I have created a diagram for Flarum's database (for all ~200 extensions of FreeFlarum) via DBDiagram. It is basically a graph for all the tables, columns and relationships.
Link: https://dbdiagram.io/embed/622b142361d06e6eade4171b
As PNG:
Extensions are equal to FreeFlarum (as of 11th March, 2022). I tried to arrange it as best as I could so it doesn't become an absolute spaghetti (it kind of did anyways)... I made it mostly for my own project(s), but I thought of sharing it with the community so it may be useful to everyone (e. g.: this can be used to speed up the creation of Flarum migration scripts).
Note: There's also https://drawsql.app/templates/flarum, but it seems outdated and doesn't contain any extensions. Maybe someone will update it in the future
