Using OpenXml to copy large Excel file - Append data to same file

Hi .

I am trying to use Open XML to copy data from multiple datatables ( around 30+ datatables) . Each datatable contains 10000 rows and 255 columns .

I have tried multiple approach but, I am get the error of Memory Exception.

 private void ExportDataTable(DataTable table, string destination)
        {
            try
            {                

                using (var workbook = SpreadsheetDocument.Create(destination, DocumentFormat.OpenXml.SpreadsheetDocumentType.Workbook))
                {
                    var workbookPart = workbook.AddWorkbookPart();
                    workbook.WorkbookPart.Workbook = new DocumentFormat.OpenXml.Spreadsheet.Workbook();
                    workbook.WorkbookPart.Workbook.Sheets = new DocumentFormat.OpenXml.Spreadsheet.Sheets();

                    uint sheetId = 1;

                                 var sheetPart = workbook.WorkbookPart.AddNewPart<WorksheetPart>();
                        var sheetData = new DocumentFormat.OpenXml.Spreadsheet.SheetData();
                        sheetPart.Worksheet = new DocumentFormat.OpenXml.Spreadsheet.Worksheet(sheetData);

                        DocumentFormat.OpenXml.Spreadsheet.Sheets sheets = workbook.WorkbookPart.Workbook.GetFirstChild<DocumentFormat.OpenXml.Spreadsheet.Sheets>();
                        string relationshipId = workbook.WorkbookPart.GetIdOfPart(sheetPart);

                        if (sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Count() > 0)
                        {
                            sheetId =
                                sheets.Elements<DocumentFormat.OpenXml.Spreadsheet.Sheet>().Select(s => s.SheetId.Value).Max() + 1;
                        }

                        DocumentFormat.OpenXml.Spreadsheet.Sheet sheet = new DocumentFormat.OpenXml.Spreadsheet.Sheet() { Id = relationshipId, SheetId = sheetId, Name = table.TableName };
                        sheets.Append(sheet);

                        DocumentFormat.OpenXml.Spreadsheet.Row headerRow = new DocumentFormat.OpenXml.Spreadsheet.Row();

                        List<String> columns = new List<string>();
                        foreach (DataColumn column in table.Columns)
                        {
                            columns.Add(column.ColumnName);

                            DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
                            cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
                            cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(column.ColumnName);
                            headerRow.AppendChild(cell);
                        }

                        sheetData.AppendChild(headerRow);

                        foreach (DataRow dsrow in table.Rows)
                        {
                            DocumentFormat.OpenXml.Spreadsheet.Row newRow = new DocumentFormat.OpenXml.Spreadsheet.Row();
                            foreach (String col in columns)
                            {
                                DocumentFormat.OpenXml.Spreadsheet.Cell cell = new DocumentFormat.OpenXml.Spreadsheet.Cell();
                                cell.DataType = DocumentFormat.OpenXml.Spreadsheet.CellValues.String;
                                cell.CellValue = new DocumentFormat.OpenXml.Spreadsheet.CellValue(dsrow[col].ToString()); //
                                newRow.AppendChild(cell);
                            }

                            sheetData.AppendChild(newRow);
                        }
                                      
                }

            }
            catch (Exception ex)
            {
                throw ex;
            }

        }

I have tried using a dataset and iterating for each datatable, this code breaks with Out of Memory exception , when the second datatable hits.

This method is called every time I am filling a datatable. I want to understand if this approach is correct, and how to save the file ? I would like to have only one excel file with multiple sheets. How to fix this?

Thanks