arrays - ElasticSearch按数组第一个索引处的NestedObject中的字段排序

Question

我正在尝试在以下文档中对数组的第一个对象内的字段进行排序
每个文档都有一个数组，我想检索按其首个对象排序的文档，然后按城市名称让其命名。在以下结果中，我要首先获取第三个文档，因为城市名称以“L”开头(伦敦')，然后是第二个“M”(“莫斯科”)，然后是第三个“N”(“NYC”)

该结构是以下记录:

具有数组

该数组包含一个对象(称为“地址”)

对象具有一个字段(称为“城市”)

我想按第一个地址对文档进行排序

    get hello/_mapping 
    {
      "hello": {
        "mappings": {
          "jack": {
            "properties": {
              "houses": {
                "type": "nested",
                "properties": {
                  "address": {
                    "properties": {
                      "city": {
                        "type": "text",
                        "fields": {
                          "keyword": {
                            "type": "keyword",
                            "ignore_above": 256
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }

这是我索引的文档

{
  "took": 0,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 3,
    "max_score": 1,
    "hits": [
      {
        "_index": "hello",
        "_type": "jack",
        "_id": "2",
        "_score": 1,
        "_source": {
          "houses": [
            {
              "address": {
                "city": "moscow"
              }
            },
            {
              "address": {
                "city": "belgrade"
              }
            },
            {
              "address": {
                "city": "Sacramento"
              }
            }
          ]
        }
      },
      {
        "_index": "hello",
        "_type": "jack",
        "_id": "1",
        "_score": 1,
        "_source": {
          "houses": [
            {
              "address": {
                "city": "NYC"
              }
            },
            {
              "address": {
                "city": "PARIS"
              }
            },
            {
              "address": {
                "city": "TLV"
              }
            }
          ]
        }
      },
      {
        "_index": "hello",
        "_type": "jack",
        "_id": "3",
        "_score": 1,
        "_source": {
          "houses": [
            {
              "address": {
                "city": "London"
              }
            }
          ]
        }
      }
    ]
  }
}

Answer 1

尝试一下(当然，如果字段可以为空，请在脚本内添加一些测试。请注意，这可能会很慢，因为 flex 不会为该值建立索引。添加一个主地址字段肯定会更快(并且实际上会更快)。成为做到这一点的好方法。

{
      "sort" : {
        "_script" : {
            "script" : "params._source.houses[0].address.city",
            "type" : "string",
            "order" : "asc"
        }
    }
}

您必须使用_source而不是doc [yourfield]，因为您不知道按顺序 flex 存储数组。

编辑:测试字段是否存在

{
  "query": {
    "nested": {
      "path": "houses",
      "query": {
        "bool": {
          "must": [
            {
              "exists": {
                "field": "houses.address"
              }
            }
          ]
        }
      }
    }
  },
  "sort": {
    "_script": {
      "script" : "params._source.houses[0].address.city",
      "type": "string",
      "order": "asc"
    }
  }
}