Re: Change set based shallow clone

[Jakub Narebski <jnareb@gmail.com>]

Jeff King wrote:

> Many operations that look at history are going to fail with a very short
> history (e.g., finding a merge base). Some operations can work with a
> short history, but the results are probably not useful (seeing the last
> 10 commits from git-log is probably not interesting). If you just want
> the latest snapshot, the remote git-archive work going on right now will
> probably take care of that.

That is the source of the idea of _sparse_ clone, which would include e.g.
top 10 commits from each of selected branches, all commits pointed by
branches and tags, and all merge bases, and roots, joined using grafts.

E.g. if the full history looks like this.

                                    -*.|.......... head  
                                   /   |
         -*--*--*-         -*--*--x--*-|-*--*--*-- head
        /         \       /            |
 *--*--*--*--*--*--*--*--*--*--*--*--*-|-*--*--*-- head
                       \...............|.......... tag
                                       |
                                       \- [cut-off]

then the sparse clone history would look like that:
(---) denotes parentage, (...) denotes grafts below


                                       |
                           ,......x....|.*--*--*-- head
                          :            |
 *....................*--*.............|.*--*--*-- head
                       \...............|.......... tag
                                       |
                                       \- [cut-off]

of course assuming that we have no earlier commits (i.e. sparse clone, not
sparse fetch).

Of course, that solves only some of troubles...
-- 
Jakub Narebski
Warsaw, Poland
ShadeHawk on #git