VFSForGit VS git

It's not only Windows that uses Git at Microsoft, but Sharepoint and Office (which includes the on-prem version of SharePoint). In terms of repo size Windows and Office are similar. I was part of the team that migrated Sharepoint from a Perforce clone to Git and helped build the tooling to allow Office to move as well. VFS for Git [1] and Scalar [2] are really good pieces of software.

[1] - https://github.com/microsoft/VFSForGit

[2] - https://github.com/microsoft/scalar

Congratulations! That means you basically figured out how the clone procedure works and found a way to do so just in a partial way (also in an unsafe way). But it is a cool idea, nonetheless.

Also check out the Scalar [1] project and its predecessor, GVFS [2], both from Microsoft to manage their monorepo via a VFS layer.

[1]: https://github.com/microsoft/scalar

[2]: https://github.com/microsoft/VFSForGit

VFS for Git is still Open Source: https://github.com/microsoft/VFSForGit

Microsoft's blog posts have indicated a move to use something as close to off-the-shelf git as possible, though. They say they've stopped using VFS much and are instead more often relying on sparse checkouts. They've upstreamed a lot of patches into git itself, and maintain their own git fork but the fork distance is generally shrinking as those patches upstream.

https://github.com/microsoft/VFSForGit

better than it used to, with the caveat that git in particular is not and has never claimed to be good at versioning blobs.

Oh dear you're not going to like this.

It’s virtualised file system: https://github.com/microsoft/VFSForGit, only downloads what you actually use. Same thing in every large company, but different implementations.

This is where something like VFSForGit[0] helps out. Instead of cloning the entire repo, it creates a virtual file system and fetches objects on demand. MSFT uses it internally for the Windows source tree (which now exceeds 300GB).

[0]: https://github.com/microsoft/VFSForGit

There's also a performance consideration. Not excluding /bin/ or /obj/ folders means dependencies are being tracked as well, and sometimes dependencies themselves are bigger than the program's source code itself. This is commonly the case with node projects, as the node_modules folder can balloon to hundreds of megabytes. They should never be tracked in git due to the nature of how git's internal database works. For e.g. if you delete a dependency because it's no longer needed, you can never fully reclaim that disk space (at least for the master branch) as git will need to keep the binary data stored in its internal tracking database because a previous commit in the master branch has captured the data. As you make more branches, git needs to store the data required to reconstruct your repo to a different state when you switch branches. When a branch has changes measured in the kilobytes, check out is very manageable, but when the differences balloon to many MBs due to the presence of heavy binary files, then checkout between different branches/commits can get very slow. Though, this happens anyway when source code data eventually reaches a certain threshold, beyond the hundreds of megabytes, it's made unnecessarily worse by including any binary files. It's one of the reasons Microsoft created VFS for git: https://github.com/microsoft/VFSForGit.

You mean like VFSforGit? Or the successor for that called Scalar? This has been a solved problem. Microsoft moved their entire Windows codebase to git. There have been a ton of huge improvements to performance as a result of that. And the above two plugins are easily better ways to deal with what you're referring to without resulting to dead tech.

Microsoft had a bunch of solutions to handle their massive Windows repo: VFS for Git (GVFS), Scalar, and now it has a bunch of MS specific patches on top of the official git client, but apparently that one is also not required any more as partial clone is now supported on azure as well (which is another such implementation from Microsoft employees that made it to both GitHub and upstream git).

https://github.blog/2020-01-17-bring-your-monorepo-down-to-s...

https://devblogs.microsoft.com/devops/introducing-scalar/

https://github.com/microsoft/git

https://devblogs.microsoft.com/devops/git-partial-clone-now-...

That was discontinued (like multiple times under different names). And is moved into a git fork. https://github.com/microsoft/git

Interesting! It seems some of Scalar from late 2021 has already made it into the official git project's contrib dir [0]. It looks like Scalar is mostly an opinionated way to configure git [1], especially by using git partial-clone.

Git partial-clone looks almost perfect, except it only downloads and displays files explicitly added to the git sparse-checkout list. I want some "magic" vfs shenanigans that lets me view and browse the full repo exactly as if the full repo where checked out, but when I open a directory or file the contents are downloaded on-demand.

[0]: https://github.com/git/git/tree/master/contrib/scalar

[1]: https://github.com/microsoft/git/blob/vfs-2.37.0/Documentati...

Ironically, Microsoft has been a major contributor to improvements in git for handling large repos after Windows was migrated to git.

https://github.com/microsoft/git

300GB git repo... anyway, good to see there's work for merge in back to git proper, though it seems like that is still a work in progress (maybe) as https://github.com/Microsoft/git/ still seems pretty active.

This is well written and deserves my upvote, because sparse-checkout is part of git and knowing how it works is useful.

That said, there's absolutely no reason to structure your code in a monorepo.

Here's what I think GitHub is doing:

1) Encourage monorepo adoption

2) Build tooling for monorepos

3) Selling tooling to developers stranded in monorepos

Microsoft, which owns GitHub, created the microsoft/git fork linked in the article, and they explain their justification here: https://github.com/microsoft/git#why-is-this-fork-needed

> Well, because Git is a distributed version control system, each Git repository has a copy of all files in the entire history. As large repositories, aka monorepos grow, Git can struggle to manage all that data. As Git commands like status and fetch get slower, developers stop waiting and start switching context. And context switches harm developer productivity.

I believe that Google's brand is so big that it led to this mass cognitive dissonance, which is being exploited by GitHub.

To be clear, here are the two ideas in conflict:

* Git is decentralized and fast, and Google famously doesn't use it.

* Companies want to use "industry standard" tech, and Google is the standard for success.

Now apply those observations to a world where your engineers only use "git".

The result is market demand to misuse git for monorepos, which Microsoft is pouring huge amounts of resources into enabling via GitHub.

It makes great sense that GitHub wants to lean into this. More centralization and being more reliant on GitHub's custom tooling is obviously better for GitHub.

It just so happens that GitHub is building tools to enable monorepos, essentially normalizing their usage.

Then GitHub can sell tools to deal with your enormous monorepo, because your traditional tools will feel slow and worse than GitHub's tools.

In other words, GitHub is propping up the failed monorepo idea as a strategy to get people in the pipeline for things like CodeSpaces: https://github.com/features/codespaces

Because if you have 100 projects and they're all separate, you can do development locally for each and it's fast and sensible. But if all your projects are in one repo, the tools grind to a halt, and suddenly you need to buy a solution that just works to meet your business goals.

VFS for Git was superceded by https://github.com/microsoft/scalar and then many of the features were merged into mainline git, so what is left now is a thin shell around git features in the form of MS's forked git binary: https://github.com/microsoft/git