Question

My WPF application has a lookup screen for selecting customers. The customer table contain nearly 10,000 records. Its very slow when loading and filtering records using my Linq query(I am not doing any ordering of records). Is there a way to increase speed? Heard about using indexed views. Can someone please give some ideas?

lstCustomerData = dbContext.customers.Where(c => c.Status == "Activated").ToList();
            dgCustomers.ItemsSource = lstCustomerData;

filtering:

 string searchKey = TxtCustName.Text.Trim();

            var list = (from c in lstCustomerData
                        where (c.LastName == null ? "" : c.LastName.ToUpper()).Contains(searchKey.ToUpper())
                        select c).ToList();
            if (list != null)
                dgCustomers.ItemsSource = list;

Answer 1

Depends on what is slow. is the SQL Query slow? Is the UI rendering slow? Are you sorting/fintering in memory or going back to the DB?

You should profile your app to find out exactly what the slowest piece is, then tackle that first.

If the Linq query you added is what is slow then adding an index to the Status column in your database may help.

You might get some improvement by changing your Where clause:

var list = (from c in lstCustomerData
            where (c.LastName != null && c.LastName.ToUpper()).Contains(searchKey.ToUpper())
            select c).ToList();
if (list != null)
    dgCustomers.ItemsSource = list; 

since it doesn’t have to compare an empty string. However if you have very few NULL records than this probably won’t help much.

In this case, however, all of the filtering is done in memory so using an indexed view in the DB won’t help unless you push the filtering back to the source repository.