The mutations to perform. When mode is TRANSACTIONAL, mutations affecting a single entity are applied in order. The following sequences of mutations affecting a single entity are not permitted in a single Commit request: - insert followed by insert - update followed by insert - upsert followed by insert - delete followed by update When mode is NON_TRANSACTIONAL, no two mutations may affect a single entity.

Options for a request.

Options for beginning a new transaction. Transactions can be created explicitly with calls to Datastore.BeginTransaction or implicitly by setting ReadOptions.new_transaction in read requests.