Count documents of certain type (filter against user before)

Question

Documents (pseudo, rev and id omitted):

{
   "type": 1,
   "username": "aron",
   "data": { ... }
}
{
   "type": 1,
   "username": "bob",
   "data": { ... }
}
{
   "type": 1,
   "username": "steve",
   "data": { ... }
}
{
   "type": 1,
   "username": "steve",
   "data": { ... }
}
{
   "type": 2,
   "username": "steve",
   "data": { ... }
}
{
   "type": 3,
   "username": "steve",
   "data": { ... }
}
{
   "type": 3,
   "username": "steve",
   "data": { ... }
}
{
   "type": 3,
   "username": "steve",
   "data": { ... }
}

I want to know, how many documents of type 1/2/3 steve has.

View:

count: {
    map: function (doc) { 
        emit([doc.username, doc.type], 1);  
    }
    reduce: function (key, values, rereduce) {
        return sum(values);
    }
}

Now I request

/database/_design/myDesign/_view/count?key=["steve",1] // result: 2
/database/_design/myDesign/_view/count?key=["steve",2] // result: 1
/database/_design/myDesign/_view/count?key=["steve",3] // result: 3

This works perfectly well.

To smart things up, I was wondering if I can query that in one view?

Is there a way to count the number of documents of unknown number of types in one view?

Answer 1

You can POST to your view with a body like this;

{"keys":[["steve",1], ["steve",2]]}

Also, try using "_sum" as your reduce function, it will run natively in Erlang and should be several times faster than doing it in Javascript.

Answer 2

You can perform a range query to achieve this:

.../count?startkey=["steve",1]&endkey=["steve",3]&group=true&reduce=true

This will fetch one line for every key between ["steve",1] and ["steve",3] inclusive. You can adjust values 0 and 3 according to what your types can actually be. For instance, if your types can be any scalar value, you can use ["steve",null] and ["steve",{}] as the range boundaries.