Re: rewriting pathnames in history

[Sam Vilain <sam@vilain.net>]

Jeff King wrote:
> I recently ran into an interesting situation with git. I created a
> repository that consisted of several directories (and files in them).
> Later, after many commits, I realized I would prefer each directory have
> its own git repository. That is, given a repo with the files:
>   foo/bar
>   baz/bleep
> I wanted two repos, "foo" containing the file "bar" and "baz" containing
> the file "bleep".

Nice work, but I think you should be able to get it *really* fast, much 
faster than that.

Instead of replaying a checked out copy, just go through the commit 
history, and when the treeID for that subdirectory has changed, then 
that directory has a new revision.  So, make a new commit object with 
that as the treeid.  in other words, you'll be constructing a very 
lightweight branch, but with its tree IDs all corresponding to 
sub-directory treeids on the combined branch.  The history ripple script 
that was posted the other day probably has most of the pieces you need. 
  Once this is done, you can just clone that branch to "get it out".

Sam.