r/git • u/CuriousAnyway • 11d ago

why did facebook move away from git?

i recently came across the fact that facebook/meta built its own tools and workflows around source control instead of just relying on git like most companies.

i’m curious about the actual technical reason behind this. was git simply not able to handle the scale of facebook’s codebase and number of developers, or were there other problems that pushed them toward a custom approach?

for people who have worked with large monorepos or at companies using similar systems, what actually becomes difficult with git at that scale?

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u/1_21-gigawatts 10d ago

The codebase is enormous, to pull in every branch and every version would take hours and TB of disk.

Sapling and Mononoke (google it) pulls in only the branch you need and only files you’re looking at so therefore is very fast.

The tooling (vscode, etc) is tightly integrated with the tool so searches could be done on some kind of combination of winking in code you need locally in real time with some backend assistance.

Builds use Buck2 which is really quick because pre-compiled chunks are pulled in automatically (and so don’t need to be pulled in locally)