You would need to either start with unique user id's or reduce this data twice 
(not sure if couchbase let's you create essentially a "subview" or not)


But basically you'd need to reduce this data to have only 1 row per user/color 
combination (grouping level of 2 with a key of [user, color]) and then reduce 
it again with a simple built in reducer _count using the color as the key. 




--chad

On Fri, Dec 27, 2013 at 11:05 AM, Thomas <[email protected]> wrote:

> Hi,
> I was googling around for a solution of a map/reduce where I will be able 
> to perform a distinct/unique count of user ids, but I wasn't able to find a 
> concrete solution/answer to this topic. My case is to count the unique 
> users per day for example as well as other criteria.
> I have for example the following JSON documents of events:
> {"user":"user1", "color":"blue"}
> {"user":"user1", "color":"blue"}
> {"user":"user1", "color":"red"}
> {"user":"user2", "color":"blue"}
> And with my map/reduce view I want to do the following 
> * number of distinct users per color
> { color: blue, count: 2}
> { color: red, count: 1}
> in SQL terms 
> select color, count(distinct user) as users from test group by color
> Thanks
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