips/what-is-mastodon-what-is-the-fediverse

TL:DR - The phone network lets you choose a provider and call people on other providers. Mastodon and the wider Fediverse do this for social networks.

If you prefer videos, these are useful:

"What is Mastodon?"
https://fedi.video/w/cbQE3NRw76FayQCSdb14TU

"Introducing the Fediverse"
https://videos.elenarossini.com/w/64VuNCccZNrP4u9MfgbhkN

#FediTips

Today is the new semester for @CMUDB's Intro to Database Systems! We're going harder into material than ever before. Projects are more challenging but you can use LLMs to help. We also have 10min talks each Wed from leading DB companies. Follow from home/prison on YouTube: https://15445.courses.cs.cmu.edu/fall2025

Everything is available for free to non-CMU students:
• Lectures on YouTube: https://www.youtube.com/playlist?list=PLSE8ODhjZXjYMAgsGH-GtY5rJYZ6zjsd5
• Slides + Notes + Homeworks on course website.
• Project source code on GitHub: https://github.com/cmu-db/bustub
• Grading with Gradescope (see FAQ ➡️ https://15445.courses.cs.cmu.edu/fall2025/faq.html#q7)

Special thank you to our Affiliate companies for their support this academic year:
• ClickHouse
• DataStax
• dbt Labs
• Firebolt
• MotherDuck
• RelationalAI
• SingleStore
• SpiralDB
• PingCAP / TiDB
• Yellowbrick
• Yugabyte

Monday Sept 22nd is the start of @CMUDB latest seminar series: Future Data Systems
We are hosting speakers from leading systems in the data lake / lakehouse space.

Mondays @ 4:30pm ET via Zoom. Open to the public. Videos posted to YouTube: https://db.cs.cmu.edu/seminars/fall2025/

🗓️ Schedule:
Sep 22: Apache Iceberg
Sep 29: Apache Hudi
Oct 06: MotherDuck DuckLake
Oct 13: SpiralDB's Vortex
Oct 27: SingleStore
Nov 03: Delta Lake
Nov 10: Mooncake
Nov 17: Firebolt
Nov 24: XTDB
Dec 01: Apache Polaris