﻿---
title: fields
description: It is often useful to index the same field in different ways for different purposes. This is the purpose of multi-fields. For instance, a string field...
url: https://www.elastic.co/elastic/docs-builder/docs/2437/reference/elasticsearch/mapping-reference/multi-fields
---

# fields
It is often useful to index the same field in different ways for different purposes. This is the purpose of *multi-fields*. For instance, a `string` field could be mapped as a `text` field for full-text search, and as a `keyword` field for sorting or aggregations:
```json

{
  "mappings": {
    "properties": {
      "city": {
        "type": "text",
        "fields": {
          "raw": { <1>
            "type":  "keyword"
          }
        }
      }
    }
  }
}


{
  "city": "New York"
}


{
  "city": "York"
}


{
  "query": {
    "match": {
      "city": "york" <2>
    }
  },
  "sort": {
    "city.raw": "asc" <3>
  },
  "aggs": {
    "Cities": {
      "terms": {
        "field": "city.raw" <3>
      }
    }
  }
}
```

You can add multi-fields to an existing field using the [update mapping API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-indices-put-mapping).
<warning>
  If an index (or data stream) contains documents when you add a multi-field, those documents will not have values for the new multi-field. You can populate the new multi-field with the [update by query API](https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-update-by-query).
</warning>

A multi-field mapping is completely separate from the parent field’s mapping. A multi-field doesn’t inherit any mapping options from its parent field. Multi-fields don’t change the original `_source` field.

## Multi-fields with multiple analyzers

Another use case of multi-fields is to analyze the same field in different ways for better relevance. For instance we could index a field with the [`standard` analyzer](https://www.elastic.co/elastic/docs-builder/docs/2437/reference/text-analysis/analysis-standard-analyzer) which breaks text up into words, and again with the [`english` analyzer](/elastic/docs-builder/docs/2437/reference/text-analysis/analysis-lang-analyzer#english-analyzer) which stems words into their root form:
```json

{
  "mappings": {
    "properties": {
      "text": { <1>
        "type": "text",
        "fields": {
          "english": { <2>
            "type":     "text",
            "analyzer": "english"
          }
        }
      }
    }
  }
}


{ "text": "quick brown fox" } <3>


{ "text": "quick brown foxes" } <3>


{
  "query": {
    "multi_match": {
      "query": "quick brown foxes",
      "fields": [ <4>
        "text",
        "text.english"
      ],
      "type": "most_fields" <4>
    }
  }
}
```

The `text` field contains the term `fox` in the first document and `foxes` in the second document. The `text.english` field contains `fox` for both documents, because `foxes` is stemmed to `fox`.
The query string is also analyzed by the `standard` analyzer for the `text` field, and by the `english` analyzer for the `text.english` field. The stemmed field allows a query for `foxes` to also match the document containing just `fox`. This allows us to match as many documents as possible. By also querying the unstemmed `text` field, we improve the relevance score of the document which matches `foxes` exactly.