This reader sends both inserts and updates as inserts. This means that to support replicating Cosmos DB documents the writer must support upsert mode. In upsert mode, a new document (one whose id field does not match that of any existing document) is handled as an insert and an update to an existing documents (based on matching id fields) is handled as an update. For replication, this limits the choice of writers to Cosmos DB Writer and Mongo Cosmos DB Writer. Append-only targets such as files, blobs, and Kafka are also supported so long as they can handle a JSONNodeEvent input stream.