ES7.16.2基础操作之cardinality去重及性能优化（十六）

## cardinality:每个月销售品牌去重统计
## precision_threshold优化准确率和内存开销
## HyperLogLog++(HLL)算法性能优化
GET tvs/_search
{
  "size": 0,
  "aggs": {
    "months": {
      "date_histogram": {
        "field": "sold_date",
        "interval": "month"
      },
      "aggs": {
        "distinct_brand": {
          "cardinality": {
            "field": "brand",
            "precision_threshold": 100
          }
        }
      }
    }
  }
}