Merge strategies overview in Git - Commands & Configuration

Introduction

When working with Git, you often combine changes from different branches. Merge strategies decide how these changes come together. Choosing the right strategy helps keep your project history clear and avoids conflicts.

When you want to combine a feature branch into the main branch after finishing work

When you need to update your branch with the latest changes from another branch

When you want to keep a clean, linear history without extra merge commits

When you want to preserve the exact history of changes including merge points

When you want to resolve conflicts manually during merging

Commands

This command merges the 'feature-branch' into your current branch using the default merge strategy, which creates a merge commit if needed.

Terminal

git merge feature-branch

Expected Output

Updating 1a2b3c4..5d6e7f8

Fast-forward

 file.txt | 2 ++

 1 file changed, 2 insertions(+)

This forces Git to create a merge commit even if the merge could be done with a fast-forward, preserving the branch history.

Terminal

git merge --no-ff feature-branch

Expected Output

Merge made by the 'recursive' strategy.

 file.txt | 2 ++

 1 file changed, 2 insertions(+)

→

--no-ff - Create a merge commit even if fast-forward is possible

This merges changes from 'feature-branch' by combining all commits into one, but does not create a merge commit automatically. You must commit manually.

Terminal

git merge --squash feature-branch

Expected Output

Squash commit -- not updating HEAD

Automatic merge went well; stopped before committing as requested

→

--squash - Combine all changes into one commit without creating a merge commit

If a merge causes conflicts and you want to stop and return to the state before merging, this command cancels the merge.

Terminal

git merge --abort

Expected Output

Merge aborted

→

--abort - Cancel the current merge and restore the previous state

Key Concept

If you remember nothing else from this pattern, remember: merge strategies control how Git combines branches and affect your project history.

Common Mistakes

Using 'git merge' without understanding fast-forward merges

It can create no merge commit, making it hard to see when branches were combined

Use 'git merge --no-ff' to always create a merge commit if you want clear branch history

Running 'git merge --squash' and expecting an automatic commit

Squash merges do not create a commit automatically, so changes remain unstaged

After 'git merge --squash', run 'git commit' to finalize the merge

Ignoring conflicts during merge and forcing commit

This can cause broken code or lost changes

Use 'git merge --abort' to cancel and fix conflicts before retrying

Summary

Use 'git merge' to combine branches with a default strategy that may fast-forward.

Use '--no-ff' to keep merge commits and preserve branch history.

Use '--squash' to combine all changes into one commit without a merge commit.

Use '--abort' to cancel a merge if conflicts occur.

Practice

1. What does the --no-ff option do when merging branches in Git?

easy

A. It creates a merge commit even if a fast-forward merge is possible.

B. It squashes all commits into one before merging.

C. It deletes the source branch after merging.

D. It aborts the merge if conflicts are found.

Solution

1. Step 1: Understand fast-forward merges

   A fast-forward merge moves the branch pointer forward without creating a new commit if no divergent changes exist.

2. Step 2: Effect of --no-ff

   The --no-ff option forces Git to create a merge commit even if a fast-forward is possible, preserving branch history.

3. Final Answer:

   It creates a merge commit even if a fast-forward merge is possible. -> Option A

4. Quick Check:

   --no-ff keeps history with merge commit [OK]

Hint: Remember: --no-ff always makes a merge commit [OK]

Common Mistakes:

• Confusing --no-ff with --squash
• Thinking it deletes branches
• Assuming it aborts on conflicts

2. Which of the following is the correct syntax to perform a squash merge of branch feature into main?

easy

A. git merge --squash feature

B. git merge feature --no-ff

C. git merge --fast-forward feature

D. git merge --abort feature

Solution

1. Step 1: Identify squash merge syntax

   The --squash option is used with git merge to combine all commits from the source branch into one commit on the target branch.

2. Step 2: Check command correctness

   git merge --squash feature is the correct syntax to squash merge the feature branch into the current branch.

3. Final Answer:

   git merge --squash feature -> Option A

4. Quick Check:

   Squash merge syntax = git merge --squash [OK]

Hint: Use --squash right after git merge for squash merges [OK]

Common Mistakes:

• Placing --no-ff instead of --squash
• Using --abort which cancels merges
• Assuming --fast-forward is a valid option

3. Given the following commands run on branch main:

git merge feature

If feature has 3 commits and no conflicts, what will be the result in the commit history?

medium

A. A single new merge commit combining all changes from feature.

B. Merge aborted due to conflicts.

C. Three separate commits from feature added to main with no merge commit.

D. No new commits; main pointer moves forward (fast-forward).

Solution

1. Step 1: Understand default merge behavior

   By default, if the main branch has no new commits since branching, Git performs a fast-forward merge, moving the main pointer forward.

2. Step 2: Analyze the scenario

   Since feature has 3 commits and main has no new commits, Git will fast-forward main to feature's tip without creating a merge commit.

3. Final Answer:

   No new commits; main pointer moves forward (fast-forward). -> Option D

4. Quick Check:

   Default merge with no divergence = fast-forward [OK]

Hint: If no new commits on main, merge fast-forwards [OK]

Common Mistakes:

• Assuming a merge commit is always created
• Thinking commits are duplicated
• Confusing conflicts with no conflicts

4. You tried to merge branch feature into main using git merge feature, but Git reports conflicts. What is the best way to resolve this?

medium

A. Delete the feature branch and start over.

B. Run git merge --abort to cancel the merge and lose changes.

C. Manually edit conflicting files, then run git add and git commit.

D. Use git reset --hard to force merge.

Solution

1. Step 1: Understand merge conflicts

   Conflicts occur when Git cannot automatically combine changes. Manual intervention is needed to fix conflicting files.

2. Step 2: Resolve conflicts properly

   Edit the conflicting files to fix issues, then stage changes with git add and complete the merge with git commit.

3. Final Answer:

   Manually edit conflicting files, then run git add and git commit. -> Option C

4. Quick Check:

   Resolve conflicts manually, then add and commit [OK]

Hint: Fix conflicts manually, then add and commit [OK]

Common Mistakes:

• Aborting merge loses progress
• Deleting branches unnecessarily
• Using reset which discards changes

5. You want to merge a long-lived feature branch into main but keep the commit history clean with a single commit representing all changes. Which merge strategy should you use and what is the correct sequence?

hard

A. Use git merge --no-ff feature to keep all commits and a merge commit.

B. Use git merge --squash feature then commit manually.

C. Use git rebase main feature then fast-forward merge.

D. Delete feature and copy files manually.

Solution

1. Step 1: Identify goal - single commit for all changes

   Squash merge combines all commits from the feature branch into one commit on main, keeping history clean.

2. Step 2: Correct merge sequence

   Run git merge --squash feature to prepare changes, then create a new commit manually with git commit.

3. Final Answer:

   Use git merge --squash feature then commit manually. -> Option B

4. Quick Check:

   Squash merge + manual commit = single clean commit [OK]

Hint: Squash merge then commit for one clean commit [OK]

Common Mistakes:

• Using --no-ff which keeps all commits
• Confusing rebase with squash merge
• Deleting branches instead of merging