What is Git Graph?
An explanation of Git Graph's purpose, importance, and how it integrates with Git's architecture.
Git Graph is a powerful extension to Git that enables semantic tracking, diffing, and merging of graph files. By introducing specialized behavior for these files, Git Graph elevates your workflow, allowing you to handle complex graph structures with the same simplicity you enjoy for source code.
While you don't need to master the inner workings of the git-graph binary to take full advantage of its features, understanding its design can help you troubleshoot issues when they arise.
How Git stores files
At its foundation, Git treats commits as complete snapshots of your project. Every commit represents the full state of your repository at a given time—a bit like a self-contained archive (similar to a tarball or zip file). However, storing the complete snapshot of thousands of files with every commit would be extremely inefficient.
To overcome this, Git uses a mechanism called content-addressable storage. Instead of saving duplicate copies of unchanged files, Git breaks data into objects called blobs. Each blob is identified by a unique hash (formally, an Object ID or OID) based on its content. This approach not only minimizes storage by deduplicating identical content across commits but also enables efficient version tracking.
Additionally, Git employs delta compression (also known as delta encoding) to further optimize repository size. After commits are recorded, internal processes (triggered by commands like git repack or git gc) identify similar objects and store only the differences. This method works remarkably well for text-based files (such as source code) but is less effective for compressed or high-entropy binary files.
Why Git Graph exists
The strategies used by Git work excellently for text and code, but they are less suited for graph files and other specialized data formats that require semantic understanding. Traditional approaches like Git Large File Storage (Git LFS) focus on reducing repository bloat by offloading large binary data—but they don't offer semantic awareness.
Git Graph fills this gap by providing a similar interface to Git LFS, but its focus is on enabling semantic tracking and intelligent diffing of graph files. This specialized treatment means that users can benefit from both Git's efficiency in handling file content and Git Graph's nuanced understanding of complex graph structures.
Note: You can use Git Graph alongside Git LFS. This combination allows you to store large binary files externally while applying semantic operations on graph files.
How Git Graph works
Git Graph is designed to work seamlessly with the standard Git interface. One of the key design choices behind Git Graph is the way it can be executed as a native Git command.
When you type a Git command that isn't recognized as one of Git's built-in commands, Git automatically searches for an executable in your PATH whose name begins with git-. This mechanism allows you to extend Git's functionality without altering the core Git codebase, and is the reason why Git Graph executable is named git-graph.
Git Graph works by extending Git's behavior only for files identified as graph files. It leverages Git's configuration system by injecting custom drivers—named graph—that modify Git's default handling of git diff, git merge, and git difftool operations for these files.
Git Graph introduces three main drivers:
- diff: Converts graph files into a human-readable text format (e.g. JSON) so that differences can be easily visualized.
- merge: Handles merge conflicts in graph files by applying semantic rules that understand the structure and meaning of the data.
- difftool: Provides semantic differences between graph files.
Once you run the command git graph install, Git Graph configures your repository by adding the necessary driver settings to your Git configuration (e.g. .git/config). The configuration file will include entries similar to the following:
You can verify these settings by running the git graph env command:
As you can see, git-graph is used as a configuration manager for graph drivers, and as a command to execute them.
When you mark certain files to be tracked as graph files (using the git graph track command), Git Graph will add an entry to the .gitattributes file (see the gitattributes documentation for more information), seamlessly modifying how Git processes these files. This approach allows Git Graph to integrate deeply with Git while keeping the core workflow unchanged.
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