public override IEnumerable <Row> Combine(RowSet left, RowSet right, Row outputRow, string[] args) { var _rowList = new RowList(); _rowList.Load(right); // Load the right RowSet into memory foreach (Row leftRow in left.Rows) { leftRow.CopyTo(outputRow); // Copy the data from the leftRow to the output // Copy the data from the rightRow to the output foreach (Row rightRow in _rowList.Rows) { for (int i = 0; i < rightRow.Count; ++i) { rightRow[i].CopyTo(outputRow[i + leftRow.Count]); } yield return(outputRow); } } }