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Edit here at the top to clarify: I’m talking about rebasing your own commits before pushing. It sounded like the parent comment was talking about blanket use of rebase. I don’t advocate rebasing other people’s pushed commits, other than a few very exceptional circumstances.

> What is really wrong with having a graph that actually reflects the real history of changes as they were made at them time?

You’re inflicting irrelevant noise and cognitive load on yourself and other people. Noise in the history can also cause all kinds of trouble with merges and with bisect and other git features. A clean history is easier to work with.

Given that Linus advocates rebasing to clean the repo history, I’m curious where the whole “we must preserve the real history”, and dogmatic belief that messy history is some sort of “correct” git design/philosophy.

There is no “real” history. Commit order is arbitrary, especially between orthogonal changes by different people. Anything you modify later using rebase can (and is) done before rebase. There is no sacred set of events to preserve, and it has real and practical ramifications to let the repo get messy when you’re on a large team.

Why not embrace the idea of preserving the semantic history, the intent, as cleanly and clearly as possible, rather than focus on preserving arbitrary noise that doesn’t mean anything to you, let alone others?

> I’ve given up arguing with colleagues that it’s possible to have a branch & merge work-flow without constant re-basing.

It is possible, but it’s not desirable.

> Allowing the history graph to be manipulated and changes seems to have become part of the most popular git work-flows even though it’s a recipe for serious pain in a distributed VCS.

Would you elaborate on what pain you’re talking about? Rebasing is something that happens before push to master, if you’re using it properly, and that’s what the article here is talking about. If anyone’s rebasing the remote’s branches, that is bad, but that is not common practice.

Aside from that, you’re talking about git design and failing to acknowledge that rebase and manipulating the graph history is the design of git. Updating local history is a good thing, and it was designed that way intentionally.

I completely agree that rebase and manipulating the graph history is part of the design of git. But also you can use git effectively without manipulating the history (in a non-incremental way). And you don't lose anything in terms of branching and merging - in fact you gain in terms of safety and simplicity in a distributed system.

The argument I guess is about what you consider the cost of inflicting "irrelevant noise and cognitive load" on other users. I believe it's not significant and is mostly a function of the deficiencies of the history browsing tooling. On the other hand, I believe that the cost of making rewriting history part of the workflow is significant in terms of the load it places on users to learn features like rerere, for example.

If I've understood you correctly then I think neither of us can be right or wrong - it depends what each of us considers a greater "cognitive load" or cost which is going to be based on our personal experiences and preferences rather than something empirical.

It’s still not clear what you’re talking about exactly, will you clarify? Perhaps some concrete examples of the safety and simplicity gains you’re referring to?

Are you saying, and arguing with your team, that individuals should always branch and merge, even when they want to check in single commits, or small numbers of commits?

I don’t consider what happens before push to be “history” at all. Do you? I do consider what happens after push to be history, and for pushed commits, I agree, people should not rebase them.

Branching was designed for the isolation and safety of multi-person teams working on features that take non-trivial amounts of time. Arguing over what individuals should do when not working in teams in a branch is possibly a bit of bike-shedding. I don’t know if that’s what we’re doing here, but on the other hand there are some clues: rebasing is something people do to their own private branch before push, but not normally to other people’s commits after they’ve pushed.

I do think it’s noisy and unnecessary to have two commits for every single-commit change in master. A lot of teams specifically disallow that practice and require direct checkins to master for single commit changes, just to prevent the noise.

If you’re advocating never using rebase, and never rewriting your own history before you push, then I think that is a dogmatic approach that misunderstands the goals and tools in git and fundamentally mistakes git’s philosophy.

If you’re saying that people are rebasing your changes after you pushed them, then I agree with you completely.

I’m not calling anyone wrong. But this isn’t a disagreement over which way has cognitive load. You asked what was wrong with noisy history, and I answered. Your example of having to learn rerere only applies to the team lead, the person doing the merges, and it only comes up once in a while. Not everyone needs to learn rerere, and nobody needs to use it all the time. My example, noisy history, applies to everyone on the team at all times. On my teams, I prefer that people learn git well, and keep their histories clean.

Bit late to reply but regarding the advantages of not allowing rebase operations in a distributed system: if you can only change the version tree by adding nodes to leaves and by adding attributes to nodes (e.g. for merge arrows, tags, etc.), then combining distributed changed versions of a version tree is relatively trivial and users need never fear pushing and pulling.

Or more formally, there is a partial order on version trees (inclusion) and if all changes to version tree are monotonic with respect to this partial order, then it will always be possible to combine distributed versions without conflict.

An analogy might be that I prefer storing raw facts in databases, where practical and performing aggregations/filtering/etc. as queries during retrieval rather than storing filtered and aggregated data.

Typical rebase operations like squashing commits or removing merge history destroy information. Rather than decide up front what information is interesting, why not keep it and provide better tooling for filtering and aggregating commit information?

And what I'm suggesting here isn't radical - other VCSs offer branching and merging without requiring operations similar to rebase. Git itself supports such a workflow and many tutorials introduce git with a simple workflow that does not involve rebasing. I've used such systems in the past and because they had decent version browsing tooling, there was very little "noisy history" overhead. If you wanted a linear view of a branch like "master", you could view the history that way; if you wanted to drill into the branches, sub-branches and merges involved in a particular "master" version, you could do that also.

So yes, you are talking about individual branching & merging in order to commit a single change. And you are talking about never using the rebase command. Why? What are the tangible benefits to never using rebase on your own private commits? You didn’t give me any concrete examples. This seems exceedingly academic and it also seems like you’re either not understanding normal git workflow, or are trying to work in an ad for Pijul or something?

If you use git like I’ve proposed - which is how most people actually use it - by calling commits “history” only after they’ve been shared with someone else, e.g. pushed, then you get all the same guarantees that you are proposing, and the workflow is one of adding only leaves.

Rebase is something you usually do locally before adding nodes to the shared tree, and really has no bearing on published history, nor does it affect published history or change the order or monotonicity of shared events, because you never rebase already published commits. It is not only possible to use rebase in a non-destructive way, it is the most common workflow, and you’re arguing against that part in favor of something that offers zero advantages.

It’s not possible to never have a merge conflict. It is possible to do better than git, but if two people change the same file in the same location, you have a problem, no matter how many monotonic partial orderings you have.

> other VCSs offer branching and merging without requiring operations similar to rebase

Git does not require rebase for branching and merging, and you already know this because you’re advocating single commits in master from individuals get branched and then merged instead of rebased locally. Lots of tutorials don’t mention rebase because it’s irrelevant in the context, and because rebase isn’t required.

Be specific: what systems exactly are you talking about using in the past that had no rebasing and better tooling? There’s no discussion here without concrete examples.

To get the best of both worlds: You could use normal merges while working on a branch, and then when it's done do one rebase (which also removes merge commits) before merging back into master.

I don't see how rebasing often and keeping a linear history is in any way a worse workflow than letting merge bubbles happen. To the contrary, I've changed my preferences from the latter to the former because it turned out to be more readable and to make it easier to find commits that introduced bugs or contain badly done merges.

If there's more than one person working on the code base, rebasing is only safe if you restrict pushing/pulling in some way. Properly interleaving pushes and rebases is just more mental load and another way to shoot yourself in the foot with git.

And I don't see the point just to get prettier git-log output - I've never had an issue finding commits or diffing across more than one commit.

But like I said, I've given up arguing about it and have reluctantly embraced my inner rebaser. A small part of me still feels it's a regression.

If your rebasing only rewrites history up to a point that's shared by everyone working on the same branch as you, I don't see what's the big problem.

> And I don't see the point just to get prettier git-log output - I've never had an issue finding commits or diffing across more than one commit.

You haven't, others (like me) have...

If your team is rebasing already public history, then you’re right. Is that what you’re talking about? History should be cleaned up locally before pushing elsewhere. Once pushed, history shouldn’t be rewritten except in emergencies, and even then it should be discussed and communicated and everyone should agree a rewrite is better than more pushes to fix the problem. A case where a rewrite is preferable is when someone accidentally checks security keys into git, for example.

Rebasing before pushing should be embraced, are you sure that’s not the majority of what’s happening?

The issue is its easy to screw up this advice. This is like saying only look down the barrel of a gun if you know its not loaded.

How so? And which part? I think it’s difficult to rebase already pushed history accidentally, because that requires a force push. You have to opt-in and take action to do it, so it’s not easy to screw up unintentionally.

Well you can say having to force is a solid barrier but you'll see plenty of comments suggesting that as well as plenty of comments stemming from having had to clean it up.

Sure, but that’s completely different from your hyperbolic analogy of looking down the barrel of an unloaded gun. Force push has a solid barrier, it is not default behavior, it gives you warnings, the manual gives warnings, and if you read anything online you’ll find many warnings against. If people still do it not knowing what they’re doing, yes it can definitely cause problems, but you can’t call it an accident or easy to screw up.

It's ultimately a tooling problem - Git doesn't have a good way of "tagging" feature branches to be ignored. It's concept of branches is limited - There's only places where there's more than one parent commit, and which is which is unclear. If you handle it badly, you end up with an unreadable history, littered with 'f' commits and junk, rather than having a nice linear history you can run regressions on.

I don't think this is a problem with Git, per-se - I think it's a problem with the tooling we use to interpret it, and the tooling we use to commit to it. But there's a lot of "valid but invalid" ways you can use it, and writing good tooling for different flows is hard, so nobody's invested in it a bunch.

Because a git history is meant to be read efficiently