The difference between merge and no-ff merge

Normally, Git uses Fast forward mode when merging branches, but in this mode, after deleting a branch, the branch information will be lost. If you want to force disabling Fast forward mode, Git will generate a new commit on merge, so that branch information can be seen from the branch history.

To put it simply, the ff mode will organize the branch history into a branch line, and the merged branch information cannot be seen, but the no-ff mode will display a fork node, and then you can see the information of the merged branch.

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Prerequisites: The warehouse has only one file, readme.txt, and only one main branch, master

1.Create a new branch dev1, modify readme.txt, and submit it under the dev1 branch

git switch -c dev1
git add readme.txt
git commit -m "dev1 branch commit"

2.Go back to the master branch and execute merge i.e. git merge dev1

git switch master
git merge dev1

3.delete branch

git branch -d dev1

4.View logs

git log --graph --pretty=oneline --abbrev-commit

5.Create a new branch dev2, modify readme.txt, and submit

git switch -c dev2
git add readme.txt
git commit -m "dev2 branch commit"

6.Go back to the master branch and execute merge

git switch master
git merge --no-ff -m "dev2 merged with mo-ff" dev2

7.delete branch

git branch -d dev2

8.View logs

git log --graph --pretty=oneline --abbrev-commit

9.Comparing the two merges, you can see the difference, the no-ff mode will record the branch history