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From: Antony Blakey <antony.blakey@gmail.com>
To: couchdb-user@incubator.apache.org
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Subject: Re: Auto-adding additional fields on PUT/POST? (datetime stamps)
Date: Thu, 4 Dec 2008 09:46:43 +1030
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On 04/12/2008, at 9:31 AM, Chris Anderson wrote:

> On Wed, Dec 3, 2008 at 2:50 PM, Antony Blakey  
> <antony.blakey@gmail.com> wrote:
>>
>> On 04/12/2008, at 9:07 AM, Chris Anderson wrote:
>>
>>> It should just be clear that timestamps are the application's
>>> business, not the database's.
>>
>> But it's possible for Couch to be the application, especially if  
>> you use
>> your apps-in-the-db approach. I'm not sure I see any fundamental  
>> difference
>> between a validation function in a design document and some  
>> javascript in an
>> attachment, of even a function inan _external handler.
>>
>
> The problem with writing from the validation functions is that you are
> supposed to be able to trust them. Eg, if you look at the function,
> you can know what contract holds on the data that passes through it. A
> timestamp on new docs doesn't pass this test. There's no way to know
> whether the timestamp was added by a different function. With proper
> pass/fail validations, you know that running the same validations at
> replication time will give the same pass/fail result as at original
> write time.

IIUC, replication conflicts in a P2P configuration allow for a  
situation where even a validator that is purely funtional wrt the  
database state can generate different results upon replication. Or  
maybe I'm missing something?

Antony Blakey
-------------
CTO, Linkuistics Pty Ltd
Ph: 0438 840 787

A reasonable man adapts himself to suit his environment. An  
unreasonable man persists in attempting to adapt his environment to  
suit himself. Therefore, all progress depends on the unreasonable man.
   -- George Bernard Shaw