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From Chris Anderson <jch...@apache.org>
Subject Re: Multi-Step Map/Reduce?
Date Tue, 31 Mar 2009 04:17:35 GMT
On Mon, Mar 30, 2009 at 9:07 PM, Chris Anderson <jchris@apache.org> wrote:
> On Mon, Mar 30, 2009 at 8:50 PM, Zachary Zolton
> <zachary.zolton@gmail.com> wrote:
>> @jchris is that similar to what you meant?
>>
>
> Pretty much. Go for it!

The difference between those two is that mine (group_level reduce
mirrored to a new db) allows you to do stuff that spans multiple
document depending on key range. Just adding a transform to
replication would only give you one doc at a time.

I implemented group=true reduce to another db in Ruby here:
http://github.com/jchris/couchrest/blob/master/lib/couchrest/helper/pager.rb

>
>> On Mon, Mar 30, 2009 at 10:49 PM, Zachary Zolton
>> <zachary.zolton@gmail.com> wrote:
>>> I've been thinking, if there was just a reasonable way to replicate
>>> another database with the output of a view, then you could just write
>>> regular one-pass map/reduce views on the "derived" database.
>>>
>>> That would seem to cause fewer ripples across the codebase.
>>>
>>> On Mon, Mar 30, 2009 at 10:40 PM, Chris Anderson <jchris@apache.org> wrote:
>>>> On Mon, Mar 30, 2009 at 6:48 PM, Zachary Zolton
>>>> <zachary.zolton@gmail.com> wrote:
>>>>> Devs,
>>>>>
>>>>> Has there been any discussion of using multiple rounds of map/reduce
>>>>> for CouchDB views?
>>>>>
>>>>> If were possible, and the view could be indexed within acceptable
>>>>> bounds of memory and processing time, I could see using it situations
>>>>> where the current one-pass solution proves difficult or requires
>>>>> multiple queries.
>>>>
>>>> I think the simplest way to add value would be to make a way to bounce
>>>> a group_level reduce query to documents in another database. Then you
>>>> could use views to sort them by value etc.
>>>>
>>>>>
>>>>> Also, I tend to be daft, so I'd appreciate hearing if this idea is
>>>>> silly or simply outside of the scope of CouchDB!
>>>>>
>>>>
>>>>
>>>> I think it sounds great.
>>>>
>>>> Chris
>>>>
>>>> --
>>>> Chris Anderson
>>>> http://jchrisa.net
>>>> http://couch.io
>>>>
>>>
>>
>
>
>
> --
> Chris Anderson
> http://jchrisa.net
> http://couch.io
>



-- 
Chris Anderson
http://jchrisa.net
http://couch.io

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