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From Jan Lehnardt <...@apache.org>
Subject Re: partial/diff updates?
Date Thu, 27 Nov 2008 01:14:23 GMT

On 26 Nov 2008, at 12:40, Dan wrote:

> Here is a conversation I had on the IRC channel #couchdb on this  
> subject on
> november 24, 2008 (2 days ago). Hope this helps!

I kinda don't like IRC quotes floating around, but hey, I didn't put  
up any
disclaimers either. Take the following with a grain of salt :)


> (04:01:26 PM) dsimard: I just  wanted to know if an attachment  
> changes, will
> the new revision contain just the "diff" with the old attachment or  
> the
> complete attachment?
> (04:01:49 PM) jan____: complete attachment. diffs are the devil
> (04:03:08 PM) dsimard: damn... all fields of a document are stored  
> as a full
> document?
> (04:03:18 PM) dsimard: I really thought that diffs were used
> (04:03:35 PM) jan____: no, no diffs. diffs are the devil
> (04:04:14 PM) dsimard: ok, could you elaborate on the evilness of  
> diffs?
> (04:04:44 PM) dsimard: I just want to know more about it
> (04:05:04 PM) jan____: dsimard: you need to keep diffs around  
> forever to
> construct the latest live doc. this totally conflicts with the couchdb
> storage model which uses full representations of each revision.
> (04:05:04 PM) dsimard: or if you have a good link about it
> (04:05:35 PM) jan____:
> http://incubator.apache.org/couchdb/docs/overview.html
> (04:05:36 PM) jan____: that one
>
> In my opinion, it would be a great addition to couchdb. But still, I  
> can't
> wait to use it on my next project.




>
>
>
> On Wed, Nov 26, 2008 at 3:25 PM, Liam Staskawicz <lstask@gmail.com>  
> wrote:
>
>>
>> On Nov 26, 2008, at 12:20 PM, Noah Slater wrote:
>>
>> On Wed, Nov 26, 2008 at 09:57:24AM -0800, Liam Staskawicz wrote:
>>>
>>>> When updating a document, is there any notion of submitting a  
>>>> partial
>>>> update?
>>>> It seems like being able to specify that only some subset of the  
>>>> fields
>>>> in a
>>>> document should be updated would offer some efficiency benefits.   
>>>> I guess
>>>> I
>>>> had in mind some scenario where CouchDB would create the updated  
>>>> record
>>>> by
>>>> merging the existing revision with the new info and saving the  
>>>> updated
>>>> revision, but I'm still new to CouchDB so I don't have a good  
>>>> sense of
>>>> whether
>>>> this tramples on any important concepts.
>>>>
>>>
>>> Nope, CouchDB does not support this at the moment. If you want to  
>>> make an
>>> update
>>> you have to send the entire document each time.
>>>
>>> There is some discussion among CouchDB users and developers about  
>>> the
>>> benefits
>>> of partial updates but it seems the real sticking point so far is  
>>> deciding
>>> on
>>> the mechanism for enabling this. It seems the rough consensus at  
>>> this
>>> point is
>>> that whatever method we use be something that is standardised,  
>>> either
>>> through a
>>> standards body or de facto within the larger JSON community.
>>>
>>
>> Thanks for the response - and yeah, this is not a sticking point at  
>> the
>> moment but as systems start to ramp up this seems like a pretty  
>> good way to
>> make the back and forths much more efficient.   Will be looking  
>> forward to
>> this being introduced at some point.
>>
>> Liam
>>


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