Hello, the developer of db9 here. You’re right, that section is indeed a bit too brief. We will add more architecture documentation later.
What I wanted to convey is that, unlike a standard PostgreSQL, db9 is more like a pg SQL-compatible layer built on top of a large distributed KV store.
I also shared a brief introduction in this tweet, which might help clarify things. https://x.com/dxhuang/status/2032016443114733744