mongoc_client_set_write_concern()

void
mongoc_client_set_write_concern (mongoc_client_t              *client,
                                 const mongoc_write_concern_t *write_concern);

Sets the write concern for the client. This only affects future operations, collections, and databases inheriting from client.

The default write concern is MONGOC_WRITE_CONCERN_W_DEFAULT: the driver blocks awaiting basic acknowledgment of write operations from MongoDB. This is the correct write concern for the great majority of applications.