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From: Zachary Zolton <zachary.zolton@gmail.com>
Date: Fri, 9 Dec 2011 10:48:59 -0600
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Subject: Re: advice on how to get equal number of items of different types
 from db
To: user@couchdb.apache.org
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Bryan,

The CouchDB way to get back three different types of data would be to
make three view queries. If your problem is that it feels inelegant to
deal with those asynchronous calls, then you should look into an
asynchronous flow control library.

Here are a couple options:

jQuery Deferreds (in 1.5+)
http://www.erichynds.com/jquery/using-deferreds-in-jquery/

Flow-JS
https://github.com/willconant/flow-js


Cheers,

Zach

On Fri, Dec 9, 2011 at 5:42 AM, Rogut=EBs Sparnuotos
<rogutes@googlemail.com> wrote:
> bryan rasmussen (2011-12-09 10:01):
>> Hi,
>>
>> I have a db where items in the db are of different types, lets say
>> type A, B, and C.
>> There are a lot of items in the db, and I am returning 60 at a time in
>> my view. I could theoretically end up in a situation where my first
>> 1000+ results are of type A when what I want =A0is an even mix of type
>> A,B and C.
>>
>> I could of course do a view for each type but this is problematic in
>> that my view is called at the application's load via Ajax, and I don't
>> want to send off 3 requests at that time.
>>
>> So what I want is a view or mapreduce or other Couchdb functionality
>> that allows me to return a mix of my types?
>>
>> Any pointers, suggestions?
>>
>> Thanks,
>> Bryan Rasmussen
>
> I would be more worried about 3 separate views than about 3 requests
> (especially when they are async).
>
> 1. Create one view like
> =A0 =A0 emit([doc.type, doc.sort_criteria], null)
> =A0 and query it like
> =A0 =A0 GET ?startkey=3D["A"]&endkey=3D["A", {}]&limit=3D10
> =A0 =A0 GET ?startkey=3D["B"]&endkey=3D["B", {}]&limit=3D10
> =A0 =A0 GET ?startkey=3D["C"]&endkey=3D["C", {}]&limit=3D10
> 2. Get everything client side and filter through.
> 3. Make your documents help you. For example, if I needed to return a
> =A0 matching triplet of A, B, C, I would keep an index or something:
> =A0 =A0 {"type": "A", "typeindex": 1}
> =A0 =A0 {"type": "B", "typeindex": 1}
> =A0 =A0 {"type": "C", "typeindex": 1}
> =A0 =A0 {"type": "A", "typeindex": 2}
> =A0 and in a view:
> =A0 =A0 emit(doc.typeindex + doc.type, null)
>
> --
> -- =A0Rogut=EBs Sparnuotos