Git VS git-filter-repo

Boy, I can't find this either (but also, the kernel mailing list is _really_ difficult to search). I really remember Linus saying something like "it's not a real SCM, but maybe someone could build one on top of it someday" or something like that, but I cannot figure out how to find that.

You _can_ see, though, that in his first README, he refers to what he's building as not a "real SCM":

https://github.com/git/git/commit/e83c5163316f89bfbde7d9ab23...

Here is the direct link, as HN somehow removes the query string: https://github.com/git/git/commits?author=peff&since=2023-10...

I understand all that.

I'm saying, if you write a survey and one of the possible answers is "diff", but you don't clearly define what you mean by "diff", then don't be surprised if respondents use any reasonable definition that makes sense to them. Ask an ambiguous question, get a mishmash of answers.

The thing that Git uses for packfiles is called a "delta" by Git, but it's also reasonable to call it a "diff". After all, Git's delta algorithm is "greatly inspired by parts of LibXDiff from Davide Libenzi"[1]. Not LibXDelta but LibXDiff.

Yes, how Git stores blobs (using deltas) is orthogonal to how Git uses blobs. But while that orthogonality is useful for reasoning about Git, it's not wrong to think of a commit as the totality of what Git does, including that optimization. (Some people, when learning Git, stumble over the way it's described as storing full copies, think it's wasteful. For them to wrap their heads around Git, they have to understand that the optimization exists. Which makes sense because Git probably wouldn't be practical if it lacked that optimization.)

The reason I'm bringing all this up is, if you're trying to explain Git, which is what the original article is about, then it's very important to keep in mind that someone who is learning Git needs to know what you mean when you say "diff". Most people who already know Git would tend to gravitate toward the definition of "diff" that you're assuming (the thing that Git computes on the fly and never stores), but people who already know Git aren't the target audience when you're teaching Git.

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[1] https://github.com/git/git/blob/master/diff-delta.c

Didn't Git have a new default merge strategy, `ort` https://github.com/git/git/blob/master/Documentation/RelNote... ?

Yes, but you are referring to standalone scripts, not functions defined within a Bash script.

Compare for example the following helper code used for git command completion inside Bash and inside PowerShell.

Bash: https://github.com/git/git/blob/master/contrib/completion/gi...

**WARNING**: git-filter-branch has a glut of gotchas generating mangled history rewrites. Hit Ctrl-C before proceeding to abort, then use an alternative filtering tool such as 'git filter-repo' (https://github.com/newren/git-filter-repo/) instead. See the filter-branch manual page for more details; to squelch this warning, set FILTER_BRANCH_SQUELCH_WARNING=1. Proceeding with filter-branch... Rewrite a3a48b09e282854c80bf4ad02a017e249e161fd8 (2/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 6e788e83a338e45b348d93d682b32c816ee2fbff (3/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 7a378a0145bce70bea213ca5f9062138544db5f2 (4/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 0637c9659623644cfceb35be10f2a1fe5c468e04 (5/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 6c421eb99adc6b987cff7f3cada31e9313638072 (6/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 98001e5b97270efa4a8ab5bd0452be56dd76883d (7/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Rewrite 2ca4e161a4af2b8f38c46faf848fdbb3e550f23c (8/8) (0 seconds passed, remaining 0 predicted) rm 'config.js' Ref 'refs/heads/secret_keys' was rewritten.

Yup you need https://github.com/newren/git-filter-repo Take a look at https://github.com/newren/git-filter-repo/blob/main/INSTALL.md for instructions

git filter-repo: a third-party command actually, as a replacement to Git's own filter-branch, that allows rewriting the whole history of a repository to remove a mistakenly added file, or help extract part of the repository to another.

I needed to archive some old repositories into a monorepo and of course I gave myself the requirement of maintaining git history, in some way. I tried a couple of solutions but it wasn't until I stumbled upon the git-filter-repo project at https://github.com/newren/git-filter-repo and another article which I've since lost (which was badly documented anyway) that I was able to figure out how to do this.

Git objects are not designed to be changed, they are immutable blobs. This is not a problem if you are making a reader, but is a problem when you want to change things, tools like old git-filter-branch or the newer filter repo abstract all reference updating away for you

Make sure your gitignore is setup right (GitHub has a repo of good defaults). If you messed that up, you could rewrite git history to remove the big stuff. Use git-filter-repo. Not sure how that works for LFS.

git-filter-repo

Check out git filter repo https://github.com/newren/git-filter-repo

I personally prefer git-bfg ( https://rtyley.github.io/bfg-repo-cleaner/ ) ... though git-filter-repo ( https://github.com/newren/git-filter-repo ) is quite popular. The difference for me was that git-bfg is JVM based and my work machine has Java on it while git-filter-repo is python based... and my work machine is without python.