anchor.diff:                 "doc_count": 3,
                  "sales": {
                     "value": 550
  -               } <1>
  +               }
               },
               {
                  "key_as_string": "2015/02/01 00:00:00",
  
positive.code:                     "sum": {
                          "field": "price"
                      }
                  },
                  "sales_deriv": {
                      "derivative": {
                          "buckets_paths": "sales" <1>
                      }
                  }
              }
          }
      }
  }
  --------------------------------------------------
  
  <1> `bucket_paths` instructs this derivative aggregation to use the output of the `sales` aggregation for the derivative
  
  And the following may be the response:
  
  
negative.code: [[search-aggregations-reducer-max-bucket-aggregation]]
  === Max Bucket Aggregation
  
  A sibling reducer aggregation which identifies the bucket(s) with the maximum value of a specified metric in a sibing aggregation 
  and outputs both the value and the key(s) of the bucket(s). The specified metric must be numeric and the sibling aggregation must 
  be a multi-bucket aggregation.
  
  The following snippet calculates the maximum of the total monthly `sales`:
  
  [source,js]
  --------------------------------------------------
  {
      "aggs" : {
          "sales_per_month" : {
              "date_histogram" : {
                  "field" : "date",
                  "interval" : "month"
  