Discard the document; i.e.
Discard the document; i.e. $merge
does not insert the document into the output collection.
Stop and fail the aggregation operation.
Stop and fail the aggregation operation. Any changes to the output collection from previous documents are not reverted.
Insert the document into the output collection.
(Since version ) see corresponding Javadoc for more information.
The behavior of
$merge
if a result document does not match an existing document in the out collection.