You may find this article useful.
http://www.cmlenz.net/archives/2007/10/couchdb-joins

On Fri, Jun 25, 2010 at 7:21 PM, Sean Coates <[email protected]> wrote:
> ("subquery" for lack of a better term)
>
> Hello.
>
> I asked this in #CouchDB, but Jan suggested I also email it here.
>
> I have a problem where I have data in couch, and I want to perform what seems 
> like one too many leaps of logic from within a view. Here's some sample data:
>
> [
> {"_id":1,"_rev":1,"type":"user","following":[2,3]},
> {"_id":2,"_rev":1,"type":"user","following":[1]},
> {"_id":3,"_rev":1,"type":"user","following":[1]},
> {"_id":4,"_rev":1,"type":"asset","ownerid":1},
> {"_id":5,"_rev":1,"type":"asset","ownerid":1},
> {"_id":6,"_rev":1,"type":"asset","ownerid":2},
> {"_id":7,"_rev":1,"type":"asset","ownerid":3},
> {"_id":8,"_rev":1,"type":"asset","ownerid":3}
> ]
> I want to query for a given id where type=user, and get all type=asset 
> records owned by that user, or by users that the queried user is following. 
> Here are some examples that hopefully help:
>
> _id=1; want documents with IDs: [4,5,6,7,8]
> _id=2; want documents with IDs: [4,5,6]
> _id=3; want documents with IDs: [4,5,7,8]
> I hope that's clear enough. if not, please let me know, and I'll try to 
> expand my explanation.
>
> The foundation of the problem seems to be that from within a map, I can't 
> fetch secondary type=user documents in order to perform what amounts to a 
> join (in SQL-speak).
>
> Any help is appreciated. I'm currently solving this problem on the app side, 
> but that's far from ideal (causes a mess with things like limits, for 
> example).
>
> S
>
>



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