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From: Damien Katz <damienkatz@gmail.com>
To: couchdb-user@incubator.apache.org
In-Reply-To: <47DE7FA8.6000003@theopenlearningcentre.com>
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Subject: Re: Relying on revisions for rollbacks
Date: Mon, 17 Mar 2008 10:38:49 -0400
References: <1205753351.7678.18.camel@localhost>
 <828B1624-4992-4BE5-ADED-EB252DC88BD8@apache.org>
 <47DE7FA8.6000003@theopenlearningcentre.com>

On Mar 17, 2008, at 10:26 AM, Alan Bell wrote:

> Could the compaction mechanism be rules based? For example it could  
> run a javascript function like a view function passing in the  
> document object and revision id and the function would return true  
> or false depending on whether it is OK to purge that version. I can  
> imagine some use cases where revisions would never be archived,  
> others where revisions might be kept for 6 months, others where the  
> last 5 revisions are kept regardless of age. More complex options  
> might be possible, such as retaining every third revision older than  
> 6 months or in a wiki context purging edits marked as minor.

Possibly.

Right now I want to keep things as simple in concept and  
implementation as possible. Keeping previous revisions as attachments  
will keep the api and database model as simple, perhaps while pushing  
some of the complexity  of managing previous revisions back out to the  
clients. That's ok for now, but if it proves to be unwieldy we can add  
more enhancements later to make things easier.


>
>
> Alan.
>
> Jan Lehnardt wrote:
>> Heya,
>> On Mar 17, 2008, at 7:29 , Shahar Evron wrote:
>>> [...]
>>> As far as I understood, CouchDB does not keep old revisions  
>>> indefinitely
>>> - so if I update a document, it's previous revisions might be  
>>> deleted
>>> after a while.
>>>
>>> Is this true?
>>
>> That is correct. Not at the moment though :) The next release of  
>> CouchDB
>> will include a mechanism called "compaction" that will run  
>> periodically and
>> prune out old revisions.
>>
>> We suggest that you manage old revisions to a document that you want
>> to keep around in attachments to the latest revision.
>>
>> Cheers
>> Jan
>> -- 
>
>
> -- 
> Alan Bell
> The Open Learning Centre
>
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