Why Git Repositories Get Heavy: The fundamental reason a Git repository becomes heavy is due to the immutable nature of its objects. Every time you make a change, a new blob, tree, or commit object is created. This ensures your history is never lost, but it also means that every version of every file is permanently stored.
1. Storing Large Files in the .git/objects Folder
The most common cause of a massive .git/objects directory is the presence of large files. Git is not designed to handle binary files like images, videos, audio files, or compressed archives efficiently. When you commit a large file, Git stores a complete copy of it as a blob object. If you then modify that file, even slightly, and commit it again, Git creates an entirely new blob object for the new version.
Imagine you have a 100 MB video file.
- Commit 1: You add the file. Git creates a 100 MB blob object. Your repository is now 100 MB.
- Commit 2: You make a small edit to the video and commit. Git creates a new 100 MB blob object. Your repository is now 200 MB, even though the change was minimal.
- Commit 3: You revert to the original video. Git creates a third 100 MB blob object. The repository size is now 300 MB.
This happens because Git’s delta compression within packfiles is not as effective on binary data as it is on plain text. Binary files often have very few similarities, making it difficult for Git to find a base object and store only a small delta. The end result is a repository that grows to massive sizes, even with just a few commits of large binary files.
2. Bloating the Repository with Accidental Commits
Another common source of bloat is the accidental commitment of large files that should never have been in the repository in the first place. This includes:
- Build artifacts: Files like
.jaror.exefiles. - Large log files: These can grow rapidly.
- Dependency folders: Such as
node_modules, which can contain thousands of small files.
Once an object has been committed to the repository, it’s almost impossible to completely remove it from the history without a drastic action like using git filter-repo or BFG Repo-Cleaner. A simple git rm command only removes the file from the working directory and the next commit; the original blob object remains in the .git/objects folder as part of the project’s history.
3. The Role of Packfiles and Redundant Objects
While Git uses packfiles to compress objects and save space, the process is not perfect. Unreferenced or “dangling” objects that are not part of any commit history can still exist in the .git/objects directory, taking up space. This can happen, for example, if you add a file to the index but then never commit it, or if a branch is deleted. These objects are not immediately removed. Git’s git gc (garbage collection) command is designed to clean up these loose objects and repack the repository for efficiency, but it doesn’t run automatically all the time.
How to Address a Bloated Repository
To prevent and fix a heavy Git repository, you need to be proactive:
- Use
.gitignore: The most important rule is to prevent large and unnecessary files from being committed in the first place. A well-maintained.gitignorefile is your first line of defense. - Implement Git LFS (Large File Storage): For projects that legitimately need to version large binary files, Git LFS is the recommended solution. Instead of storing the large file itself in the
.git/objectsfolder, Git LFS stores a small text pointer in the repository and hosts the actual binary file on a separate server. This keeps the Git repository small and fast while still allowing for version control of large files. - Rewrite History to Remove Bloat: If a large file has already been committed to the repository, the only way to remove it is by rewriting the history. This is a powerful but dangerous operation that should be done with extreme care, as it changes the SHA-1 hashes of all subsequent commits. Tools like
git filter-repoorBFG Repo-Cleanercan automate this process, but they are not a substitute for proper repository hygiene.