Subject: Re: [PATCH] Documentation: pruning recipe for destructive filter-branch

From: Junio C Hamano <[email-masked]>
Date: Fri, 13 Feb 2009 17:07:30 -0800

Thomas Rast <[email-masked]> writes:

> diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
> index 1fbbbb4..737c555 100644
> --- a/Documentation/git-filter-branch.txt
> +++ b/Documentation/git-filter-branch.txt
> @@ -339,6 +339,42 @@ git filter-branch --index-filter \
>  ---------------------------------------------------------------
>  
>  
> +
> +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`.  If you want to physically shrink the
> +repository afterwards, you have some choices:
> +
> +* Clone it with `git clone file:///path/to/repo`.  The clone will not
> +  have the removed objects.  See linkgit: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 (in this order).  This is a very destructive
> +approach, so *make a backup* or go back to cloning it.  You have been
> +warned.

Sounds sane so far and even somewhat amusing.

> +* Make sure you really removed all variants of a filename, if a blob
> +  was moved over its lifetime.  `git log \--follow \--all \-- foo` can
> +  help you find renames.
> +
> +* Make sure you really filtered all refs: use `\--tag-name-filter cat
> +  \-- \--all` when calling git-filter-branch.

Don't these two apply equally to "git clone" approach?  Only the remaining
four are specific to in-place pruning, if I am reading this correctly.

> +* Make sure you 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`.
> +
> +* Repack to remove packed objects with `git repack -ad`.
> +
> +* Prune unpacked unreferenced objects with `git prune \--expire=now`.
> +
> +
>  Author
>  ------
>  Written by Petr "Pasky" Baudis <[email-masked]>,
> -- 
> 1.6.2.rc0.274.g97213
>
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