Response.WriteFile writing the content twice

Question

Here is my code..

 string attachment = "attachment; filename=Call-Details-Report-" + startDate.SelectedDate.Value.ToString("MM-dd-yyyy") + ".csv";
        Response.Clear();
        Response.ClearHeaders();
        Response.ClearContent();
        Response.AddHeader("Content-Disposition", attachment);
        Response.ContentType = "text/csv";
        Response.AddHeader("Pragma", "public");
        Response.WriteFile(downloadLocation+"\\"+fileName);
        Response.End();

I'm using the above code to download a csv file from a location.But surprisingly the contents gets written twice or some times thrice into the file that i download though actually it isn't so with the file on server.I'm writing my code in c#. The above piece of code works perfectly in local machine,but the issue is in Production server.

Here is my complete Method

 private void DownloadReport(string query)
{
    string downloadFolderPath = "";
    string filePath = "";
    string dbAndApplicationServerStatus = ConfigurationManager.AppSettings["SameDBAndApplicationServer"] != null ? ConfigurationManager.AppSettings["SameDBAndApplicationServer"] : "1";
    if (dbAndApplicationServerStatus == "0")
    {
        Log.Write("So the DB And Application are on differrent servers,hence trying to read Download folder path on DB Server....");
        downloadFolderPath = ConfigurationManager.AppSettings["ReportDownloadLocation"] != null ? ConfigurationManager.AppSettings["ReportDownloadLocation"] : "-1";
        Log.Write("Download Path is " + downloadFolderPath);
    }
    else
    {
        Log.Write("So the DB and Application and Db are on same server......");
        downloadFolderPath = Server.MapPath("Download");
        downloadFolderPath = downloadFolderPath.Replace("\\", "//");
        if (!Directory.Exists(downloadFolderPath))
        {
            Directory.CreateDirectory(downloadFolderPath);
        }
        Log.Write("Download Path is " + downloadFolderPath);
    }
    string status="";
    StringBuilder headerQuery = new StringBuilder();
    StringBuilder rowQuery = new StringBuilder();
    StringBuilder sqlQuery = new StringBuilder();
    filePath = downloadFolderPath;
    string folderName = DateTime.Now.ToString("MM-dd-yyyy");

    string timeStamp = DateTime.Now.ToString("MM-dd-yy-HH-mm-ss");
    string fileName = "Call-Details-Report-" + startDate.SelectedDate.Value.ToString("MM-dd-yyyy") + "_" + timeStamp + ".csv";
    filePath = filePath + "/" + fileName;

    bool commaRequired = false;

    sqlQuery.Append("SELECT * INTO OUTFILE '");
    sqlQuery.Append(filePath);
    sqlQuery.Append("' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' LINES TERMINATED BY '\n' FROM (");
    headerQuery.Append("Select ");
    rowQuery.Append("(Select ");

    #region Creating Query
    /*Sql Query is Created  in this region*/
    #endregion



    if (!CdrSearch.WriteReportToFile(sqlQuery.ToString(),out status))
    {
        Log.Write("Failed to generate the file to download......");
        WebPagesHelper.ShowMessage(ref lblMessage, WebPagesHelper.MessageType.Message, status);
    }
    else
    {
        Log.Write("Succesfully generated file to Download");
        string downloadLocation = Server.MapPath("Download");
        if (dbAndApplicationServerStatus == "0")
        {
            WebClient webClient = new WebClient();
            string path = ConfigurationManager.AppSettings["DownloadURL"] != null ? ConfigurationManager.AppSettings["DownloadURL"].ToString() : "";

            if (!Directory.Exists(downloadLocation))
            {
                Directory.CreateDirectory(downloadLocation);
            }
            if (File.Exists(downloadLocation + "\\" + fileName))
            {
                File.Delete(downloadLocation + "\\" + fileName);
            }
            webClient.DownloadFile(path + fileName, downloadLocation + "\\" + fileName);

        }
        Log.Write("Configured Download Location on Application" + downloadLocation);
        string attachment = "attachment; filename=Call-Details-Report-" + startDate.SelectedDate.Value.ToString("MM-dd-yyyy") + ".csv";
        Response.Clear();
        Response.ClearHeaders();
        Response.ClearContent();
        Response.AddHeader("Content-Disposition", attachment);
        Response.ContentType = "text/csv";
        Response.AddHeader("Pragma", "public");

        Log.Write(downloadLocation + "\\" + fileName);

        Response.WriteFile(downloadLocation+"\\"+fileName);
        Response.SetCookie(new HttpCookie("DStatus", "Completed"));
        Response.End();
    }
}

And the above method is called only once straight away on click of a button,so no question of any looping here.

Answer 1

ok so the real culprit was Response.WriteFile in this case.In my case i guess since the size of data was quite huge Response.WriteFile was not working as expected.I found some where that in case of large file downloads, its best to use Response.TransmitFile.Left with no other option i changed my code and used Response.TransmitFile and eureka! the problem was solved.No more duplicate records in downloaded file.Though the reason is still unknown, Response.TransmitFile solved the issue.....