A document that contains the _id of the document created or modified by the insert, replace,
delete, update operations (i.e. CRUD operations). For sharded collections, also displays the full
shard key for the document. The _id field is not repeated if it is already a part of the shard key.
A document that contains the _id of the document created or modified by the insert, replace, delete, update operations (i.e. CRUD operations). For sharded collections, also displays the full shard key for the document. The _id field is not repeated if it is already a part of the shard key.