[[mapper-size]]
=== Mapper Size Plugin

The mapper-size plugin provides the `_size` meta field which, when enabled,
indexes the size in bytes of the original
{ref}/mapping-source-field.html[`_source`] field.

:plugin_name: mapper-size
include::install_remove.asciidoc[]

[[mapper-size-usage]]
==== Using the `_size` field

In order to enable the `_size` field, set the mapping as follows:

[source,console]
--------------------------
PUT my-index-000001
{
  "mappings": {
    "_size": {
      "enabled": true
    }
  }
}
--------------------------

The value of the `_size` field is accessible in queries, aggregations, scripts,
and when sorting:

[source,console]
--------------------------
# Example documents
PUT my-index-000001/_doc/1
{
  "text": "This is a document"
}

PUT my-index-000001/_doc/2
{
  "text": "This is another document"
}

GET my-index-000001/_search
{
  "query": {
    "range": {
      "_size": {                      <1>
        "gt": 10
      }
    }
  },
  "aggs": {
    "sizes": {
      "terms": {
        "field": "_size",             <2>
        "size": 10
      }
    }
  },
  "sort": [
    {
      "_size": {                      <3>
        "order": "desc"
      }
    }
  ],
  "script_fields": {
    "size": {
      "script": "doc['_size']"        <4>
    }
  },
  "docvalue_fields": [
    {
      "field": "_size"                <5>
    }
  ]
}
--------------------------
// TEST[continued]

<1> Querying on the `_size` field
<2> Aggregating on the `_size` field
<3> Sorting on the `_size` field
<4> Uses a
{ref}/search-request-body.html#request-body-search-script-fields[script field]
to return the `_size` field in the search response.
<5> Uses a
{ref}/run-a-search.html#docvalue-fields[doc value
field] to return the `_size` field in the search response. Doc value fields are
useful if
{ref}/modules-scripting-security.html#allowed-script-types-setting[inline
scripts are disabled].