Git squash history after merge

Question

I merged an upstream of a large project with my local git repo. Prior to the merge I had a small amount of history that was easy to read through, but after the merge a massive amount of history is now in my repo. I have no need for all the history commits from the upstream repo.

There have been other commits made after this upstream merge that I would like to keep. How do I squash all that history that was merged from the upstream into one commit while keeping the commits made after the upstream merge?

Answer 1

I was able to squash several commits after multiple merges from the master branch using the strategy found here: https://stackoverflow.com/a/17141512/1388104

git checkout my-branch            # The branch you want to squash
git branch -m my-branch-old       # Change the name to something old
git checkout master               # Checkout the master branch
git checkout -b my-branch         # Create a new branch
git merge --squash my-branch-old  # Get all the changes from your old branch
git commit                        # Create one new commit

You will have to force an update if you need to push your squashed branch to a remote repository that you have previously pushed to, e.g. git push origin my-branch -f