copy_to（合并参数）

copy_to参数允许你创建自定义的 _all 字段.换句换来说,可以将多个字段的值复制到group field（组字段）,然后可以作为单个字段进行查询.例如, first_name和 last_name可以复制到 full_name字段中,如下所示 :

curl -XPUT 'localhost:9200/my_index?pretty' -H 'Content-Type: application/json' -d'
{
  "mappings": {
    "my_type": {
      "properties": {
        "first_name": {
          "type": "text",
          "copy_to": "full_name"  # 1
        },
        "last_name": {
          "type": "text",
          "copy_to": "full_name"  # 2
        },
        "full_name": {
          "type": "text"
        }
      }
    }
  }
}
'
curl -XPUT 'localhost:9200/my_index/my_type/1?pretty' -H 'Content-Type: application/json' -d'
{
  "first_name": "John",
  "last_name": "Smith"
}
'
curl -XGET 'localhost:9200/my_index/_search?pretty' -H 'Content-Type: application/json' -d'
{
  "query": {
    "match": {
      "full_name": {  # 3
        "query": "John Smith",
        "operator": "and"
      }
    }
  }
}
'

1 , 2	first_name（名字）和 last_name（姓氏）字段复制到full_name 字段.
3	first_name（名字）和last_name（姓氏）字段仍然可以分别查询,full_name可以通过first_name（名字）和last_name（姓氏）来查询.

查看数据

GET /my_index/my_type/_search
{
  "took": 1,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "failed": 0
  },
  "hits": {
    "total": 1,
    "max_score": 1,
    "hits": [
      {
        "_index": "my_index",
        "_type": "my_type",
        "_id": "1",
        "_score": 1,
        "_source": {
          "first_name": "John",
          "last_name": "Smith"
        }
      }
    ]
  }
}

一些要点:

• 复制的是字段值,而不是 term（词条）（由分析过程产生）.

• _source字段不会被修改来显示复制的值.

• 相同的值可以复制到多个字段,通过"copy_to": [ "field_1", "field_2" ] 来操作.