VCS comparison table

[James Henstridge]

On 25/10/06, Carl Worth <cworth at cworth.org> wrote:
> On Wed, 25 Oct 2006 18:08:22 +0800, "James Henstridge" wrote:
> > If there aren't, or you made the merge by mistake, you can make a call
> > to "bzr revert" to clean things up without ever having created a new
> > revision.
>
> One result of this approach is that developers of different trees
> don't necessarily have common revision IDs to compare. Imagine a
> question like:
>
>         When you ran that test did you have the same code I've got?
>
> In git, the answer would be determined by comparing revision IDs.

Can you really just rely on equal revision IDs meaning you have the
same code though?

Lets say that I clone your git repository, and then we both merge the
same diverged branch.  Will our head revision IDs match?  From a quick
look at the logs of cairo, it seems that the commits generated for
such a merge include the date and author, so the two commits would
have different SHA1 sums (and hence different revision IDs).

So I'd have a revision you don't have and vice versa, even though the
trees are identical.


> In bzr, the only answer I'm hearing is attempting a merge to see if it
> introduces any changes. (I'm deliberately avoiding "pull" since we're
> talking about distributed cases here).

Or run "bzr missing".  If the sole missing revision is a merge (and
not the revisions introduced by the merge), you could assume that you
have the same tree state.


> And to comment on something mentioned earlier in the thread, there's
> no need for "wildly complex" distributed scenarios. All of these
> issues are present with developers working together as peers, (and
> each considering their own repository as canonical).
>
> A harder question (for bzr) is:
>
>         Do you have all of the history I've got?
>
> (The problem being that when one developer is missing some history and
> merges it in, she necessarily creates new history, so there's never a
> stable point for both sides to agree on.)

Why does it matter if they create a new revision?  They can still tell
if they've got all the history you had.

James.