OpenSearch/docs/reference/mapping/fields/analyzer-field.asciidoc

[[mapping-analyzer-field]]
=== `_analyzer`

The `_analyzer` mapping allows to use a document field property as the
name of the analyzer that will be used to index the document. The
analyzer will be used for any field that does not explicitly defines an
`analyzer` or `index_analyzer` when indexing.

Here is a simple mapping:

[source,js]
--------------------------------------------------
{
    "type1" : {
        "_analyzer" : {
            "path" : "my_field"
        }
    }
}
--------------------------------------------------

The above will use the value of the `my_field` to lookup an analyzer
registered under it. For example, indexing the following doc:

[source,js]
--------------------------------------------------
{
    "my_field" : "whitespace"
}
--------------------------------------------------

Will cause the `whitespace` analyzer to be used as the index analyzer
for all fields without explicit analyzer setting.

The default path value is `_analyzer`, so the analyzer can be driven for
a specific document by setting the `_analyzer` field in it. If a custom json
field name is needed, an explicit mapping with a different path should
be set.

By default, the `_analyzer` field is indexed, it can be disabled by
settings `index` to `no` in the mapping.