Metadata fields
OpenSearch provides built-in metadata fields that allow you to access information about the documents in an index. These fields can be used in your queries as needed.
| Metadata field | Description |
|---|---|
_field_names | The document fields with non-empty or non-null values. |
_ignored | The document fields that were ignored during the indexing process due to the presence of malformed data, as specified by the ignore_malformed setting. |
_id | The unique identifier assigned to each document. |
_index | The index in which the document is stored. |
_meta | Stores custom metadata or additional information specific to the application or use case. |
_routing | Allows you to specify a custom value that determines the shard assignment for a document in an OpenSearch cluster. |
_source | Contains the original JSON representation of the document data. |