X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=Documentation%2Fgit-filter-branch.txt;h=7ffe03f4279a8ca8110806260f33a58f849351e4;hb=1973b0d790155b5d8a32a6f7401116fad2205721;hp=451950bab67702a236c55e77d6f3a0723a812488;hpb=ddebfd1f27110bbcd0e8da0417bc425509af219a;p=git.git

diff --git a/Documentation/git-filter-branch.txt b/Documentation/git-filter-branch.txt
index 451950bab..7ffe03f42 100644
--- a/Documentation/git-filter-branch.txt
+++ b/Documentation/git-filter-branch.txt
@@ -212,6 +212,11 @@ git filter-branch --index-filter 'git rm --cached filename' HEAD
 
 Now, you will get the rewritten history saved in HEAD.
 
+As with using `rm filename`, `git rm --cached filename` will fail
+if the file is absent from the tree of a commit.  If it is not important
+whether the file is already absent from the tree, you can use
+`git rm --cached --ignore-unmatch filename` instead.
+
 To rewrite the repository to look as if `foodir/` had been its project
 root, and discard all other history:
 
@@ -334,6 +339,47 @@ 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`.  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 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 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).
+
+
 Author
 ------
 Written by Petr "Pasky" Baudis <pasky@suse.cz>,