Fetching single tag in shallow clone almost unshallow the clone

Hi,

I have a copy of Golang repository [1] on my local Git server on my computer. I'm experimenting with fetching single tags in shallow clone.

I begin with shallow clone the repo:

$ git clone https://<myhost>/path/to/go.git --depth 200 golang $ cd golang

Because only one, default branch (master) is checked out on shallow clone, I fetch latest release branch shallowly:

$ git remote set-branches --add origin release-branch.go1.16 $ git fetch origin release-branch.go1.16 --depth 25

Then I fetch single tag only, that is latest tagged release:

$ git fetch origin tag go1.16.4 --no-tags

That above worked, because the commit the tag refers to is already on the clone.

But when I fetch a single tag which the commit the tag refers to isn't already on the clone, Git fetched almost the entire history (thus almost unshallow the clone):

$ git fetch origin tag go1.16.1 --no-tags

I expect that instead Git will deepen the shallow clone until the specified tag.

Note that I used "almost unshallow" phrase, because although almost the whole history had been fetched, `.git/shallow` still exists, meant that the clone was still shallow. To convert to full clone, I did `git fetch --unshallow`, which also fetched tags referenced on either master or already configured released branches.

Thanks.

[1]: https://github.com/golang/go

On 5/28/2021 3:03 AM, Bagas Sanjaya wrote:> But when I fetch a single tag which the commit the tag refers to isn't already on the clone, Git fetched almost the entire history (thus almost unshallow the clone):

You should add a --depth here, too. Git doesn't remember that you want a certain depth, because that doesn't work in perpetuity.

You are hitting the issue I documented in my comparison between partial and shallow clones [1]: The commit history for go1.16.1 goes "around" your shallow boundary. See the image immediately above the "Comparing Clone Options" section.

[1] https://github.blog/2020-12-21-get-up-to-speed-with-partial-clone-and-shallow-clone/#user-content-shallow-clones

Thanks, -Stolee

Hi,

OK. I can specify --depth that I want, but often I forget how deep my clone when fetching tag with --depth, so that it has the same depth as before fetching tag. What should I do?

So basically when I request fetching something out of shallow boundary, Git "unshallow" by fetching the whole remaining history (but not implies --unshallow).

I found out that shallow clones perform on repos that have linear history policy (that is no merge commits). For example, on linear history repo, deepening shallow clone with `git fetch --deepen <n>` deepens the shallow boundary by <n> commits, whereas on repo with merge commits, doing the same may drastically zig-zag number of commits on the clone (at one instance can be more commits, at the other can be fewer).