Git Rebase vs Merge

Introduction

When working with Git, one of the most common tasks is integrating changes from one branch into another. Git provides two primary methods for accomplishing this: merge and rebase. While both achieve the goal of combining code from different branches, they do so in fundamentally different ways, each with its own advantages and use cases.

What is Git Merge?

Git merge is a non-destructive operation that combines two branches by creating a new "merge commit." This commit has two parent commits, preserving the complete history of both branches. When you merge a feature branch into your main branch, Git creates a new commit that ties together the histories of both branches.

Basic Merge Syntax

git checkout main
git merge feature-branch

What is Git Rebase?

Git rebase is a process of moving or combining a sequence of commits to a new base commit. Rather than creating a merge commit, rebase rewrites the project history by creating brand new commits for each commit in the original branch. This results in a linear, cleaner project history.

Basic Rebase Syntax

git checkout feature-branch
git rebase main

Key Differences

Aspect	Merge	Rebase
History	Preserves original history with merge commits	Creates linear history by rewriting commits
Commits	Adds merge commit with two parents	Replays commits on new base
Safety	Safe for public branches	Risky on shared branches
Readability	Can become cluttered with many merges	Clean, linear history
Traceability	Easy to see when branches were merged	Harder to trace integration points
Conflicts	Resolve once during merge	May resolve multiple times per commit

When to Use Merge

• Working on public or shared branches
• You want to preserve the complete history of your project
• You need to see when and where branches were integrated
• Working in a team where others may have pulled the branch
• Merging long-lived feature branches or release branches

When to Use Rebase

• Cleaning up local commits before pushing
• Updating a feature branch with latest changes from main
• You want a linear, clean project history
• Working on a private branch that hasn't been shared
• Preparing commits for a pull request

Interactive Rebase

One powerful feature of rebase is interactive mode, which allows you to modify commits during the rebase process. This is extremely useful for cleaning up your commit history before merging into a main branch.

git rebase -i HEAD~3

Interactive rebase allows you to:

• Reorder commits
• Edit commit messages
• Squash multiple commits into one
• Split commits into smaller ones
• Delete commits entirely

Best Practices

For Merge

• Use merge for integrating completed features into main branches
• Consider using --no-ff flag to always create a merge commit
• Write descriptive merge commit messages
• Use merge for public branch integration

For Rebase

• Only rebase local, unpublished commits
• Use interactive rebase to clean up commits before creating pull requests
• Rebase feature branches regularly to stay up-to-date with main
• Communicate with your team when rebasing shared branches

Common Workflows

Feature Branch Workflow with Rebase

# Create and work on feature branch
git checkout -b feature-branch
# ... make commits ...

# Update feature branch with latest main
git checkout main
git pull
git checkout feature-branch
git rebase main

# Clean up commits interactively
git rebase -i main

# Merge into main (creates merge commit)
git checkout main
git merge feature-branch

Simple Merge Workflow

# Create and work on feature branch
git checkout -b feature-branch
# ... make commits ...

# Update main and merge
git checkout main
git pull
git merge feature-branch
git push