Re: removing content from git history

["Shawn O. Pearce" <spearce@spearce.org>]

Linus Torvalds <torvalds@linux-foundation.org> wrote:
> Anyway, git-convert-objects does kind of give you a starting point. It 
> should be fixed to use "git-fast-import" or repack once in a while (so 
> that it doesn't leave tons and tons of unpacked objects), and it should be 
> fixed to fix up any commit messages that mention SHA1's that it has 
> already converted to something else, but it seems to still work. It would 
> not be impossible at all to extend the tree-rewriting logic to remove some 
> file or a particular SHA1 object you want to replace.

One idea Junio and I kicked around on #git a short while ago
was to arrange for a pipe between the current Git process
and git-fast-import, where the pipe was used from within
write_sha1_file() rather than creating the loose object.

This way an existing process like git-apply or git-convert-objects
could easily spew hundreds of thousands of objects without needing
to worry about repacking in the middle; nor would we need to worry
about the complexity of trying to disentagle the multiobject packing
parts of fast-import into some sort of library.

Obviously this is only a good idea if we are going to be making
enough objects to warrant using a packfile; small 10-20 bursts
of objects from a git-apply doesn't really justify a packfile.
But applying 100s of patches in a row might, if we could keep them
all fed through the same git-fast-import backend (and thus into
the same packfile).

-- 
Shawn.