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Date: Thu, 2 Feb 2012 09:45:35 -0500
Message-ID: 
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Subject: Re: Unique instance IDs?
From: Robert Newson <rnewson@apache.org>
To: dev@couchdb.apache.org
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... 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 <kevin.r.coombes@gmail.com> wrot=
e:
> For CouchDB, I think UUIDs are clearly the way to go. =A0After all, given=
 the
> UUID, database, =A0and hostname, you can construct the desired URL direct=
ly by
> forming
> =A0 =A0http://hostname:5984/database/UUID
> As Noah points out, if you used this entire URL as the identifier (by whi=
ch
> I assume he means the _id field), then you would lose the ability to copy
> the document elsewhere. =A0This would, of course, break replication
> completely.
>
> Keeping the UUIDs as they are gives the best of both worlds. =A0Easy
> 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 po=
int
> to each document.
>
> =A0 =A0-- 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 o=
f
>> 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 th=
e
>> web using that address. I might also want to put my cool essay on Dropbo=
x,
>> 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 o=
f
>> 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 tha=
t
>> 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 wh=
en
>> 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
>>
>