Why rebasing creates linear history in Git - Visual Breakdown

Process Flow - Why rebasing creates linear history

Start with branch feature

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Identify commits on feature

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Find base commit on main

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Reapply feature commits on top of main

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Result: feature branch commits follow main commits

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Linear history achieved

Rebasing takes your feature commits and places them on top of the latest main branch commits, making the commit history a straight line.

Execution Sample

Git

git checkout feature
git rebase main

This moves the feature branch commits to be after the latest commits on main, creating a linear history.

Process Table

Step	Action	Current HEAD	Resulting Commit History
1	Checkout feature branch	feature	main -> A -> B (feature commits)
2	Start rebase onto main	feature	main -> A -> B (to be reapplied)
3	Reapply commit A on main	feature	main -> A -> B main -> A' (rebased)
4	Reapply commit B on A'	feature	main -> A -> B main -> A' -> B' (rebased)
5	Rebase complete	feature	main -> A' -> B' (linear history)

💡 All feature commits reapplied on top of main, creating a linear commit history.

Status Tracker

Variable	Start	After Step 3	After Step 4	Final
HEAD	feature	A' (commit A rebased)	B' (commit B rebased)	B' (feature branch tip)
Commit History	main -> A -> B	main -> A -> B main -> A'	main -> A -> B main -> A' -> B'	main -> A' -> B'

Key Moments - 2 Insights

Why do the commit hashes change after rebasing?

Because rebasing creates new commits with the same changes but different parent commits, so the hashes are new, as shown in steps 3 and 4 of the execution_table.

Does rebasing change the main branch commits?

No, main branch commits remain unchanged; only the feature branch commits are reapplied on top of main, preserving main's history as shown in the commit history column.

Visual Quiz - 3 Questions

Look at the execution_table at step 4, what is the commit history?

A feature -> A -> B

B main -> A' -> B'

C main -> A -> B

D main -> B' -> A'

💡 Hint

Check the 'Resulting Commit History' column at step 4 in the execution_table.

At which step does the HEAD point to the rebased commit B'?

A Step 4

B Step 2

C Step 3

D Step 5

💡 Hint

Look at the 'Current HEAD' column in the execution_table and variable_tracker after step 4.

If you do not rebase but merge instead, how would the commit history differ?

A It would delete feature branch commits

B It would be linear like rebasing

C It would create a merge commit, making history non-linear

D It would rewrite main branch commits

💡 Hint

Rebasing reapplies commits linearly, merging creates a new commit joining histories, see concept_flow for linear history.

Concept Snapshot

git rebase <branch>
- Moves your commits on top of another branch
- Creates new commits with new hashes
- Results in a straight, linear commit history
- Keeps main branch unchanged
- Useful for clean project history

Full Transcript

Rebasing in git takes your feature branch commits and reapplies them on top of the latest commits from the main branch. This process creates new commits with new hashes because the parent commits change. The main branch commits remain unchanged. The result is a linear history where your feature commits appear as if they were made after the main branch commits, making the project history easier to read. This is different from merging, which creates a merge commit and keeps the history branching. The commands 'git checkout feature' and 'git rebase main' perform this operation. The execution table shows each step: checking out the feature branch, starting the rebase, and replaying each commit on top of main, ending with a linear commit history.