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From: Wout Mertens <wout.mertens@gmail.com>
To: user@couchdb.apache.org
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Subject: Re: equivalent of JOINs in couchdb?
Date: Tue, 17 Mar 2009 08:08:42 +0100
References: <41139fcb0903130459td4f3d40ic4f418d7842c14ba@mail.gmail.com>
 <094453DE-AFFD-4905-A2F3-4A35304BC1FA@apache.org>
 <41139fcb0903162334x29642057q949366f1c1add446@mail.gmail.com>

On Mar 17, 2009, at 7:34 AM, Anand Chitipothu wrote:

>> http://www.cmlenz.net/archives/2007/10/couchdb-joins
>>
>
> Thanks. That was a good article.
>
> For my understanding, let me extend the same example to a magazine
> instead of blog.
> A magazine will have issues, each issue will have posts and post will
> have comments.
> I can use the technique described in the above blog post to display
> comments in each post.
>
> What if I want to display all comments of all posts of an issue?


Something like

function(doc) {
    if (doc.type == "post") {
       map([doc.magazine, doc._id, 1], doc);
    } else if (doc.type == "comment") {
       map([doc.magazine, doc.post, 2], doc);
    }
}

? You'd need to duplicate the magazine information on the comments  
though.

Wout.