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From Kurt Mackey <k...@mubble.net>
Subject Re: Selectively keeping revisions around
Date Wed, 23 Jul 2008 00:46:24 GMT
Doh!  That makes sense, but it's still sad. :)


On Jul 22, 2008, at 3:50 PM, Jan Lehnardt wrote:

>
> On Jul 22, 2008, at 19:22 , Kurt Mackey wrote:
>
>> I'm admittedly pretty new to CouchDB, but I'm having a tough time
>> figuring out how to use the document revisions it keeps around.  As
>> I understand it, PUTs replace what's there, leaving what's there in
>> a deleted state until you compact the database, at which point it
>> goes away forever.
>>
>> So given that (and correct me if I got it wrong), what's the best
>> way of keeping revisions around forever?  I have a number of
>> documents that will be changed quite frequently, and I'd like to get
>> at their history, provide diffs against it, etc.  Is anyone doing
>> this?
>
> Sorry to disappoint you.
>
> Do not rely on the revisions for what you want to do.
> Only go with the no-compaction route if you have
> very little data.
>
> To keep documents around you can do two things:
>   1) Save old revisions as attachments to the most
> recent revision.
>   2) Save old revisions as new documents.
>
> Both come with advantages and disadvantages and
> both seem clumsy in the light of possibly using the
> built in revision system. We'd like to have the revision
> system work as you want to use it, but getting it right
> with the distributed replication is kinda tricky, so we
> don't do that as of yet and you should not rely on it.
>
> 1) Advantages
> All data is available under a single doc id.
>
> 1) Disadvantages
> You need to copy around revisions manually.
> Can't use the structure of your old revisions in views.
>
> 2) Advantages
> You can use your old revisions in views.
> You can use view to collect a doc and all revisions
> (see http://www.cmlenz.net/archives/2007/10/couchdb-joins)
>
> 2) Disadvantages
> Data is spread over multiple doc ids.
>
> (There might be more, I'm kinda short on time at the moment,
> fill in the blanks please :)
>
> Cheers
> Jan
> --
>


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