Map a runtime fieldedit

You map runtime fields by adding a runtime section under the mapping definition and defining a Painless script. This script has access to the entire context of a document, including the original _source and any mapped fields plus their values. At query time, the script runs and generates values for each scripted field that is required for the query.

For example, the script in the following request calculates the day of the week from the @timestamp field, which is defined as a date type. The script calculates the day of the week based on the value of timestamp, and uses emit to return the calculated value.

PUT my-index-000001/
{
  "mappings": {
    "runtime": {
      "day_of_week": {
        "type": "keyword",
        "script": {
          "source": "emit(doc['@timestamp'].value.dayOfWeekEnum.getDisplayName(TextStyle.FULL, Locale.ROOT))"
        }
      }
    },
    "properties": {
      "@timestamp": {"type": "date"}
    }
  }
}

The runtime section can be any of these data types:

  • boolean
  • composite
  • date
  • double
  • geo_point
  • ip
  • keyword
  • long
  • lookup

Runtime fields with a type of date can accept the format parameter exactly as the date field type.

Runtime fields with a type of lookup allow retrieving fields from related indices. See retrieve fields from related indices.

If dynamic field mapping is enabled where the dynamic parameter is set to runtime, new fields are automatically added to the index mapping as runtime fields:

PUT my-index-000001
{
  "mappings": {
    "dynamic": "runtime",
    "properties": {
      "@timestamp": {
        "type": "date"
      }
    }
  }
}

Define runtime fields without a scriptedit

Runtime fields typically include a Painless script that manipulates data in some way. However, there are instances where you might define a runtime field without a script. For example, if you want to retrieve a single field from _source without making changes, you don’t need a script. You can just create a runtime field without a script, such as day_of_week:

PUT my-index-000001/
{
  "mappings": {
    "runtime": {
      "day_of_week": {
        "type": "keyword"
      }
    }
  }
}

When no script is provided, Elasticsearch implicitly looks in _source at query time for a field with the same name as the runtime field, and returns a value if one exists. If a field with the same name doesn’t exist, the response doesn’t include any values for that runtime field.

In most cases, retrieve field values through doc_values whenever possible. Accessing doc_values with a runtime field is faster than retrieving values from _source because of how data is loaded from Lucene.

However, there are cases where retrieving fields from _source is necessary. For example, text fields do not have doc_values available by default, so you have to retrieve values from _source. In other instances, you might choose to disable doc_values on a specific field.

You can alternatively prefix the field you want to retrieve values for with params._source (such as params._source.day_of_week). For simplicity, defining a runtime field in the mapping definition without a script is the recommended option, whenever possible.

Updating and removing runtime fieldsedit

You can update or remove runtime fields at any time. To replace an existing runtime field, add a new runtime field to the mappings with the same name. To remove a runtime field from the mappings, set the value of the runtime field to null:

PUT my-index-000001/_mapping
{
 "runtime": {
   "day_of_week": null
 }
}