I don't think it's such a slam-dunk, but maybe I'm guilty of a
goal-tending violation.
It depends on whether you intend to keep replicating the two copies to
keep them synchronized. If you want that (and most of the time, I do),
then I think it's an advantage to keep the same "UUID". The (matching)
internal UUIDs indicates that you think of these two things as the same
abstract entity. The full URL distinguishes the "physical" copies.
If on the other hand, you expect the copies to evolve into something
differently over time, then I can see how you might want different
UUIDs. But again, the full, easy-to-construct URL distinguishes them.
As far as I can tell, the existing system still lets you have it both
ways....
On 2/2/2012 8:45 AM, Robert Newson wrote:
... until you copy the database (and its uuid) and have two databases
with the same uuid. This has always been the slam-dunk argument
against database uuid's.
B.
On 2 February 2012 09:41, Kevin R. Coombes<[email protected]> wrote:
For CouchDB, I think UUIDs are clearly the way to go. After all, given the
UUID, database, and hostname, you can construct the desired URL directly by
forming
http://hostname:5984/database/UUID
As Noah points out, if you used this entire URL as the identifier (by which
I assume he means the _id field), then you would lose the ability to copy
the document elsewhere. This would, of course, break replication
completely.
Keeping the UUIDs as they are gives the best of both worlds. Easy
replication, and (as long as the database is hosted at the same place) an
easy way for humans and programs to construct stable URIs or URLs that point
to each document.
-- Kevin
On 1/22/2012 12:44 PM, Noah Slater wrote:
Sorry to bump this old thread, but just going through my backlog.
With regard to URLs, I think there is some confusion about the purpose of
a
URL here.
If I write a a cool essay, say, and I stick that up at
nslater.org/my-cool-essay, then I can link to it from other places on the
web using that address. I might also want to put my cool essay on Dropbox,
or post it to Tumblr, or send it in an email. Now my cool essay has lots
of
URLs. Each one of them perfectly valid. I don't have to go and edit the
original copy at nslater.org/my-cool-essay, because I am making copies of
it. My cool essay is completely unaware of the URLs that are being used to
point to it. And it doesn't care that many URLs point to it.
Yes, URLs can be used as identifiers. But when you do this, you tie the
thing you're naming to the place you're hosting it. Sometimes that is
useful, other times it will cripple you. There is nothing about URLs that
requires you to do this. I would hazard a guess that 99% of URLs are
de-coupled from the things they point to. WebArch is much more robust when
the identity of the object is de-coupled from the URL. Look at Atom, the
ID
element is supposed to be a URL, but they recommend a non-dereferencable
format, precisely to decouple posts from the location you happen to be
hosting them this month.
Hey, if we're gonna use URLs, maybe we want to go down the same route?
http://en.wikipedia.org/wiki/Tag_URI
At this point, I'm not sure what they buy us over UUIDs.
Thoughts?
Thanks,
N
