Git Merge and Rebase

Introduction

Version control systems (VCS) like Git enable collaborative software development by tracking changes to codebases. Two vital operations in Git are merge and rebase, both of which integrate changes from one branch into another.

Git Merge

What is Git Merge?

Git merge is the process of combining changes from different branches in a repository. It creates a new commit that brings together the histories of merged branches.

How to Merge in Git

Ensure you are on the branch you want to merge into (e.g., `main`).
Fetch the latest changes:
```
git fetch origin
```
Merge the desired branch (e.g., `feature-branch`):
```
git merge feature-branch
```

Note: Merging preserves the history of both branches, which can lead to a more complex history graph.

Git Rebase

What is Git Rebase?

Git rebase is an alternative to merging that moves or combines a sequence of commits to a new base commit. This results in a cleaner project history.

How to Rebase in Git

Checkout the branch you want to rebase:
```
git checkout feature-branch
```
Rebase onto the target branch (e.g., `main`):
```
git rebase main
```

Tip: Rebase is useful for keeping a linear project history, but be cautious when rebasing shared branches.

Merge vs Rebase

Key Differences

Merge preserves the history of both branches, while rebase creates a linear history.
Merge results in a merge commit, whereas rebase rewrites commit history.
Rebase is generally preferred for local changes, while merge is used for integrating branches in a shared repository.

Best Practices

To make the most of merge and rebase, consider these best practices:

Use merge for integrating changes from long-lived branches.
Use rebase for cleaning up local commit history before merging.
Avoid rebasing commits that have been pushed to shared branches.
Regularly pull changes from the main branch to minimize merge conflicts.

FAQ

What happens if I rebase a branch with conflicts?

You will need to resolve conflicts manually. Once resolved, continue the rebase using git rebase --continue.

Can I revert a rebase?

Yes, you can use git reflog to find the commit before the rebase and reset to it.

Is it safer to merge or rebase?

Merging is generally safer for shared branches since it preserves history. Rebase is cleaner but can lead to loss of history if not handled carefully.