Day 32: Rebase Replays Your Commits, and a Restore Inherits Everything You Don't Override

Today's two tasks are both about a new base. A feature branch that needs to sit on top of a master that has moved. A database instance that needs to come back from a snapshot taken when things were fine. In each case, the interesting question is the same: what carries over, and what do you have to say out loud? One Git task, one AWS task. Rebase a feature branch onto master without creating a merge commit, then snapshot an RDS instance and restore it into a new one. The tasks come from the KodeKloud Engineer platform. Rebase: not moving commits, replaying them The requirement was specific, and the specificity is the lesson. A developer's feature branch was behind master. Bring it up to date without losing any feature work, and without a merge commit. That second clause rules out git merge master . Merge joins two histories and records the join, which is the merge commit. Rebase does something else entirely. cd /usr/src/kodekloudrepos/media git branch git log --oneline --graph --all --decorate git checkout feature git rebase master git log --oneline --graph --decorate Git's own documentation describes what happens under git rebase master : it lists the commits on your branch that are not on master, checks out master, and then replays each of your commits on top of it, one at a time, in a way it compares to running git cherry-pick for each one. Replays. Not moves. Every commit that comes out the other side has a new hash, because a commit's identity includes its parent, and the parent is different now. Your work is preserved, the commits carrying it are not the same objects they were. That is exactly why there is no merge commit. Rebase does not join two histories, it rewrites yours so it looks like it was always based on master's current tip. You get a straight line, at the cost of a history that is no longer a record of what actually happened. Two things I had to be deliberate about. Direction. Rebase applies to the branch you are standing on and takes the branch yo