在 Elasticsearch 中获取每个存储桶的平均文档数的最佳方法是什么？

Question

假设我们是帽子制造商并且有一个 Elasticsearch 索引，其中每个文档对应一顶帽子的销售。销售记录的一部分是出售这顶帽子的商店的名称。我想找出每家商店售出的帽子数量，以及所有商店售出的平均帽子数量。我想出的最好方法是这个搜索：

GET hat_sales/_search
{
  "size": 0,
  "query": {"match_all": {}},
  "aggs": {
    "stores": {
      "terms": {
        "field": "storename",
        "size": 65536
      },
      "aggs": {
        "sales_count": {
          "cardinality": {
            "field": "_id"
          }
        }
      }
    },
    "average_sales_count": {
      "avg_bucket": {
        "buckets_path": "stores>sales_count"
      }
    }
  }
}

（旁白： 我将大小设置为 65536，因为这是默认的最大桶数。）

此查询的问题在于 sales_count 聚合执行冗余计算：每个 stores 桶已经有一个 doc_count 属性。但是如何在存储桶路径中访问此 doc_count？

Answer 1

我想这就是你想要的

PUT hat_sales
{
  "mappings": {
    "properties": {
      "storename": {
        "type": "keyword"
      }
    }
  }
}

POST hat_sales/_bulk?refresh=true
{"index": {}}
{"storename": "foo"}
{"index": {}}
{"storename": "foo"}
{"index": {}}
{"storename": "bar"}
{"index": {}}
{"storename": "baz"}
{"index": {}}
{"storename": "baz"}
{"index": {}}
{"storename": "baz"}



GET hat_sales/_search
{
  "size": 0,
  "query": {"match_all": {}},
  "aggs": {
    "stores": {
      "terms": {
        "field": "storename",
        "size": 65536
      }
    },
    "average_sales_count": {
      "avg_bucket": {
        "buckets_path": "stores>_count"
      }
    }
  }
}

到达 _count 的路径是 stores>_count

结果如下：

{
  "took" : 6,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 6,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  },
  "aggregations" : {
    "stores" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "baz",
          "doc_count" : 3
        },
        {
          "key" : "foo",
          "doc_count" : 2
        },
        {
          "key" : "bar",
          "doc_count" : 1
        }
      ]
    },
    "average_sales_count" : {
      "value" : 2.0
    }
  }
}

在 Elasticsearch 中获取每个存储桶的平均文档数的最佳方法是什么？

What is the best way to get the average number of documents per bucket in Elasticsearch?

elasticsearch

elasticsearch-aggregation