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 fieldDescription
_field_namesThe document fields with non-empty or non-null values.
_ignoredThe document fields that were ignored during the indexing process due to the presence of malformed data, as specified by the ignore_malformed setting.
_idThe unique identifier assigned to each document.
_indexThe index in which the document is stored.
_metaStores custom metadata or additional information specific to the application or use case.
_routingAllows you to specify a custom value that determines the shard assignment for a document in an OpenSearch cluster.
_sourceContains the original JSON representation of the document data.