VCS comparison table

[Lachlan Patrick]

Linus Torvalds wrote:
> 
> On Thu, 19 Oct 2006, Aaron Bentley wrote:
>> I understand your argument now.  It's nothing to do with numbers per se,
>> and all about per-branch namespaces.  Correct?
> 
> I don't know if that is what Carl's problem is, but yes, to somebody from 
> the git world, it's totally insane to have the _same_ commit have ten 
> different names just depending on which branch is was in.
> 
> In git-land, the name of a commit is the same in every branch.

I've been following the git-vs-bzr discussion, and I'd like to ask a
question (being new to both bzr and git). How does git disambiguate SHA1
hash collisions? I think git has an alternative way to name revisions
(can someone please explain it in more detail, I've seen <ref>~<n>
mentioned only in passing in this thread). It seems to me collisions are
a good argument in favour of having two independent naming schemes, so
that you're not solely relying on hashes being unique.

A strong argument is that a global namespace based on hashes of data is
ideal because the names are generated from the data being named, and
therefore are immutable. Same data => same name for that data, always
and forever, which is desirable when merging named data from many
sources. But the converse isn't true: one name does not necessarily map
to only that data. Have I misunderstood? Is this a problem?

Ta,
Loki