Version Control System (VCS)

• Centralized Version Control System (CVCS)

1. Ex: CVS, Subversion, Perforce
2. We may encounter the errors/bugs in the center.
3. When errors occur, we only last the Individual Snapshots on local devices.

• Distributed Version Control System (DVCS)

1. Ex: Git, Bazaar
2. Client not only copy codes, but the complete image of repo and history.

Git History

• Use Distributed Version Control System: BitKeeper (2002-2005)
• Advantages of Git:

1. Quick
2. Simple
3. Non-linear Distribution (Allow lots of branches)
4. Maintain the large-scale project: Linux Kernel

What's Git

• Git is similar to other VCS like Subversion, but treat data in a different way.
• Most VCSs store data with Document-List based (CVS, Subversion, Perforce, Bazaar, it's also called Delta-based VCS.
• Git treat documents as series of snapshots:

1. At each staged, it would create a snapshot based on current files, and store the index of snapshot.
2. If files aren't changed, Git would create a link, pointing to last-stored files.
3. A.K.A Git Flow

Local Machine

1. Most instructions are accessed with local machine and resources.
2. Thus, we have the complete history of the repo.

Advantages of Git: Integrity

1. Git would create/generate the checksum before storing data.
2. Standard of hash: SHA-1, SHA-256.
3. Git store data with index based on the checksum of docs contents, not the name of docs.

The status of Git

• Modified
• Staged
• Committed