select_sample.js

// design view
{
   "_id": "_design/select",
   "_rev": "13-d3471506dd8836f5438a6af58b7f4ee4",
   "language": "javascript",
   "views": {
       "all": {
           "map": "function (doc) { if (doc.type == \"car\") { emit(null, null);} }"
       },
       "count": {
           "map": "function (doc) { emit(null, 1); }",
           "reduce": "function (keys, values ,rr) { return sum(values); }"
       },
       "by_maker": {
           "map": "function (doc) { emit(doc.maker, null); }"
       },
       "by_maker_group_model": {
           "map": "function (doc) { emit([doc.maker, doc.model], 1); }",
           "reduce": "function (keys, values ,rr) { return sum(values); }"
       }
   }
}
// dataとしては下記の感じ
{
    "type":"car",
    "maker":"AMG",
    "model":"C65",
    "year":2009,
    "price":10200000
}

{
    "type":"car", 
    "maker":"BMW",
    "model":"M3",
    "year":2009,
    "price":10200000
}

{
    "type":"car",
    "maker":"AMG",
    "model":"E55",
    "year":2007,
    "price":12200000
}