Re: Bad objects error since upgrading GitHub servers to 1.6.1

[Jeff King <peff@peff.net>]

On Tue, Jan 27, 2009 at 11:14:56PM -0800, Junio C Hamano wrote:

> I've been toying with an idea for an alternative solution, and need
> somebody competent to bounce it around with.

Well, unfortunately for you, you are stuck with me. ;P

> Here is my work in progress.  It introduces "ignore-missing-negative"
> option to the revision traversal machinery, and squelches the places we
> currently complain loudly and die when we expect an object to be
> available, when the color we are going to paint the object with is
> UNINTERESTING.
> 
> I have a mild suspicion that it may even be the right thing to ignore them
> unconditionally, and it might even match the intention of Linus's original
> code.  That would make many hunks in this patch much simpler.

I'm not sure it is a good idea to do so unconditionally. In the case of
negatives for transferring files, a missed negative is simply a missed
opportunity for optimizing the resulting pack.

But in other cases, it silently gives you the wrong answer.  For
example, consider a history like:

       C--D
      /
  A--B
      \
       E--F

now let's suppose I have everything except 'E'. If I ask for

  git rev-list F..D

then it will not realize that A and B are uninteresting, and I will get
A-B-C-D. I think it is much better for git to complain loudly that it
could not compute the correct answer.

Am I understanding the issue correctly?

-Peff