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From Chris Anderson <jch...@apache.org>
Subject Re: [user] Thoughts on document/views...
Date Wed, 11 Feb 2009 21:29:07 GMT
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.

Chris

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

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