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From "Chris Anderson" <jch...@apache.org>
Subject Re: partial/diff updates?
Date Thu, 27 Nov 2008 01:32:34 GMT
diffs - if we can get the transport right, they'd make a great use case.

The problem, as has been discussed in the archives, is a canonical
json format, or a json diff format, neither of which are obvious to
implement.

for attachments, binary diffs would be interesting, I wonder how
usable git's format would be for us?

On Wed, Nov 26, 2008 at 5:14 PM, Jan Lehnardt <jan@apache.org> wrote:
>
> 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
>>>
>
>



-- 
Chris Anderson
http://jchris.mfdz.com

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