Re: Change set based shallow clone

[Jakub Narebski <jnareb@gmail.com>]

My idea for lazy clone/fetch (lazy = on-demand) is via remote alternatives
mechanism. We put URI for repository (repositories) that hosts the project,
and we would need at start to download at least heads and tags, and only
heads and tags.

When there is request for an object (commit, tree, blob or tag) which we
don't have locally, we ask remote repository if it have it, and download it
(and perhaps some related objects); this needs extension I guess for the
git downloader ('wantonly'), it should be fairly easy for dumb downloaders
if you don't mind getting whole pack i.e. perhaps more than intended.
Perhaps 'wantonly' for git protocol should work the same: one would get
ready pack (perhaps with limit on pack size: otherwise one would get only
the requested objects).

One thing that needs extending for lazy clone is git-fsck... otherwise you
would get whole repository when calling git-fsck. Simplest would be
fsck-ing only the local part, perhaps checking if the "missing" objects are
present in remote repository, but not downloading them and not checking
connectivity further... and of course notifying user that this is lazy
clone. Unless we run git-fsck-objects on the remote side, then pass results
to the local side.

There is probably bunch of problems with this idea...
-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git