//Step 1 :: Index data
DELETE demo

POST demo/product/
{
  "brand": "BrandA",
  "id" : "Pro 005",
  "name": "Meo",
  "barcode" : "000051",
  "unit" : 1
}

POST demo/product/
{
  "brand": "BrandA",
  "id" : "Pro 001",
  "name": "Meo",
  "barcode" : "000052",
  "unit" : 2
}

POST demo/product/
{
  "brand": "BrandA",
  "id" : "Pro 002",
  "name": "Meo",
  "barcode" : "000053",
  "unit" : 3
}


POST demo/product/
{
  "brand": "BrandB",
  "id" : "Pro 006",
  "name": "Meo",
  "barcode" : "000061",
  "unit" : 1
}

POST demo/product/
{
  "brand": "BrandB",
  "id" : "Pro 007",
  "name": "Meo",
  "barcode" : "000062",
  "unit" : 13
}


//Step 2 :: ดึงข้อมูลโดยแบ่งกลุ่มตาม brand และแต่ละกลุ่มเรียงตามจำนวน unit จากมากไปน้อย

GET demo/product/_search?search_type=count
{
  "aggs": {
    "group_by_brand": {
      "terms": {
        "field": "brand",
        "size": 10
      },
      "aggs": {
        "NAME": {
          "top_hits": {
            "_source": [
              "id",
              "barcode",
              "name"
            ],
            "size": 10,
            "sort": [
              {
                "unit": {
                  "order": "desc"
                }
              }
            ]
          }
        }
      }
    }
  }
}


ผลที่ได้ดังนี้

{
   "took": 2,
   "timed_out": false,
   "_shards": {
      "total": 5,
      "successful": 5,
      "failed": 0
   },
   "hits": {
      "total": 5,
      "max_score": 0,
      "hits": []
   },
   "aggregations": {
      "group_by_brand": {
         "doc_count_error_upper_bound": 0,
         "sum_other_doc_count": 0,
         "buckets": [
            {
               "key": "branda",
               "doc_count": 3,
               "NAME": {
                  "hits": {
                     "total": 3,
                     "max_score": null,
                     "hits": [
                        {
                           "_index": "demo",
                           "_type": "product",
                           "_id": "AUzV-9pi8FIkg0OYT-vp",
                           "_score": null,
                           "_source": {
                              "name": "Meo",
                              "id": "Pro 002",
                              "barcode": "000053"
                           },
                           "sort": [
                              3
                           ]
                        },
                        {
                           "_index": "demo",
                           "_type": "product",
                           "_id": "AUzV-8vB8FIkg0OYT-vo",
                           "_score": null,
                           "_source": {
                              "name": "Meo",
                              "id": "Pro 001",
                              "barcode": "000052"
                           },
                           "sort": [
                              2
                           ]
                        },
                        {
                           "_index": "demo",
                           "_type": "product",
                           "_id": "AUzV-8Wc8FIkg0OYT-vn",
                           "_score": null,
                           "_source": {
                              "name": "Meo",
                              "id": "Pro 005",
                              "barcode": "000051"
                           },
                           "sort": [
                              1
                           ]
                        }
                     ]
                  }
               }
            },
            {
               "key": "brandb",
               "doc_count": 2,
               "NAME": {
                  "hits": {
                     "total": 2,
                     "max_score": null,
                     "hits": [
                        {
                           "_index": "demo",
                           "_type": "product",
                           "_id": "AUzV--eT8FIkg0OYT-vr",
                           "_score": null,
                           "_source": {
                              "name": "Meo",
                              "id": "Pro 007",
                              "barcode": "000062"
                           },
                           "sort": [
                              13
                           ]
                        },
                        {
                           "_index": "demo",
                           "_type": "product",
                           "_id": "AUzV--KM8FIkg0OYT-vq",
                           "_score": null,
                           "_source": {
                              "name": "Meo",
                              "id": "Pro 006",
                              "barcode": "000061"
                           },
                           "sort": [
                              1
                           ]
                        }
                     ]
                  }
               }
            }
         ]
      }
   }
}