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From Paul Davis <>
Subject Re: Multi-Step Map/Reduce?
Date Tue, 31 Mar 2009 02:00:01 GMT
There's been discussion but no implementation as far as I'm aware.
There's definitely quite a bit of interest in both multi-step M/R as
well as merging of indexes a la map/reduce/merge.

As far as I've poked and prodded around the source trying to uncover
an implementation I keep hitting some hard walls in terms of
implementation. Specifically the reduce implementation screws with my
brain quite a bit when trying to contemplate how to derive secondary
views from a view with an attached reduce as I've been trying to not
do something silly like just ignore reduce functions when chaining and

In other words, ideas and patches both welcome. :)

Paul Davis

On Mon, Mar 30, 2009 at 9:48 PM, Zachary Zolton
<> 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.
> Also, I tend to be daft, so I'd appreciate hearing if this idea is
> silly or simply outside of the scope of CouchDB!
> Cheers,
> Zach

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