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From Jens Alfke <>
Subject Re: Ordered view reduce
Date Fri, 20 Dec 2013 22:50:42 GMT

On Dec 20, 2013, at 2:19 PM, Jens Rantil <> wrote:

> The current implementation only supports basic projections because reduce
> input order is undefined in Couch.

I _think_ that in a standard CouchDB (but not BigCouch) the rows are passed to the reduce
function in ascending key order.

> I've heard of the plugin system. Would
> ordered reduce be something that could be implemented as a plugin?

Well, the ordering is left undefined because of clustered/sharded implementations like BigCouch,
where the documents and index rows can be split across multiple machines. In a setup like
that, I imagine ordered reduce wouldn’t scale well because it would require transferring
index rows between the nodes so that a reduce function running on one node could work on a
contiguous set of rows. So if you had this, you might not want it…

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