How to Flatten git Commits

One of my least favorite tasks as a software engineer is resolving merge conflicts. A simple rebase is a frequent occurrence but the rare massive conflict is inevitable when many engineers work in a single codebase. One thing that helps me deal with large rebases with many merge conflicts is flattening a branch’s commits before fixing merge conflicts. Let’s have a look at how to flatten those commits before resolving those conflicts!

My typical command for rebasing off of the main branch is:

# While on the feature branch...
git rebase -i master

To flatten commits before the rebase, which can make resolving merge conflicts easier, you can slightly modify the original command:

# While on the feature branch...
# git rebase -i HEAD~[NUMBER_OF_COMMITS]
git rebase -i HEAD~10

The example above would flatten the last 10 commits on the branch. With just one single commit, you avoid the stop-start nature of fixing merge conflicts with multiple commits!