How do I split up a large Git branch into lots of smaller branches?

Question

I have imported from SVN into Git, now I have one big branch, like this:

• work on feature C
• work on feature B
• work on feature C
• work on feature C
• work on feature B
• work on feature A

I want separate feature branches, for A, B, C. I'm cherry picking commits to new branches but this doesn't remove them from the original branch so I have to manually track which ones I have pulled out.

There are around 800 commits to split up, and maybe 50 features/bugfixes.

It would be nice to have the ones I have pulled out reflected this way somehow in the git log, so I know which ones I have already done. Is this possible?

I can rebase the entire branch, skipping the commits I have pulled out, but I'm worried this will cause lots of conflicts. I don't want to resolve 500 conflicts every time I pull a commit out.

What's the best method of pulling out commits from one uber branch onto smaller feature branches, whilst keeping track of your progress?

Answer 1

What I do in this case is use interactive rebase.

At your HEAD, create your branches A, B, and C. Also create a "backup" branch (you could name it backup) in case things go wrong and you need your original HEAD back.

git branch feature-a
git branch feature-b
git branch feature-c
git-branch backup-before-rebase

Then, create a branch at the commit you want them to start from, maybe at a convenient stable commit. Call it new_trunk or something.

git checkout HEAD~50       ## this will be the new tree-trunk
git branch new_trunk

Then, do interactive rebases and pick out the commits you want to keep in that branch. Used this way, it's basically like cherry-picking in bulk.

git checkout feature-a
git rebase -i new_trunk    ## -i is for "Interactive"

When you're done, you should have 3 branches with separate histories starting from new_trunk and a backup branch reflecting the old HEAD if you still need it.