Linear vs Non-Linear Merge

When it comes to merging in Git, the terms linear and non-linear refer to the structure of the commit history that results from the merge process.

Linear Merging

Linear history means the project history forms a single straight line—no branches sticking out. This is usually achieved by using:

git rebase

• It re-applies commits from your branch on top of another (like main), creating new commits.
• This makes the history look like the feature was developed directly on top of the latest main.

git merge --ff-only

• Ensures a fast-forward merge (only if possible).
• No new merge commit is created; the branch pointer just moves forward.

Benefits

• Clean, easy-to-follow history.
• Useful in smaller teams or personal projects.

Example

git checkout feature
# work done on feature branch
git fetch origin
git rebase origin/main
git checkout main
git merge feature  # fast-forward

Non-Linear Merging

Non-linear history means the commit graph contains merge commits and branching paths—more like a tree.

git merge (default)

• Creates a merge commit when two branches diverged.
• Preserves full history and context of parallel work.

Benefits

• Shows real collaboration and when branches were combined.
• Important in large teams or open-source projects where preserving context matters.

Example

git checkout main
git merge feature
# Creates a merge commit with both histories preserved

Summary: Linear vs Non-Linear Merge

Caution

• Rebasing public/shared branches can rewrite history and cause confusion.
• Always prefer merge over rebase for shared branches unless everyone agrees on rebase usage.