git-filter-branch: Checklist For Shrinking A Repository

git-filter-branch(1): Rewrite branches - Linux man page
http://linux.die.net/man/1/git-filter-branch

Checklist For Shrinking A Repository

git-filter-branch is often used to get rid of a subset of files, usually with some combination of --index-filter and --subdirectory-filter. People expect the resulting repository to be smaller than the original, but you need a few more steps to actually make it smaller, because git tries hard not to lose your objects until you tell it to. First make sure that:

• You really removed all variants of a filename, if a blob was moved over its lifetime. git log --name-only --follow --all -- filename can help you find renames.
• You really filtered all refs: use --tag-name-filter cat -- --all when calling git-filter-branch.
  

Then there are two ways to get a smaller repository. A safer way is to clone, that keeps your original intact.

• Clone it with git clone file:///path/to/repo. The clone will not have the removed objects. See git-clone(1). (Note that cloning with a plain path just hardlinks everything!)
  

If you really don't want to clone it, for whatever reasons, check the following points instead (in this order). This is a very destructive approach, so make a backup or go back to cloning it. You have been warned.

• Remove the original refs backed up by git-filter-branch: say git for-each-ref --format="%(refname)" refs/original/ | xargs -n 1 git update-ref -d.
• Expire all reflogs with git reflog expire --expire=now --all.
• Garbage collect all unreferenced objects with git gc --prune=now (or if your git-gc is not new enough to support arguments to --prune, use git repack -ad; git prune instead).