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From Damien Katz <dam...@apache.org>
Subject Re: [user] Thoughts on document/views...
Date Wed, 11 Feb 2009 21:45:34 GMT

On Feb 11, 2009, at 4:29 PM, Chris Anderson wrote:

> On Wed, Feb 11, 2009 at 10:28 AM, Wout Mertens <wmertens@cisco.com>  
> wrote:
>> On Feb 11, 2009, at 7:22 PM, kowsik wrote:
>>
>>>
>>> What I'm getting at is, does it make sense to have some type of
>>> document "class" attribute and then have views bound to these  
>>> classes?
>>> The goal, of course, being that couch-db can pre-filter a lot of  
>>> these
>>> things and only run the views for the appropriate types of  
>>> documents.
>>
>> I'm probably speaking before my turn being such a newbie, but why  
>> wouldn't
>> you create a new database for disjoint classes of documents?
>
> That's the basic rule of thumb: Document only need to be in the same
> database with each other, if they need to be run through the same
> views (or they need to be replicated together).
>
> If you have a db with millions of records, but only a handful of them
> are interesting to to your views, you will save a lot of serialization
> by putting the viewed documents in their own database.
>
>>
>> Also, once a view is run on a document, it doesn't get re-run that  
>> often
>> does it?
>
> Views are run one per document update, so if you write the document
> once, it only gets run through the view server once.
>
> If you have say, 5 different document "classes" and you have views
> that care about each of them, if you put those views in the same
> design document, then you will not have extra serialization hits. Each
> document update is sent to the view server once per design document.
>
>>
>> So other than eating diskspace, maybe there's not really anything  
>> wrong with
>> keeping everything in one db.
>
> My recommendation is to not worry about it, unless you have like 75%
> or more docs that don't show up in any view. In that case, those docs
> might better off in another database.

I agree with Chris. The way view indexes are updated en-masse, it  
makes this mostly a non-issue.

-Damien

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