Processing a large text file in C #

Question

I have 4GB + text files (csv format) and I want to process this file using linq in C #.

Am I running a complex linq query after loading csv and converting to a class?

but the file size is 4gb, although the application’s memory is twice the size of the file.

How can I process (linq and new result) large files?

thank

Answer 1

Instead of loading the entire file into memory, you can read and process the file line by line.

using (var streamReader = new StreamReader(fileName))
{
    string line;
    while ((line = streamReader.ReadLine()) != null)
    {
        // analize line here
        // throw it away if it does not match
    }
}

[EDIT]

, - .

Answer 2

, ... CSV

Answer 3

.NET 4.0, Clay, , IEnumerable , ,

from record in GetRecords("myFile.csv",new []{"Foo","Bar"},new[]{","})
where record.Foo == "Baz"
select new {MyRealBar = int.Parse(record.Bar)

CSV Clay :

 private IEnumerable<dynamic> GetRecords(
                    string filePath,
                    IEnumerable<string> columnNames, 
                    string[] delimiter){
            if (!File.Exists(filePath))
                yield break;
            var columns = columnNames.ToArray();
            dynamic New = new ClayFactory();
            using (var streamReader = new StreamReader(filePath)){
                var columnLength = columns.Length;
                string line;
                while ((line = streamReader.ReadLine()) != null){
                    var record = New.Record();
                    var fields = line.Split(delimiter, StringSplitOptions.None);
                    if(fields.Length != columnLength)
                        throw new InvalidOperationException(
                                 "fields count does not match column count");
                    for(int i = 0;i<columnLength;i++){
                        record[columns[i]] = fields[i];
                    }
                    yield return record;
                }
            }
        }