Re: [HACKERS] pgsql: /home/peter/commit-msg

Magnus Hagander wrote:
> On Mon, Nov 16, 2009 at 08:29, David Fetter <david(at)fetter(dot)org> wrote:
>> On Mon, Nov 16, 2009 at 06:56:54AM +0200, Peter Eisentraut wrote:
>>> Yeah, sorry guys. I fixed the CVS log message now.
>> Strangely, the git repo still shows the old message. For the record,
>> there's the new one:
>
> I don't find that strange at all.
>
> In git, the commit message is part of the commit, and thus the SHA1.
>
> If it changes, it would be a different commit. Which would change
> history and break the repositories of anybody pulling from it.
>
> So it's not only not strange, I'm very happy it didn't pull those
> changes and broke my repository :-)

Yeah, I'm glad it didn't do anything funny with the mirror.

> Now, if we want to "correct" that the way to do it is to rebuild the
> git mirror from scratch and have everybody start over, I think :-)
> While you're not supposed to change history in any RCS, git makes it a
> lot harder than cvs to do it...

Nah, you'd only have to back out to the commit before the one that was
broken. And actually git provides quite simple commands to do that, see
git-reset for example. I forget how exactly the mirroring software
works, but I presume it would then see that commit as a new one, as well
as anything on top of it, and mirror them.

Rewriting git history like that would mean that anyone who has pulled
from the mirror since that commit happened would get an error the next
time they try to pull/fetch again. But you can easily get over that by
doing "git fetch --force".

So we could rewrite the git history too, and I think it would be quite
nice to have the right commit message there as well. But I don't care
enough to volunteer to do the legwork. If we are going to do it, we
should do it as soon as possible, while we're only a couple of commits
ahead of that point. It's going to be more painful later on.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com