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From Damien Katz <dam...@apache.org>
Subject Re: Changing rev to _rev in view results (Was: Re: newbie question #1)
Date Mon, 29 Dec 2008 14:21:23 GMT
Yes, it is perfectly clear to a newbie, because it's the simplest  
case. That's why I coded it this way initially, it seemed simpler.

What isn't immediately obvious  is all the other special fields that  
can appear in documents and in other contexts. How to make that  
consistent? I tried, but couldn't keep it simple. The problem was  
special names in various structures no longer have a simple rule to  
follow, but instead you must know if this field appears in a document  
at any time, then it starts with underscore in other structures.

The current rule maybe not the most intuitive to a newbie, but it is  
far more consistent and easier to work with then when using the deeper  
APIs. The only 2 other workable solutions I see is to either stuff  
everything special into a _meta structure or only use HTTP headers for  
all CouchDB meta information. But after having spent much time  
thinking about this issue, I think the current rule is the better  
compromise.

-Damien

On Dec 29, 2008, at 8:58 AM, Geir Magnusson Jr. wrote:

> That rule would have been perfectly clear to me as a newbie.
>
> +1
>
> geir
>
> On Dec 29, 2008, at 8:55 AM, Antony Blakey wrote:
>
>>
>> On 29/12/2008, at 11:11 PM, Damien Katz wrote:
>>
>>> The problem was there where other reserved fields in documents  
>>> that started with underscore, but in other places the fields  
>>> wouldn't have an underscore. Keep track of which fieldname had  
>>> underscores and where became confusing. The rule was changed to be  
>>> simpler to understand and deal with.
>>
>> A simpler rule is: _rev is the name no matter where it appears,  
>> same with _id. I'd go so far as say that this kind of rule is so  
>> fundamental to our idea of identity and naming, that it doesn't  
>> even count as a rule. And there had better be a really good reason  
>> to introduce a rule contrary to such an strongly implicit and  
>> intrinsic concept.
>>
>> And as far as 'Keeping track of which fieldname had underscores",  
>> it would seem that the current situation is the worst, because you  
>> have to keep track not based on identity e.g. _rev and _id, but  
>> rather on context, which is a dynamic and more intellectually  
>> demanding concept than semantic identity. Furthermore, in this  
>> scheme, names must be mapped under structural transformation (such  
>> as copying the _id and _rev fields from one context to another),  
>> which complicates generic transformations.
>>
>> IMO the name isn't "rev" with sometimes an underscore, rather the  
>> name IS "_rev". Same with "_id".
>>
>> A single name for a concept, lexically consistent, is less  
>> cognitive load both initially and on an ongoing basis.
>>
>> Antony Blakey
>> -------------
>> CTO, Linkuistics Pty Ltd
>> Ph: 0438 840 787
>>
>> The ultimate measure of a man is not where he stands in moments of  
>> comfort and convenience, but where he stands at times of challenge  
>> and controversy.
>> -- Martin Luther King
>>
>>
>


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