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From Will Schenk <wsch...@gmail.com>
Subject Re: 3 Newbie questions
Date Thu, 25 Sep 2008 15:35:48 GMT
On 2008-09-25 10:17:16 -0400, Adam Kocoloski 
<adam.kocoloski@gmail.com> said:
> 
> You should be able to get the latest revision without a reduce  
> (generally a good thing to avoid if you can).  Something like
> 
> function(doc) {
>    if( doc.class == "RemoteUrl" && doc.content ) {
>      emit([doc.normalized_url, doc.created_at], doc);
>    }
> }
> 
> will give you all your documents sorted first by URL and then by  
> revision time.  Then you can query the view with some combination of  
> startkey, count, and maybe descending=true (depending on how your  
> revision dates sort) to get the latest revision of a particular doc.   
> Alternatively, if you wanted to suppress all old revisions in the view  
> you could add a simpler reduce function which takes advantage of the  
> map sorting the results for you:
> 
> function(keys, values) {
>    return values[0]; // or maybe values.pop();
> }

thats interesting... I didn't realize that what got passed back to the 
reduce function was sorted.  My instinct is to make queries return what 
i want and not put logic in the app, if only to limit the amount of 
data moved over the wire.
> 
> If you don't need to analyze the bulk-data in any view you could  
> consider storing it as an attachment to a doc.  Details are at the  
> bottom of this page:
> 
> http://wiki.apache.org/couchdb/HttpDocumentApi

I missed this whole thing of an attachment!  I'll be doing the analysis 
on the ruby side, so I just need the DB to manage the data, not 
transform it at all.

> 
> Yeah, I guess that's a bit tricky.  If the data volume doesn't get in  
> your way you could emit [places.lat, places.long] as the key, query  
> the view with your latitude range as startkey and endkey, and then  
> pick out documents in your longitude range client-side.  Others may  
> well have more clever suggestions.  Best,

Ug.

Thanks for the prompt reply.

-w



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