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From Dan <>
Subject Re: partial/diff updates?
Date Wed, 26 Nov 2008 20:40:50 GMT
Here is a conversation I had on the IRC channel #couchdb on this subject on
november 24, 2008 (2 days ago). Hope this helps!

(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
(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____:
(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 <> 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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