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copy_to

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IMPORTANT: This documentation is no longer updated. Refer to Elastic's version policy and the latest documentation.

`copy_to`

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The copy_to parameter allows you to copy the values of multiple fields into a group field, which can then be queried as a single field.

If you often search multiple fields, you can improve search speeds by using copy_to to search fewer fields. See Search as few fields as possible.

For example, the first_name and last_name fields can be copied to the full_name field as follows:

response = client.indices.create(
  index: 'my-index-000001',
  body: {
    mappings: {
      properties: {
        first_name: {
          type: 'text',
          copy_to: 'full_name'
        },
        last_name: {
          type: 'text',
          copy_to: 'full_name'
        },
        full_name: {
          type: 'text'
        }
      }
    }
  }
)
puts response

response = client.index(
  index: 'my-index-000001',
  id: 1,
  body: {
    first_name: 'John',
    last_name: 'Smith'
  }
)
puts response

response = client.search(
  index: 'my-index-000001',
  body: {
    query: {
      match: {
        full_name: {
          query: 'John Smith',
          operator: 'and'
        }
      }
    }
  }
)
puts response

PUT my-index-000001
{
  "mappings": {
    "properties": {
      "first_name": {
        "type": "text",
        "copy_to": "full_name" 
      },
      "last_name": {
        "type": "text",
        "copy_to": "full_name" 
      },
      "full_name": {
        "type": "text"
      }
    }
  }
}

PUT my-index-000001/_doc/1
{
  "first_name": "John",
  "last_name": "Smith"
}

GET my-index-000001/_search
{
  "query": {
    "match": {
      "full_name": { 
        "query": "John Smith",
        "operator": "and"
      }
    }
  }
}

	The values of the `first_name` and `last_name` fields are copied to the `full_name` field.
	The `first_name` and `last_name` fields can still be queried for the first name and last name respectively, but the `full_name` field can be queried for both first and last names.

Some important points:

It is the field value which is copied, not the terms (which result from the analysis process).
The original _source field will not be modified to show the copied values.
The same value can be copied to multiple fields, with "copy_to": [ "field_1", "field_2" ]
You cannot copy recursively via intermediary fields such as a copy_to on field_1 to field_2 and copy_to on field_2 to field_3 expecting indexing into field_1 will eventuate in field_3, instead use copy_to directly to multiple fields from the originating field.
If the target field does not exist in the index mappings, the usual dynamic mapping behavior applies. By default, with dynamic set to true, a non-existent target field will be dynamically added to the index mappings. If dynamic is set to false, the target field will not be added to the index mappings, and the value will not be copied. If dynamic is set to strict, copying to a non-existent field will result in an error.

copy_to is not supported for field types where values take the form of objects, e.g. date_range

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