Re: Performance issue exposed by git-filter-branch

[Jonathan Nieder <jrnieder@gmail.com>]

Ken Brownfield wrote:

> I had considered this approach (and the one mentioned by Jonathan)
> but there are no git tools to actually perform the filter I wanted
> on the export in this form.

Keep in mind that the two suggestions were subtly different from one
another.

For the "filter fast-import stream" technique, apparently there is a
tool called reposurgeon[1] to do that.  git_fast_filter[2] has the
same purpose, too, if I remember correctly.

For the unpack-trees avoidance technique, true, the only example I
know if is the one I mentioned[3].  The idea would be to sort the
commits you want in topological order and replay them, for each one
going like so:

	M 040000 <old tree id> ""
	D bad/directory/one
	D bad/directory/two

using fast-import from git.git master.  (Older versions of fast-import
do not properly handle replacing the root directory, so if that sort
of compatibility is important, you'd have to use a directory listing
and fill in all the _good_ directories instead.)

I'd be glad to look at any work in this direction.  Something like it
would be useful for postprocessing when importing from svn repos.

Thanks,
Jonathan

[1] http://esr.ibiblio.org/?p=2718
[2] http://thread.gmane.org/gmane.comp.version-control.git/116028
and links therein
[3] http://thread.gmane.org/gmane.comp.version-control.git/158375