Current State

Meaningful Commits

Only 6 meaningful commits

Remaining commits are all noice adding no value

Typical PR commit history

Text

• Branch created and merged in a day
• Still has 3 merge commits
• 1 real fix, but the changes are spread across 4 commits
• If the PR takes time to merge, it gets bad

Current Problems

• Git history is very complicated. Difficult to track when happened and when
• Too many merge commits, creating no real value.
• High traffic repo, so had to merge master into pullrequest branch multiple times
• Difficult to see all the changes done in a repo to fix a particular OM ticket. The changes are spread across multiple commits
• Makes it difficult to cherry pick and give a hot fix when needed

Another PR

• Lot of review comments
• Still managed to have no merge commits
• He also managed to do all the changes in a single commit !
• Isn't he an awesome developer ?

Another PR

Of course Palanivel is an awesome developer :)

Proposed Solution

Git Rebase

Git Rebase VS Git Merge

• Sample repository with diverging branches
• Feature branch is behind master

Git Merge

• One flavor of merge. We merge feature into master
• Creates a merge commit
• If the feature is not developed fully, we merge master into feature which creates merge commit in the feature branch

Git Rebase

• Replays all the commits done in the feature branch on the latest master commit
• No merge commit
• Cleaner git history

Original State

Git Rebase

• Rebase rewrites git history
• Do not do if multiple people are working on the same branch
• Never do this on "master" or "priority" branches

Why should we use Rebase?

• Majority of the time, a single developer owns a feature branch / Pull request
• He commits multiple times during the course of the PR lifetime
• Gets review commits and makes more changes
• Master 99% of the time will get diverged,forcing him to merge from master , creating merge commit.
• Thereby adding lot of noise to git history.

Precaution that we should take to support Rebase

• Prevent force push to master and priority branches. This can be done in bitbucket
• Educate our developers to understand merge vs rebase master. A lot of material available online. This is a hot topic in git community.