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From Robert Newson <robert.new...@gmail.com>
Subject Re: iterative map reduce
Date Wed, 14 Dec 2011 09:05:22 GMT
Chained map-reduce is not available in the open source BigCouch
project, only on our hosted service at cloudant.com. Sorry!

B.

On 14 December 2011 09:01, Alon Keren <alon.keren@gmail.com> wrote:
> I've been working on an open-source tool with a similar approach chaining
> map-reduce:
> https://github.com/afters/Couch-Incarnate
>
> The need to pay the bills withheld me from putting more time into it
> lately, so I can't say it's production quality.
> Hopefully, this will change soon.
>
> Dominic - the method I currently use in production is to poll the changes
> on my DB every few seconds and update a 'summary' DB accordingly. It's not
> pretty, but it works. I hope to replace it with Couch-Incarnate asap.
>
>  Alon
>
> On 14 December 2011 10:50, Dave Cottlehuber <dave@muse.net.nz> wrote:
>
>> On 14 December 2011 05:46, Dominic Tarr <dominic.tarr@gmail.com> wrote:
>> > hi,
>> >
>> > I need a iterative map reduce, prefurably, in couchdb.
>> >
>> > I want to be able to do a map reduce to generate unique items, then
>> another
>> > map reduce to generate stats about those unique items.
>> >
>> > from what I know about couchdb at the moment, it seems like id have to do
>> > the first step at the document creation step, which is just ugly.
>> >https://mail.google.com/mail/?shva=1#inbox
>> > has anyone else dealt with this problem?
>>
>> Hi Dom,
>>
>> Cloudant do this in BigCouch which they released as open source a
>> while back http://support.cloudant.com/kb/views/chained-mapreduce-views
>> there are a few other posts on chained MR around but I don't know of a
>> better Couch-style implementation. Their basic approach is to copy the
>> view output into a new db which you'd then re-MR as required. Rinse
>> and repeat until complete.
>>
>> Depending on your data it might be possible to implement their
>> view->copy to db -> new view approach yourself in native couch. It
>> would be interesting to do this as a couch extension using that nifty
>> plugin interface that hasn't been developed yet!
>>
>> A+
>> Dave
>>

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