Git Pull vs Git Rebase: A Detailed Comparison

As a developer, you often need to incorporate changes from a remote repository into your local repository. Git offers two great ways to achieve this – git pull and git rebase. While both fetch content from a remote branch, they have some key differences. This comprehensive 2600+ word guide breaks down how git pull and git rebase work, when to use each, and dives deep on the pros and cons of both approaches.

What Does Git Pull Do?

The git pull command fetches updates from the remote repository specified and immediately merges them into your local branch.

Here is a quick overview of what happens when you git pull:

• Git communicates with the remote repository, downloads the latest changes and commits.
• The remote branch‘s head commit is merged with the local branch tip automatically.
• This creates a new merge commit to combine the diverged histories.
• The local repository now has an up-to-date, unified codebase including remote changes.

Essentially, git pull = git fetch + git merge. It‘s a convenient shortcut that handles fetching and integrating remote changes in one step.

When Should You Git Pull?

Git pull is best used when you want to quickly incorporate upstream changes from shared branches like main or develop. It shines in these collaborative workflows:

Continuous Integration Pipelines

For teams employing CI/CD pipelines, using git pull to bring in changes from the central integration branch enables rapid synchronization across the product codebase.

For example, a React app might have a pipeline setup like:

dev --> test --> stage --> production

Here, developers build features locally then push to the dev environment to have initial tests run. The git pull command can then automatically pull these changes into the test branch to begin more robust integration testing.

Keeping all environments in sync via frequent git pulling helps accelerate delivery while still allowing comprehensive testing.

Agile Scrum Teams

For agile teams adhering to methodologies like Scrum, collaborating across potentially hundreds of user stories or tasks per sprint requires tight integration.

Product owners and scrum masters often mandate pulling from a central sprint-dev branch into all feature branches daily. This frequent git pull strategy enables early discovery of conflicts and dependencies across the work items for that sprint.

By git pulling changes into their topic branches, developers can coordinating efforts more smoothly across the sprint backlog.

Open Source Projects

For open source projects with distributed teams of volunteer developers, submitting improvements requires keeping local clones in sync with the main codebase.

Frequently git pulling upstream changes from main enables contributors to submit coherent patches and additions that merge cleanly. Volunteering efforts are streamlined by reducing rejected pull requests due to simple mismatches with main.

If you need stability and want a clean single commit history, git pull likely isn‘t your best choice.

What Does Git Rebase Do?

Git rebase provides a powerful alternative to merges for incorporating changes from a remote branch. Instead of merging commits, rebasing replays commits from one branch on top of another.

When you rebase:

• Your local branch is temporarily moved to the rebase target commit.
• The rebase target branch‘s commits are applied to your local branch one by one.
• Your local branch is moved back to the end result.

So rebase replays commits like a series of cherry-picks. This results in a perfectly linear commit history!

When Should You Git Rebase?

Rebasing shines when you want a clean project history to maintain or share commits easily. Common use cases include:

Feature Branches

Long running feature branches often become out of sync with main/master. Instead of a massive merge commit from integrating changes after weeks of work, rebasing enables a gradual sync with main.

For example, consider a developer working in a branch off main over a month span:

*-*--*--*----*---*  (main)
         \
          *-*----*----> (feature-1)

Rebasing feature-1 onto main each week would replay commits like so:

                    *-*--*--*----*---*  (main)
                       \
                        *----*----> (feature-1)

Now the final merge or pull request will be trivial due to the continual sync.

Shared Repositories

Before pushing local commits to a shared central repository like GitHub, developers will often clean up history via an interactive rebase.

This gives collaborators a streamlined set of commits to review by squashing debug code, fixes into logical chunks. Less ultimate commits to evaluate.

Submitting Patchsets

When submitting fix or feature contributions via patchsets, a clean branch history with rebasing makes the submitter‘s work easier to integrate. Maintainers can simply fast-forward merge the fix without pull request size bloat.

Merge vs rebase pull request size comparison (Source: Atlassian)

As shown above, the rebase pull request contains only the relevant commits rather than including the entire duplicated history leading up to those changes.

Git Pull vs Rebase – Key Differences

While both git pull and git rebase integrate remote changes, they have some important distinctions:

	Git Pull	Git Rebase
Result	Creates merge commit	Replays commits linearly
Commit History	Has merge bubbles	Perfectly linear
Traceability	High – all points preserved	Low – old commits changed
Conflict Handling	Handles upon merge	Handles upon rebasing each commit

The workflow, context, and end goal guides which is better suited. Let‘s analyze some additional pros and cons:

Pros of Git Pull

• Simple & familiar development workflow
• Merge commits document branching history
• Easy to undo mistakes via standard revert
• Availability of visual merge tools

Cons of Git Pull

• Merge commits clutter history over time
• Harder to revert specific commits down the line
• Merge conflicts can be tricky with longer running branches
• Does not generate linear commit history

Pros of Git Rebase

• Avoids extraneous merge commits
• Linear commit history is easy to follow
• Conflict resolution can be incremental
• Cleaner pull requests and shared histories

Cons of Git Rebase

• Commits are re-written – lack authenticity
• Reconstructing old state is difficult
• Can require force pushing to remote branches
• More advanced workflow takes time to master

Carefully weigh the tradeoffs as rebasing rewrites project history – use judiciously based on scope.

When Should You Use Each?

So when should you leverage merging versus rebasing? First, identify your use case goals:

• Do you need an authoritative central source of truth branch?
• Are you integrating ongoing work or submitting finished changes?
• Does history traceability from old state matter?
• Is a clean commit log important for your purposes?

From there, this decision tree helps guide best practices:

Merge/Rebase Decision Tree (Source: Atlassian)

As shown, for centralized primary branches (like main), favor merging over rebasing to preserve history.

For local feature branches, rebasing helps keep changes in sync without cluttering logs. Then leverage pull requests to submit back up the hierarchy.

Pull vs Rebase Tutorial

Let‘s solidify understanding of these two approaches by walking through the steps live:

First, we‘ll covers git pull…

# Fetch updates from remote
git fetch origin 

# Checkout feature branch
git checkout feature-x

# Pull changes from origin/main  
git pull origin main

# Creates merge commit to integrate diverged history

Now contrast with git rebase:

# Checkout feature branch
git checkout feature-x  

# Rebase on top of origin/main
git rebase origin/main

# Feature branch commits re-played one by one
# Linear history achieved!

Running through both processes makes the resulting commit DAGs clearer:

Merge vs rebase commit history diagrams (Source: Atlassian)

In the rebase case, we avoided the additional merge bubbles for a clean timeline of changes.

Wrap Up: Merging vs Rebasing

Deciding between git pull and git rebase depends heavily on the development context at hand. Merging shine for integrations between authoritative branches when history is paramount. Rebasing excels for local features or private branches when clean logs and linearity matters.

By mastering both merge and rebase workflows, developers unlock the full flexibility of Git for continually shipping software more effectively. Analyze your specific use case, team, and outcomes to determine if merging or rebasing better serve your needs.

With some practice, you‘ll intuitionally know when to reach for pull vs rebase. Even better, you‘ll gain skills to contribute more meaningfully on collaborative projects with distributed teams.