OpenSearch/docs/reference/search/request/docvalue-fields.asciidoc

[[search-request-docvalue-fields]]
=== Doc value Fields

Allows to return the <<doc-values,doc value>> representation of a field for each hit, for
example:

[source,js]
--------------------------------------------------
GET /_search
{
    "query" : {
        "match_all": {}
    },
    "docvalue_fields" : [
        "my_ip_field", <1>
        {
            "field": "my_keyword_field" <2>
        },
        {
            "field": "my_date_field",
            "format": "epoch_millis" <3>
        }
    ]
}
--------------------------------------------------
// CONSOLE
<1> the name of the field
<2> an object notation is supported as well
<3> the object notation allows to specify a custom format

Doc value fields can work on fields that have doc-values enabled, regardless of whether they are stored

`*` can be used as a wild card, for example:

[source,js]
--------------------------------------------------
GET /_search
{
    "query" : {
        "match_all": {}
    },
    "docvalue_fields" : [
        {
            "field": "*_date_field", <1>
            "format": "epoch_millis" <2>
        }
    ]
}
--------------------------------------------------
// CONSOLE
<1> Match all fields ending with `field`
<2> Format to be applied to all matching fields.

Note that if the fields parameter specifies fields without docvalues it will try to load the value from the fielddata cache
causing the terms for that field to be loaded to memory (cached), which will result in more memory consumption.

[float]
==== Custom formats

While most fields do not support custom formats, some of them do:

 - <<date,Date>> fields can take any <<mapping-date-format,date format>>.
 - <<number,Numeric>> fields accept a https://docs.oracle.com/javase/8/docs/api/java/text/DecimalFormat.html[DecimalFormat pattern].

By default fields are formatted based on a sensible configuration that depends
on their mappings: `long`, `double` and other numeric fields are formatted as
numbers, `keyword` fields are formatted as strings, `date` fields are formatted
with the configured `date` format, etc.

NOTE: On its own, `docvalue_fields` cannot be used to load fields in nested
objects -- if a field contains a nested object in its path, then no data will
be returned for that docvalue field. To access nested fields, `docvalue_fields`
must be used within an <<search-request-inner-hits, `inner_hits`>> block.