Un moyen efficace de lire un gros fichier TXT délimité?

Question

J'ai un fichier TXT délimité par onglet avec 500K enregistrements.J'utilise le code ci-dessous pour lire les données sur DataSet.Avec 50k, cela fonctionne bien mais 500k il donne «l'exception du type» System.outofMemoryException 'a été lancé. "

Quel est le moyen le plus efficace de lire de grandes données délimitées? Ou comment résoudre ce problème?S'il vous plaît donnez-moi un exemple

public DataSet DataToDataSet(string fullpath, string file)
{
    string sql = "SELECT * FROM " + file; // Read all the data
    OleDbConnection connection = new OleDbConnection // Connection
                  ("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fullpath + ";"
                   + "Extended Properties=\"text;HDR=YES;FMT=Delimited\"");
    OleDbDataAdapter ole = new OleDbDataAdapter(sql, connection); // Load the data into the adapter
    DataSet dataset = new DataSet(); // To hold the data
    ole.Fill(dataset); // Fill the dataset with the data from the adapter
    connection.Close(); // Close the connection
    connection.Dispose(); // Dispose of the connection
    ole.Dispose(); // Get rid of the adapter
    return dataset;
}

Answer 1

Use a stream approach with TextFieldParser - this way you will not load the whole file into memory in one go.

Answer 2

You really want to enumerate the source file and process each line at a time. I use the following

    public static IEnumerable<string> EnumerateLines(this FileInfo file)
    {
        using (var stream = File.Open(file.FullName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
        using (var reader = new StreamReader(stream))
        {
            string line;
            while ((line = reader.ReadLine()) != null)
            {
                yield return line;
            }
        }
    }

Then for each line you can split it using tabs and process each line at a time. This keeps memory down really low for the parsing, you only use memory if the application needs it.

Answer 3

Have you tried the TextReader?

  using (TextReader tr = File.OpenText(YourFile))
  {
      string strLine = string.Empty;
      string[] arrColumns = null;
      while ((strLine = tr.ReadLine()) != null)
      {
           arrColumns = strLine .Split('\t');
           // Start Fill Your DataSet or Whatever you wanna do with your data
      }
      tr.Close();
  }

Answer 4

I found FileHelpers

The FileHelpers are a free and easy to use .NET library to import/export data from fixed length or delimited records in files, strings or streams.

Maybe it can help.