Linq, how to put a indexes on Linq Query

Question

I want to render a dates from list to the ASP Calendar.

My list look like this:

Kontrakt | Pracownik | Dzien | ID | Procenty
--------------------------------------------

I made Linq Query, but it's doing quite long, about 3-4 secunds. How to put indexes on it?

     `   SPWeb witryna = SPContext.Current.Web;
        SPListItemCollection listaDniNaProjektDropDownList = witryna.Lists["Szczegoly"].Items;
        //Link technology
            QumakDataContext qumak = new QumakDataContext("http://gzawistowskilap");
            var szczegoly = from szczegolyQumak in qumak.Szczegoly
                            orderby szczegolyQumak.Dzien 

                            select new {szczegolyQumak.Dzien, szczegolyQumak.Kontrakt};

            foreach(var zmiennaSzczegoly in szczegoly ){

                Label1.Text +=zmiennaSzczegoly.Dzien + zmiennaSzczegoly.Kontrakt + "<br />";
            }`

Answer 1

Indexes are not created in SPQuery, but you can create indexes on columns involved in joins, where clauses from Indexed Column option:

You can read about Indexing and Query Throttling here

Also, as Salvatore Di Fazio said... replace the above code as below:

SPWeb witryna = SPContext.Current.Web;
SPListItemCollection listaDniNaProjektDropDownList = witryna.Lists["Szczegoly"].Items;
//Link technology
QumakDataContext qumak = new QumakDataContext("http://gzawistowskilap");
var szczegoly = from szczegolyQumak in qumak.Szczegoly
                orderby szczegolyQumak.Dzien 

               select new {szczegolyQumak.Dzien, szczegolyQumak.Kontrakt};
StringBuilder str = new StringBuilder(string.Empty);

foreach(var zmiennaSzczegoly in szczegoly ){
    str.Append(zmiennaSzczegoly.Dzien + zmiennaSzczegoly.Kontrakt + "<br />");
}

Label1.Text = str.ToString();

You will need to add reference as using System.Text;