Re: Clone a repository with only the objects needed for a single tag

[Ben Lau <benlau@ust.hk>]

Hi Junio,

  It works!  Thanks a lot.

  However, it has a problem when involves the gitk/git-log. Because the 
parent commit is missed in the shallow repository, gitk would complain 
the object is missed and exit immediately. To solve the problem, i added 
a pair of
ID of the new root object into .git/info/grafts.

Example:

  $ cat .git/info/grafts
  741b2252a5e14d6c60a913c77a6099abe73a854a 
741b2252a5e14d6c60a913c77a6099abe73a854a

git-log/gitk do not complains afterward, but it also make gitk shows 
nothing during run. Any solution?

 By the way, although I am not sure do any other people also require 
this feature, I wish the process could be more smooth.  As the 
git-shallow-pack script do not destroy and modify any thing in the 
cloned repository beside the newly created pack file, I would suggest it 
can run the script in the 'monthership' repository, take out
the pack file to another directory or remote machine. And then build a 
new git repository based on the pack file.

  To achieve the process, it need another script that could create a git 
repository from pack file. Do any similar script existed?

Junio C Hamano wrote:

>Ben Lau <benlau@ust.hk> writes:
>
>  
>
>>  Is there any method to clone/copy a repository with only the
>>objects needed for a single tag in order to save disk space?
>>  For example, if I want to start a new project based on a
>>specific version of kernel like v2.6.14. I would run
>>`git-clone` and then checkout a new branch based on the tag.
>>    
>>
>
>Depends on what you want to do in that shallow copy.
>
>If the only thing you would want to do is to build it, then you
>could 'git-tar-tree v2.6.14' and extract that on your notebook.
>The output is just a tar so there will no history, though.
>
>If you want to develop while on the road, but do not
>particularly need to be able to inspect the history beyond the
>point you started, you could create a deliberately broken
>repository, using the git-shallow-clone script (attached), like
>this:
>
>    $ git clone -n $mothership satellite
>    $ cd satellite
>    $ git-shallow-pack --all
>    $ rm -f .git/objects/pack/pack-*
>    $ mv pack-* .git/objects/pack/.
>
>If the original repository you are cloning from is local, you
>could instead do:
>
>    $ git clone -l -s -n $mothership satellite
>    $ cd satellite
>    $ git-shallow-pack --all
>    $ rm .git/objects/info/alternates
>    $ mv pack-* .git/objects/pack/.
>
>You could develop in this repository, even build up your own
>commit chains, and when you come back you could push from this
>repository back to your 'mothership' repository.  In essense,
>any operation that does not require you to have full history
>should work.
>
>One important thing that would not always work would be to pull
>into this repository over git-aware protocols, although pulling
>from your 'mothership' repository would probably work most of
>the time.
>
>One case that would probably break is if the mothership side
>reverted a commit beyond this shallow-pack boundary and then you
>try to pull from there.  After the revert, the trees and blobs
>in that new commit you will be pulling from the mothership are
>likely to be the same as the ones contained in commits before
>the shallow clone is made.  Because your satellite repo would
>claim to have everything that is reachable from the tip (as of
>the time the clone was made) of the branch, you cannot complain
>if the mothership side assumes you must have those blobs and
>trees and did not send them to you when you pull.
>
>---
>#!/bin/sh
># git-shallow-pack
>
>git-rev-parse --revs-only --no-flags --default HEAD "$@" |
>while read sha1
>do
>	echo "$sha1"
>	while type=`git-cat-file -t "$sha1"` &&
>	      case "$type" in tag) ;; *) break ;; esac
>	do
>		next=`git-cat-file tag "$sha1" |
>			sed -ne 's/^object //p' -e q`
>		echo "$next"
>		sha1="$next"
>	done
>	git-rev-parse --verify "$sha1^{tree}" 2>/dev/null &&
>	git-ls-tree -r "$sha1" | sed -e 's/^[0-7]* [^ ]* //'
>done |
>sort -k 1,1 -u |
>git-pack-objects pack
>
>
>
>
>
>  
>