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From: Paul Davis <paul.joseph.davis@gmail.com>
Date: Mon, 12 Dec 2011 11:01:13 -0600
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Subject: Re: Unique instance IDs?
To: dev@couchdb.apache.org
Content-Type: text/plain; charset=ISO-8859-1

On Mon, Dec 12, 2011 at 1:09 AM, Jason Smith <jhs@iriscouch.com> wrote:
> On Mon, Dec 12, 2011 at 5:16 AM, Paul Davis <paul.joseph.davis@gmail.com> wrote:
>>> A couch URL is its unique identifier. A database URL is its unique
>>> identifier. This sounds like a too-clever-by-half optimization. IMHO.
>>>
>>> --
>>> Iris Couch
>>
>> To this I ask simply: What's the URL of my phone? Tying a URL to a
>> database is like identifying a person by their address. A UUID per
>> created database is much more fine grained, but has operations issues
>> with file handling and what not.
>
> Hi, Paul. A database is not a person. It is a resource, with a
> universal location.
>
> Databases can be replicated, or copied, or restored from backup. (Same
> for .ini files.)
>
> One .couch file can be served from different URLs; and one URL might
> serve different .couch files over time. The current replicator
> understands this and if anything seems fishy, it double-checks. (For
> example, the instance_start_time helps to detect wholesale replacement
> of .couch files.)
>
> The web assumes that mostly, but not always, a stable URL represents a
> stable resource. So does the replicator. Getting away from that seems
> difficult.
>
> --
> Iris Couch

I think you've contradicted yourself. If a URL is the universal name
for a database, then how are we able to server different databases
from the same URL?

Tying a database to a URL is merely an artificial limitation because
we haven't thought of anything better. If we *did* think of a way to
uniquely identify databases that didn't break due to ops requirements
then that would be a much better fit to the CouchDB model. It is
difficult but that's because we haven't yet thought of a good way to
deal with what happens OOB when ops teams change server
configurations.