OpenSearch/docs/reference/mapping/params/store.asciidoc

[[mapping-store]]
=== `store`

By default, field values are <<mapping-index,indexed>> to make them searchable,
but they are not _stored_.  This means that the field can be queried, but the
original field value cannot be retrieved.

Usually this doesn't matter.  The field value is already part of the
<<mapping-source-field,`_source` field>>, which is stored by default. If you
only want to retrieve the value of a single field or of a few fields, instead
of the whole `_source`, then this can be achieved with
<<search-request-source-filtering,source filtering>>.

In certain situations it can make sense to `store` a field.  For instance, if
you have a document with a `title`, a `date`, and a very large `content`
field, you may want to retrieve just the `title` and the `date` without having
to extract those fields from a large `_source` field:

[source,js]
--------------------------------------------------
PUT /my_index
{
  "mappings": {
    "my_type": {
      "properties": {
        "title": {
          "type": "string",
          "store": true <1>
        },
        "date": {
          "type": "date",
          "store": true <1>
        },
        "content": {
          "type": "string"
        }
      }
    }
  }
}

PUT /my_index/my_type/1
{
  "title":   "Some short title",
  "date":    "2015-01-01",
  "content": "A very long content field..."
}

GET my_index/_search
{
  "fields": [ "title", "date" ] <2>
}
--------------------------------------------------
// AUTOSENSE
<1> The `title` and `date` fields are stored.
<2> This request will retrieve the values of the `title` and `date` fields.

[NOTE]
.Stored fields returned as arrays
======================================

For consistency, stored fields are always returned as an _array_ because there
is no way of knowing if the original field value was a single value, multiple
values, or an empty array.

If you need the original value, you should retrieve it from the `_source`
field instead.

======================================

Another situation where it can make sense to make a field stored is for those
that don't appear in the `_source` field (such as <<copy-to,`copy_to` fields>>).