Writing a simple group by with map-reduce (Couchbase) - mapreduce

Question

I'm new to the whole map-reduce concept, and i'm trying to perform a simple map-reduce function.
I'm currently working with Couchbase server as my NoSQL db.
I want to get a list of all my types:
key: 1, value: null
key: 2, value: null
key: 3, value: null
Here are my documents:
{
"type": "1",
"value": "1"
}
{
"type": "2",
"value": "2"
}
{
"type": "3",
"value": "3"
}
{
"type": "1",
"value": "4"
}
What I've been trying to do is:
Write a map function:
function (doc, meta) {
emit(doc.type, 0);
}
Using built-in reduce function:
_count
But i'm not getting the expected result.
How can I get all types ?
UPDATE
Please notice that the types are different documents, and I know that reduce works on a document and doesn't executes outside of it.

Answer 1

By default it will reduce all key groups. The feature you want is called group_level:
This is equivalent of reduce=true
~ $ curl 'http://localhost:8092/so/_design/dev_test/_view/test?group_level=0'
{"rows":[
{"key":null,"value":4}
]
}
But here is how you can get reduction by the first level of the key
~ $ curl 'http://localhost:8092/so/_design/dev_test/_view/test?group_level=1'
{"rows":[
{"key":"1","value":2},
{"key":"2","value":1},
{"key":"3","value":1}
]
}
There is also blog post about this: http://blog.couchbase.com/understanding-grouplevel-view-queries-compound-keys
There is appropriate option in couchbase admin console: