Metadata fieldsedit

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

Identity metadata fieldsedit

_index

The index to which the document belongs.

_id

The document’s ID.

Document source metadata fieldsedit

_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 fieldsedit

_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 fieldedit

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

Other metadata fieldedit

_meta
Application specific metadata.