Do you mean literally deleting your last commit? That would break a lot of the guarantees gained from the append only graph that git exploits for nearly everything it does. I think undo is too ambiguous in the context of vcs that it would be risky to introduce as a part of the cli api. What would you expect undo to do?
The commit graph is effectively append-only, but the named pointers into that graph can be reassigned at will, which means some commits can become (more or less) unreachable and eligible for garbage collection.
Yes, it is. You can't change a commit: you have to create a new one, and create copies of any child commits, which are also different commits. This generates a different graph. What changes are things like tags, branches and HEAD, but they're just pointers, not part of the graph itself.
Sure, but there's no generic "db rollback" command that reverses the last thing you did. This command would have to decide what to do for every previous command, no?
> Sure, but there's no generic "db rollback" command that reverses the last thing you did.
Technically nothing prevents the database automatically creating a subtransaction / savepoint for every operation you perform.
> This command would have to decide what to do for every previous command, no?
Yes? Not sure I see what the issue with that is.
And technically much of the information is already encoded in the reflog. The two big additional informations you’d need are:
1. Tracking changes to refs as they’re not necessarily tracked by the reflog, but there should only be a small number of plumbing operations manipulating refs so it’s not really a concern.
2. Tracking changes to the index, would likely be a lot more difficult.
> Yes? Not sure I see what the issue with that is.
The issue is that it sounds even more confusing in practice than status quo.
If you don't understand git, you can't rely on `git undo` cause you don't know what's undoable and what isn't. And if you do understand git, you don't need `git undo` in the first place, you can already undo things by yourself.
