为什么 git 浅克隆可以有更多的提交<depth> ?

Question

git clone --depth <depth> <url> <repo>; git -C <repo> rev-list --count --all git clone --depth <depth> <url> <repo>; git -C <repo> rev-list --count --all != <depth>

git clone --depth <depth> : Create a clone with a history truncated to <depth> commits . Implies --single-branch .

Eg url = https://github.com/vhf/free-programming-books.git , depth = 10, but commit_count = 15

git version 2.9.0

Answer 1

The shallow version of the repository includes all commits within the specified distance from the branch head when following all possible parents rather than only the first one. Therefore, for a non-linear history with merges, the count of commits will not be equal to depth.

$ git clone --depth 10 https://github.com/vhf/free-programming-books.git
Cloning into 'free-programming-books'...
remote: Counting objects: 85, done.
remote: Compressing objects: 100% (63/63), done.
remote: Total 85 (delta 31), reused 46 (delta 22), pack-reused 0
Unpacking objects: 100% (85/85), done.
Checking connectivity... done.

$ git -C free-programming-books/ rev-list --count HEAD
15

$ git -C free-programming-books/ log --graph --oneline --decorate
* b9ffc8e (HEAD -> master, origin/master, origin/HEAD) Adding pt_BR C book used by ...
* 824c1d3 Replaced Google Python style guide dead-link with new one (#1987)
* 3c32612 Added Laravel: Code Smart online book (#1986)
* eabce2c Fixed typo: Structure and Interpretation (#1985)
* aab83e5 Added IRPF90 gitbook to Misc section (#1984)
* 6f72509 Added a bash tutorial in free-courses-en.md (#1983)
*   9b95b09 Merge branch 'pr/1980'
|\  
| * 2811cd3 Fix blank lines
| * bbe9bd6 Adds 2 golang podcasts (and fixes missing #ggulp)
| * fdeabc6 (grafted) Fix ordering
*   da317ad Merge branch 'pr/1976'
|\  
| * 20b940a Fix ordering
| * 9a6ee0b (grafted) Add openHPI to list of MOOCs
* 43294d1 Update link Rust by Example #1970 (#1995)
* d758a93 (grafted) Fix a broken link to 'Practical PostgreSQL' (#1994)

The pseudo-root commits in this truncated history are d758a93 , 9a6ee0b , and fdeabc6 . All of them are 9th generation ancestors of the head commit.

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Original answer (before the MVCE was provided)

This may be the case with local clones when <url> doesn't start with file:// . Then git outputs a corresponding warning:

warning: --depth is ignored in local clones; use file:// instead.

For local clones git simply creates hardlinks to objects in the source repository (unless the --no-hardlinks switch is specified, but the latter still doesn't make local clones respect the --depth option). Cloning via hardlinking allows to save disk-space and is very fast compared to copying all objects. Since the purpose of the --depth option is to reduce the data transfer, it doesn't make much sense for local clones and is therefore ignored.