What Is a Fast-Forward Merge?
A fast-forward merge happens when the target branch has not moved since you branched, so Git just slides its pointer forward with no merge commit.
A fast-forward merge is the simplest kind. If the branch you are merging into has not changed since your branch diverged, there is nothing to combine; Git can just move the target branch pointer up to your latest commit. The result is a perfectly linear history.
When a fast-forward is possible
A fast-forward applies only when the target branch is a direct ancestor of the branch being merged, meaning the target has had no new commits since you branched. With no divergence, there is nothing to reconcile, so Git simply advances the pointer.
Fast-forward versus merge commit
You can request or forbid a fast-forward when merging.
git merge --ff-only feature/quick-fix
# or force a merge commit:
git merge --no-ff feature/quick-fixWhy it matters
Fast-forward merges keep history linear and free of extra merge commits, which many teams prefer for readability. The downside is that the history no longer shows that a branch ever existed. Some teams force a merge commit with no-ff to preserve that record, especially for tracking pull requests.
Fast-forward merges and CI/CD
A linear, fast-forward history is the easiest to reason about in CI: each commit follows the last, so bisecting a regression and tracing a deploy back to a change is straightforward. Requiring branches to be up to date before merge often produces fast-forwards and ensures CI tested exactly what lands.
Choosing your strategy
- Allow fast-forwards for the cleanest linear history.
- Use no-ff to always record that a branch was merged.
- Require branches be current to enable safe fast-forwards.
- Pick one convention and apply it consistently.
Key takeaways
- A fast-forward merge just moves the branch pointer with no merge commit.
- It needs the target branch to have no new commits since you branched.
- Linear history from fast-forwards makes CI bisection and tracing easier.