es - elasticsearch - aggs - pipeline - derivative

世界上并没有完美的程序，但是我们并不因此而沮丧，因为写程序就是一个不断追求完美的过程。

问：derivative有什么特点？
答：

问：derivative如何使用？
答：

DELETE /derivative_test

PUT /derivative_test
{
  "mappings": {
    "properties": {
      "type": {"type": "integer"},
      "num": {"type": "integer"},
      "date": {"type": "date"}
    }
  }
}

POST /derivative_test/_bulk
{"index": {"_id": 1}}
{"type": 1, "num": 400, "date": "1989-01-10"}
{"index": {"_id": 2}}
{"type": 2, "num": 450, "date": "1988-01-10"}
{"index": {"_id": 3}}
{"type": 1, "num": 580, "date": "1990-01-10"}
{"index": {"_id": 4}}
{"type": 2, "num": 990, "date": "1990-01-10"}
{"index": {"_id": 5}}
{"type": 1, "num": 660, "date": "1989-01-10"}

# 通过derivative计算增长量
# 通过双重derivative计算增长量的涨幅
# 通过unit计算单位平均变化量
GET /derivative_test/_search
{
  "size": 0,
  "aggs": {
    "derivative_aggs": {
      "date_histogram": {
        "field"            : "date",
        "calendar_interval": "year"
      },
      "aggs": {
        "sum_aggs": {
          "sum": {
            "field": "num"
          }
        },
        "deriva_one_aggs": {
          "derivative": {
            "buckets_path": "sum_aggs",
            "unit": "month"
          }
        },
        "deriva_two_aggs": {
          "derivative": {
            "buckets_path": "deriva_one_aggs",
            "unit": "month"
          }
        }
      }
    }
  }
}

# 结果
{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 5,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "derivative_aggs" : {
      "buckets" : [
        {
          "key_as_string" : "1988-01-01T00:00:00.000Z",
          "key" : 567993600000,
          "doc_count" : 1,
          "sum_aggs" : {
            "value" : 450.0
          }
        },
        {
          "key_as_string" : "1989-01-01T00:00:00.000Z",
          "key" : 599616000000,
          "doc_count" : 2,
          "sum_aggs" : {
            "value" : 1060.0
          },
          "deriva_one_aggs" : {
            "value" : 610.0,
            "normalized_value" : 50.728125
          }
        },
        {
          "key_as_string" : "1990-01-01T00:00:00.000Z",
          "key" : 631152000000,
          "doc_count" : 2,
          "sum_aggs" : {
            "value" : 1570.0
          },
          "deriva_one_aggs" : {
            "value" : 510.0,
            "normalized_value" : 42.52823630136986
          },
          "deriva_two_aggs" : {
            "value" : -100.0,
            "normalized_value" : -8.338869863013699
          }
        }
      ]
    }
  }
}