[Couchdb Wiki] Update of "Git_At_Apache_Guide" by MarkStruberg

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The "Git_At_Apache_Guide" page has been changed by MarkStruberg:
http://wiki.apache.org/couchdb/Git_At_Apache_Guide?action=diff&rev1=1&rev2=2

  
  This is a work in progress.
  
+ ASF GIT repositories are currently hosted at http://git-wip-us.apache.org/
+ 
+ == Main difference between SVN and GIT ==
+ For understanding the setup of our GIT repositories better, we have to understand the difference in the mechanics of GIT compared to what we had available before at the ASF.
+ 
+ ||<tablestyle="width: 903px; height: 203px;"> ||SVN||GIT||
+ 
+ ||<tablestyle="width: 903px; height: 203px;">Content||SVN handles the content on a per-file basis. Each file is basically versioned on it's own and has it's own history. Moving a file with svn mv will preserve this history. Just copying the file will not!||GIT treats all the files in the repository as a big union. All the commits basically form a tree of diffs which get applied to the initially empty project directory. There is no 'native history' on a file basis because of that. For producing a git-log or git-blame, GIT needs to walk through all the commit tree and check whether the given file is involved. Otoh git can not only automatically track rename-files, but also perfectly tracks if you move a method from one class to another!||
+ ||Security||Handled by SVN itself. It's perfectly possible to have different directories and files in a SVN repo which have different security rules applied. ||GIT has no own security. It solely relies on the underlying transport/filesystem. It's imo not possible to have ||
+ ||Branches||SVN creates an own directory per branch in ./branches/{branchname}/. The main content is always in ./trunk/||GIT treats branches more like the way CVS did. When checking out a branch, the directory remains the same, only the content will get 'switched'. Each branch is technically equal. It is NOT possible to only do 'partial' branches (on a partly tree of the project), instead a branch is ''__always__'' in the whole repository!||
+ ||Tags||Similar to SVN branches. They are held in ./tags/{tagname} and basically a read-only svn copy of trunk. ||Tags in GIT are just a name to a specific commit-sha1. Basically just a shortcut for the sha1. Like with branches, a tag is always over the __whole__ ||
+ ||Modularisation||SVN fully supports sparse checkout and treats the checked out content without any difference whether it is a full project tree or just a sub-project||GIT originally didn't know any sparse checkout. This capability only got added in git-1.7.0 and works quite different. You will still get the whole tree content in your .git/objects. Also all tags and branches performed on such a sparse checked out project will still cover the whole repo. There is support for git-submodules, but this is more similar to the flat project mapping of Eclipse than a real nested project structure. ||
+ || || || ||
+