Subject: Re: [PATCH-v3] Allow git-filter-branch to process large repositories with lots of branches.

From: Junio C Hamano <[email-masked]>
Date: Tue, 10 Sep 2013 16:20:01 -0700

Lee Carver <[email-masked]> writes:

> As noted in several forums, a recommended way to move trees between
> repositories
> is to use git-filter-branch to revise the history for a single tree:
>
> http://gbayer.com/development/moving-files-from-one-git-repository-to-anoth
> er-preserving-history/
> http://stackoverflow.com/questions/1365541/how-to-move-files-from-one-git-r
> epo-to-another-not-a-clone-preserving-history
>
> However, this can lead to argument list too long errors when the original
> repository has many retained branches (>6k)
>
> /usr/local/git/libexec/git-core/git-filter-branch: line 270:
> /usr/local/git/libexec/git-core/git: Argument list too long
> Could not get the commits
>
> Piping the saved output from git rev-parse into git rev-list avoids this
> problem, since the rev-parse output is not processed as a command line
> argument.
> ---
>  git-filter-branch.sh | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/git-filter-branch.sh b/git-filter-branch.sh
> index ac2a005..2091885 100755
> --- a/git-filter-branch.shgit
> +++ b/git-filter-branch.sh
> @@ -255,7 +255,7 @@ else
>  	remap_to_ancestor=t
>  fi
>  
> -rev_args=$(git rev-parse --revs-only "$@")
> +git rev-parse --revs-only "$@" > ../parse

Where is this "rev-parse" command running?  Is it always safe to
clobber the file "../parse" like this?

>  
>  case "$filter_subdir" in
>  "")
> @@ -268,7 +268,7 @@ case "$filter_subdir" in
>  esac
>  
>  git rev-list --reverse --topo-order --default HEAD \
> -	--parents --simplify-merges $rev_args "$@" > ../revs ||
> +	--parents --simplify-merges --stdin "$@" < ../parse > ../revs ||
>  	die "Could not get the commits"
>  commits=$(wc -l <../revs | tr -d " ")