> I remember plenty of people who used SVN saying why did they need to use git

I remember everyone saying “SVN is a piece of shit, I hate it, why can’t I easily create branches.” Also mixed revisions which was the worst part of it.

The jj people should really write a guide to show how it’s better than git because, so far, I’m still very confused and we’ve had that conversation on HN at least 10 times without anyone giving concrete examples.

For me, jj is better than git because it has achieved something of a holy grail: it is both simpler and more powerful, at the same time. It achieves this by having more cohesive primitives.

Take the index. I love(d) git’s index. It is a powerful way to build up focused commits. Jj does away with the index, yet gives you equivalent power. How? Because instead of a separate index concept, jj has a special name for a commit representing the index: @. Files are (by default) automatically tracked and included in @. Just like how you’d git add -p, you create a new commit for your work, then create a commit on top of it. As you work, @ gets built up with your code, and when you’re ready, jj squash (with various flags or paths to control exactly what gets added) to move them into your parent, “real” work commit.

So if it’s the same, why is it better? Because we’ve reduced the number of states: instead of dirty, staged, and committed, you just have committed. And with that, commands are simpler: no distinction between —hard or —soft for something like git reset, everything just operates on committed state. This means you can bring the full set of tools to manipulate commits to bear on your index!

The same goes with stashing: because heads are allowed to be detached, to use the git terminology, we don’t need a special stash concept: create a new commit that’s forward of where you’re working to “stash” your changes in there until you need them.

These are two simple examples, but it’s really about how everything fits together into an extremely powerful and cohesive tool.

And I remember everyone saying that git is confusing, that they get into states that they don’t understand and have to blow their local changes away, and that they have completely fucked their local copy more than once.

I’ll give you some concrete advantages:

1. Every time you run a `jj` command a snapshot of your local changes is made. I don’t know about you but often while I’m working on something experimental I have an idea for a slightly different approach, try it out, it doesn’t pan out, and I’m like fuck I wish I’d saved where I was an hour ago. git won’t do that for you but jj will.

2. The rebase workflow is dramatically better. Rebasing multiple commits with conflicts is excruciating. You have to fix it right here and right now but you’re in a weird repo state where you can’t easily to another commit and tweak it or look at the state of things at different times. It’s a pain in the ass and easy to get wrong. With jj there are no weird intermediate rebase states. Rebasing always succeeds and if there are conflicts you’re able to address them just by editing your changes as you would in any other situation.

3. I don’t have to make WIP commits or stash when switching between lines of work and I don’t have to remember to undo them when I come back. Your work is always committed. Stashing doesn’t need to exist any more and as a result I never have to worry about conflicts when unstashing. I never have to realize I’ve forgotten work that was stashed.

4. Named branches don’t follow you automatically. This is huge if you ever have to do some linear work that involves multiple PRs that have to be merged and deployed one by one by one. With git you have to make branch after branch after branch. And god help you if one of the earlier lines of work needs to be changed, now you have to rebase all the descendants. With jj all this work is linear. If you have to edit an earlier commit or insert a new commit inbetween two, it’s trivial.

5. And the real killer feature? I get to have all this and nobody on my team needed to change a thing for themselves.

I was a git expert. I’ve used it since before GitHub. I’ve written a barebones implementation of git from scratch. I was the guy everyone came to when they got stuck. I gave talks on git to my local language user meetup. And I will never need to touch it again.

> Every time you run a `jj` command a snapshot of your local changes is made.

I think that's going to be pretty divisive. For projects where your input is here, your output is there, and that's that I imagine it's fine. Getting people to implement one of the workarounds to avoid junking up the repo feels like a huge ask.

I’ve found most modern codebase have good gitignore discipline, but it’s true that there are codebases that are not. There are also some tools that by default write files to the current directory.

The auto add feature is configurable these days though, so if you don’t like it, you can turn it off.

Auto-adding your changes to existing files sounds like a great feature, auto-adding any random files it finds in the project is a terrible one. I can't imagine why the author decided that was a good idea. Can someone explain the reasoning behind it? I can understand someone wanting it as some point so it makes a certain amount of sense to add as an option, but not as the default. Makes me wonder about what other bad decisions have gone into the project.

It’s consistent and convenient.

I was skeptical until I tried it.

I'm a bit more than skeptical. Right now, for a project at work, looking at files in the repo (for testing, etc) I have 294 files untracked and 10 ignored. Using jj all but the ignored files would be committed to the repo and I'd have to something akin to git's filter-branch to clean them out again to avoid that bloat.

I guess I should ask... is that final step made super easy? That is does jj make it easy to completely remove all traces from the repo of those auto-added files (like filter-branch)?

You live with those files showing up as untracked because it was easy and convenient to do so with git.

If git auto-added them from the get go, you would have used a pattern in your personal or project gitignore to skip them, or you would have put them into an ignored tmpdir, or you would keep them on a separate branch if you intend to make them part of the repo. None of these steps would have felt painful or out of place. You see files you don’t intend to include in `jj status` and you’d do whatever is appropriate to exclude them.

I’m with Steve here. I too was skeptical, and it’s turned out to be a complete non-issue.

> and I'd have to something akin to git's filter-branch to clean them out again to avoid that bloat

It’s even more trivial than you might imagine. If you have a commit that added files you don’t want to include you `jj edit` that commit, remove them however is appropriate (rm, mv, add to gitignore, whatever), and… there is no step 3. Later commits are instantaneously and automatically rebased so as to not include those files. Tools like filter-branch are completely unnecessary.

Cool. You've convinced me. A small change in workflow + easy cleanup sounds like it addresses most of my concerns. Though if I were to adopt jj I'd still probably just turn off the feature at first until I saw where I could have used it in practice. I'm going to wait and see for a bit myself. I'm pretty comfortable with git.

The way jj tracks changes isn't a feature you can turn off AFAIK. Maybe you can, but if you can, you shouldn't. This is fundamental to the jj internals and workflow.

As someone who also kept a lot of files in their repo that went untracked, it was a small adjustment. Add to my .gitignore, untrack the files, and done.

You can disable automatically adding untracked files to the repo, but you can't disable it from automatically incorporating changes to tracked files. I believe GP was talking about the former.

Yes. It was specifically adding untracked files automatically.

> The auto add feature is configurable these days though, so if you don’t like it, you can turn it off.

That's one of the workarounds I had in mind. :)

This week I've had to work with CSVs, SQLite databases, and video in... six... different formats. Some goes in the repo, some doesn't.

It seems like my choices are:

- Disable it in the repo's .jj/repo/config.toml.

- Get people that don't like it to turn it off.

- Get people to do their exploratory coding in a gitignored directory.

It feels like any choice I make is going to be met with resistance.

You don’t have to convert your team to use jj. So there’s nobody to resist but yourself.

For me, writing temporary output to a gitignored tmp directory has been trivial. And I do exploratory coding in a separate branch. Just because it’s part of the repo doesn’t mean it needs to get pushed.

> You don’t have to convert your team to use jj. So there’s nobody to resist but yourself.

Currently, sure. I was more thinking about it as a possible Git successor.

The post you’re replying to gave 2 concrete examples.

I get what you are saying about the nicer workflows for those cases.

However, why would the contributors to jj not just try to make git better by addressing these weaknesses?

I’m not being glib, just that it puzzzles me when a new oss comes out that does the same thing as another tool but a a bit different. I would have though that there is a way to have a git plug-in or even a way to contribute to git to enhance the issues outlined.

Yes, I know that some code bases are too far gone for major enhancements…

> However, why would the contributors to jj not just try to make git better by addressing these weaknesses?

Because the git workflow causes a lot of the difficulty and fixing it involves making a new concept: mutable changesets with a unique id which are built on top of immutable commits.

jj isn’t just some bugfixes or a few porcelain improvements, it deeply changes the way you approach things. And there’s a pretty decent amount of unlearning of subtly-broken concepts you need to do.

None of that could ever make its way into git.

In some sense they already are making git better since that’s the data format that the tool supports.

Also, some of the UI improvements or even protocol improvements might make it into git eventually.

I’m skeptical about it being worthwhile to switch to a new backend. Maybe it would work if it’s just local, but a lot of IDE plugins and other tools would need to be written, and git has lots of inertia.

> why would the contributors to jj not just try to make git better by addressing these weaknesses?

Because jj isn't being built to improve git, but to allow using git at Google to work on Piper-backed code instead of hg/fig, and adding support for the abstractions that are needed to support git and piper was probably seen as free complexity on git's side.

This is slightly incorrect. I started it because I believed in the idea of modeling the working copy as a commit, but it's true that I made the storage pluggable from the beginning because I wanted to be able to convince my team at Google that we should use it internally too.

I thought it was simply a response to git5/git-multi getting deprecated once fig became popular.

I'm a bit surprised then, that's one of the things that has kept me from trying it as it feels weird to not have that much control over what gets into the commit. Using magit doesn't help as it's just way too good once you get used to it.

Think of it this way: they are trying to make git better by addressing fundamental weaknesses in git, but some of those weaknesses require a fundamentally different UI paradigm and as such aren’t practical to upstream, hence a new project.

> I’m not being glib, just that it puzzzles me when a new oss comes out that does the same thing as another tool but a a bit different. I would have though that there is a way to have a git plug-in or even a way to contribute to git to enhance the issues outlined.

You would have thought? Plugins? Git doesn’t have plugins to my knowledge. Hooks are not plugins for security reasons. Meaning you can’t distribute hooks, have people install them and call it an extension.

Then, assuming that they could just make Git better. Are they interested in supporting all of Git plus their new work? Why would they be?

If anything, lazygit has shown it is possible to have more natural workflows on top of git as demonstrated by https://www.youtube.com/watch?v=CPLdltN7wgE, so it is indeed possible

Merges were so, so painful in SVN, though. Maybe SVN improved towards the end of its life? I remember everyone went well out of their way to avoid needing to merge until git, because it could take hours to resolve a heavily-conflicted tree.

People complain constantly about how painful git is when their simple workflows break down. It is legendarily complicated and difficult to use.

But when an alternative comes along and long-term git users try to tell people how much better it is? Everyone immediately forgets all their issues and frustrations. It’s honestly kind of bizarre.

Anecdata: I have no issues with my simple git workflow that I’ve used at the previous 3 companies I’ve worked for. As long as communication is solid across teams/people, merge conflicts and rebasing isn’t that big of a pain to introduce an un proven tool to an org.

My thought would be that most people are happy and it’s the <5% of people who complain the loudest that are heard.

> to introduce an un proven tool to an org

Your org doesn’t have to adopt the tool. Nobody on my team needs to know or care that I use jj instead of git. The only people who do know or care have themselves switched when I showed it off to them.

I’ve worked too many places where I’ve helped fix too many coworkers’ broken git repos to believe in a simple git workflow. Basically everyone uses the same fetch/branch/commit/merge-to-main approach and people still constantly run into problems. None of the people with some claimed simple workflow are doing anything meaningfully different than what everyone else is doing.

It’s just astonishingly easy to internalize all the fixes and band aids we’ve adopted to smooth the sharp edges and forget how often we have to work around them.

But I don’t see the complaints that were claimed. I help people as well. They learn, and we move on. If they don’t learn then we have another problem to solve.

I will admit there is occasional call where I have to get someone out of a twisted pretzel, but that is few and far between.

You don’t deal with rebase conflicts? You don’t ever unstash to the wrong branch? Or to the right branch, but it was changed and now it’s applied uncleanly? You don’t ever want to go fix a previous commit? You don’t ever need to do linear work that gets merged one piece at a time into the trunk?

All of these things (and others) can be worked around with varying levels of annoyance ranging from just living with it to new commands that help out to changing your workflow to completely avoiding some workflows. But in my experience nearly everyone deals with those annoyances on a semi-regular basis.

With a proper workflow and communication, only the first one (rebase conflicts) is a semi-regular occurrence (once a month). The others I have never had to do while working on a team. We establish a clear way of working and everyone abides by it.

And before you say well this doesn’t work with a bigger team, my team is 8 and the org is 50 on the same codebase. At “google scale”, I understand this might not be the same case.

If someone has to go out of that workflow to fix a previous commit on main, they submit a pr on top of latest.

Again, I don’t see the major complications here. It seems to me to be fixing a communication issue in an org more than anything.

Point 3 is dishonest, imo.

jj has no evidence today to support the idea that it will be a main tool in the future. An even heavier burden of proof comes from the idea that it could be adopted by mainstream forges, so it's certainly not an argument on how jj is better than git.