commitobjekt

A commitobjekt is a fundamental data structure in modern distributed version control systems, most notably Git. It records a single set of changes and the resulting state of the repository at a point in time. In English-language sources it is typically called a commit object; in German-language contexts the term commitobjekt is commonly used.

Structure and contents: A commitobjekt references a tree object that represents the project state after the commit. It contains zero or more parent commit identifiers (one for a linear history, multiple parents for merges) and metadata such as author and committer information, timestamps, and the commit message. Optional fields may include a cryptographic signature, such as a GPG signature.

Identification and storage: Each commitobjekt has a unique identifier derived from its contents through a cryptographic hash (for example, SHA-1 in traditional Git, with SHA-256 available in newer configurations). The commit's hash serves as its permanent ID and links to the related tree and parent(s), forming a directed acyclic graph that records the project’s history.

Metadata roles: The author field records who originally created the changes, while the committer field logs who applied the changes to the repository. Timestamps accompany both, and the commit message documents the intent and description of the changes.

Immutability and history operations: Commitobjekte are immutable; changes to history create new commits. Tools reconstruct history by traversing the commitobjekt graph, performing diffs, merges, and blame analysis. Commit objects are transferred between repositories as part of packfiles during fetch and push operations.

Practical notes: Understanding commitobjekt is essential for grasping how Git records, shares, and revises changes. While the English terminology is widely used, the German term commitobjekt appears in some documentation and discussions of Git’s object model.