Both solve the same problem: your feature branch is behind upstream and you want the latest code.
- Rebase replays your commits on top of the latest upstream. No extra commits. Clean history.
- Merge combines the two branches and creates a merge commit as a bookmark.
Every time you sync with upstream:
- Rebase adds 0 extra commits
- Merge adds 1 merge commit
If you sync once before opening a PR, the difference is one commit. Doesn't matter which you use.
If you sync 5 times during a long-running branch, that's 5 merge commits cluttering your log vs none with rebase.
- Your branch, your work, nobody else touching it
- Short-lived feature branches
- Right before opening a PR for a clean diff
- Shared branches (anything multiple people push to)
- Long-lived branches like
cm-qa,uat - When in doubt — merge is always the safe choice
Rebase rewrites history. If the branch has been pushed, you need git push --force after rebasing, which can blow away teammates' work. Merge never rewrites anything.
- Solo branch? Rebase is fine.
- Shared branch? Always merge.
- Only syncing once before a PR? Doesn't matter, pick either.