如何通过Elasticsearch中的嵌套字段计算多个唯一文档?

2019年11月15日 38点热度 0条评论

我正在尝试计算具有唯一嵌套字段值的文档(以及文档本身)。看起来获得唯一文档有效。
但是,当我尝试执行count的请求时,出现如下错误:

Suppressed: org.elasticsearch.client.ResponseException: method [POST], host [http://localhost:9200], URI [/package/_count?ignore_throttled=true&ignore_unavailable=false&expand_wildcards=open&allow_no_indices=true], status line [HTTP/1.1 400 Bad Request] {"error":{"root_cause":[{"type":"parsing_exception","reason":"request does not support [collapse]","line":1,"col":216}],"type":"parsing_exception","reason":"request does not support [collapse]","line":1,"col":216},"status":400}

编码:

        BoolQueryBuilder innerTemplNestedBuilder = QueryBuilders.boolQuery();
        NestedQueryBuilder templatesNestedQuery = QueryBuilders.nestedQuery("attachment", innerTemplNestedBuilder, ScoreMode.None);
        BoolQueryBuilder mainQueryBuilder = QueryBuilders.boolQuery().must(templatesNestedQuery);
        if (!isEmpty(templateName)) {
            innerTemplNestedBuilder.filter(QueryBuilders.termQuery("attachment.name", templateName));
        }
        SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.searchSource()
                    .collapse(new CollapseBuilder("attachment.uuid"))
                    .query(mainQueryBuilder);
    // NEXT LINE CAUSE ERROR
        long count = client.count(new CountRequest("package").source(searchSourceBuilder), RequestOptions.DEFAULT).getCount(); <<<<<<<<<< ERROR HERE
        // THIS WORKS 
        SearchResponse searchResponse = client.search(
                    new SearchRequest(
                            new String[] {"package"},
                            searchSourceBuilder.timeout(new TimeValue(20, TimeUnit.SECONDS)).from(offset).size(limit)
                    ).indices("package").searchType(SearchType.DFS_QUERY_THEN_FETCH),
                    RequestOptions.DEFAULT
        );
        return ....;

该方法的总体目的是获取一部分文档以及所有此类文档的数量。可能已经有另一种方法可以满足这种需求。如果我尝试使用
count
aggregations获取
cardinality-我得到的结果为零,它似乎不适用于嵌套字段。

计数要求:

{
    "query": {
        "bool": {
            "must": [
                {
                    "nested": {
                        "query": {
                            "bool": {
                                "adjust_pure_negative": true,
                                "boost": 1.0
                            }
                        },
                        "path": "attachment",
                        "ignore_unmapped": false,
                        "score_mode": "none",
                        "boost": 1.0
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1.0
        }
    },
    "collapse": {
        "field": "attachment.uuid"
    }
}

如何创建映射:

curl -X DELETE "localhost:9200/package?pretty"
curl -X PUT    "localhost:9200/package?include_type_name=true&pretty" -H 'Content-Type: application/json' -d '{
    "settings" :  {
        "number_of_shards" : 1,
        "number_of_replicas" : 1
    }}'
curl -X PUT    "localhost:9200/package/_mappings?pretty" -H 'Content-Type: application/json' -d'
{
      "dynamic": false,
      "properties" : {
        "attachment": {
            "type": "nested",
            "properties": {
                "uuid" : { "type" : "keyword" },
                "name" : { "type" : "text" }
            }
        },
        "uuid" : {
          "type" : "keyword"
        }
      }
}
'

代码生成的结果查询应如下所示:

curl -X POST "localhost:9200/package/_count?&pretty" -H 'Content-Type: application/json' -d' { "query" :
    {
        "bool": {
            "must": [
                {
                    "nested": {
                        "query": {
                            "bool": {
                                "adjust_pure_negative": true,
                                "boost": 1.0
                            }
                        },
                        "path": "attachment",
                        "ignore_unmapped": false,
                        "score_mode": "none",
                        "boost": 1.0
                    }
                }
            ],
            "adjust_pure_negative": true,
            "boost": 1.0
        }
    },
    "collapse": {
        "field": "attachment.uuid"
    }
}'

解决方案如下:

可以在_search上下文中折叠only be used,而不是在_count中折叠。

其次,您的查询甚至可以做什么?您那里有很多冗余参数,例如boost:1等。您不妨说:

POST /package/_count?&pretty
{
  "query": {
    "bool": {
      "must": [
        {
          "nested": {
            "path": "attachment",
            "query": {
              "match_all": {}
            }
          }
        }
      ]
    }
  }
}

这实际上什么也没做:)

要回答您的原始问题,即“对具有唯一嵌套字段值的文档进行计数”,

假设有3个文档,其中2个具有相同的
attachment.uuid值:

[
  {
    "attachment":{
      "uuid":"04144e14-62c3-11ea-bc55-0242ac130003"
    }
  },
  {
    "attachment":{
      "uuid":"04144e14-62c3-11ea-bc55-0242ac130003"
    }
  },
  {
    "attachment":{
      "uuid":"100b9632-62c3-11ea-bc55-0242ac130003"
    }
  }
]

要获取
terms
uuid分类,请运行

GET package/_search
{
  "size": 0,
  "aggs": {
    "nested_uniques": {
      "nested": {
        "path": "attachment"
      },
      "aggs": {
        "subagg": {
          "terms": {
            "field": "attachment.uuid"
          }
        }
      }
    }
  }
}

产生

...
{
  "aggregations":{
    "nested_uniques":{
      "doc_count":3,
      "subagg":{
        "doc_count_error_upper_bound":0,
        "sum_other_doc_count":0,
        "buckets":[
          {
            "key":"04144e14-62c3-11ea-bc55-0242ac130003",
            "doc_count":2
          },
          {
            "key":"100b9632-62c3-11ea-bc55-0242ac130003",
            "doc_count":1
          }
        ]
      }
    }
  }
}

为了获得唯一嵌套字段的父文档数,我们将不得不变得更加聪明:

GET package/_search
{
  "size": 0,
  "aggs": {
    "nested_uniques": {
      "nested": {
        "path": "attachment"
      },
      "aggs": {
        "scripted_uniques": {
          "scripted_metric": {
            "init_script": "state.my_map = [:];",
            "map_script": """
              if (doc.containsKey('attachment.uuid')) {
                state.my_map[doc['attachment.uuid'].value.toString()] = 1;
              }
            """,
            "combine_script": """
              def sum = 0;
              for (c in state.my_map.entrySet()) {
                sum += 1
              }
              return sum
            """,
            "reduce_script": """
              def sum = 0;
              for (agg in states) {
                sum += agg;
              }
              return sum;
            """
          }
        }
      }
    }
  }
}

哪个返回

...
{
  "aggregations":{
    "nested_uniques":{
      "doc_count":3,
      "scripted_uniques":{
        "value":2
      }
    }
  }
}

而这个
scripted_uniques: 2正是您所追求的。

注意:我使用嵌套的脚本指标aggs解决了这个用例,但是如果您知道有一种更清洁的方法,我非常乐于学习它!