using better way to read the excel data

Question

Right now i am getting the data from excel and looping through the rows and based on condition i am processing the results like storing the result in an object for further processing.

The excel sheet is about 20 MB and the record count is closely to 7000 and i am using open xml to grab the data from excel file like as mentioned in below code.

        string filePath = @"C:\weather-Data\DesignConditions_p.xlsx";
        using FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
        using SpreadsheetDocument doc = SpreadsheetDocument.Open(fs, false);
        WorkbookPart workbookPart = doc.WorkbookPart;
        SharedStringTablePart sstpart = workbookPart.GetPartsOfType<SharedStringTablePart>().First();
        SharedStringTable sst = sstpart.SharedStringTable;

        Sheet firstSheet = workbookPart.Workbook.Descendants<Sheet>().First();
        Worksheet sheet = ((WorksheetPart)workbookPart.GetPartById(firstSheet.Id)).Worksheet;

        var rows = sheet.Descendants<Row>();
        var weatherDataList = new List<WeatherStation>();
        foreach (Row row in rows.Skip(5)) // it is taking almost more than 60 minutes to process and enter into the if loop below (country.Equals("USA"))
        {
            var weatherData = new WeatherStation();
            string country = GetCellValue(filePath, "Annual", $"B{row.RowIndex.ToString()}");
            if (country.Equals("USA"))
            {
                weatherData.CountryAbbreviation = country;
                weatherData.StateAbbreviation = GetCellValue(filePath, "Annual", $"C{row.RowIndex.ToString()}");
                weatherData.Number = GetCellValue(filePath, "Annual", $"E{row.RowIndex.ToString()}");
                ......
                .......
            }
        }

Could any one please point me in the right direction to optimize the processing time while reading the data from excel, I am using.Net Core for this application

Thanks in advance.

Answer 1

You could use the 'SAX' approach, that way you're reading the file in parts so processing and IO could be faster.:

// The SAX approach.
    static void ReadExcelFileSAX(string fileName)
    {
        using (SpreadsheetDocument spreadsheetDocument = SpreadsheetDocument.Open(fileName, false))
        {
            WorkbookPart workbookPart = spreadsheetDocument.WorkbookPart;
            WorksheetPart worksheetPart = workbookPart.WorksheetParts.First();

            OpenXmlReader reader = OpenXmlReader.Create(worksheetPart);
            string text;
            while (reader.Read())
            {
                if (reader.ElementType == typeof(CellValue))
                {
                    text = reader.GetText();
                    Console.Write(text + " ");
                }
            }
            Console.WriteLine();
            Console.ReadKey();
        }
    }

https://docs.microsoft.com/en-us/office/open-xml/how-to-parse-and-read-a-large-spreadsheet

Other than that you could look for a library/nuget package that has some faster reading, because i see no impact-full ways to tune this code more.