Metadata fields

Each document has metadata associated with it, such as the _index, mapping _type, and _id metadata fields. The behavior of some of these metadata fields can be customized when a mapping type is created.

Identity metadata fields

_index

The index to which the document belongs.

_type

The document’s mapping type.

_id

The document’s ID.

Document source metadata fields

_source

The original JSON representing the body of the document.

_size

The size of the _source field in bytes, provided by the mapper-size plugin.

Indexing metadata fields

_field_names

All fields in the document which contain non-null values.

_ignored

All fields in the document that have been ignored at index time because of ignore_malformed.

Routing metadata field

_routing

A custom routing value which routes a document to a particular shard.

Other metadata field

_meta

Application specific metadata.