protected override async Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehavior behavior, CancellationToken cancellationToken) {
cancellationToken.ThrowIfCancellationRequested();
cancellationToken.Register(Cancel);
var reader = new BigQueryDataReader(behavior, this, Connection.Service);
await reader.InitializeAsync(cancellationToken).ConfigureAwait(false);
return reader;
}