Re: [question] When an identical file is added

On Sun, Nov 24, 2024 at 02:24:19AM +0000, A bughunter wrote:

The file contents are represented as a "blob" inside the git repository, so when you add a file with identical contents, the existing blob will be reused. The file metadata (permissions, name, timestamp, etc) will be recorded as part of the tree information. If the tree information is exactly identical to an existing tree in the repository, then that tree object will also be reused.

Basically, for any object that it operates on, git will calculate the checksum. If it then finds an identical checksum already present in the tree, git will just use that existing object instead.

Reusing objects happens all the time in git. For example, imagine the scenario:

0. you have an existing repo
1. you add a file foo.c, and git commit
2. you change your mind and delete foo.c, and git commit
3. you decide you want foo.c after all, re-add it, and git commit

All tree and blob objects are identical in steps 0,2, and 1,3. However, commit objects will be different in all 4 states.

-K