Improving Microsoft DataGrid CTP sorting performance - Part 2
In this blog I wrote how you can improve Microsoft DataGrid CTP by providing your own custom sort.
As one of the comments suggested you can get even better performance by using delegates.
I have changed MySort code below and I now use delegates to avoid the switch comparison that was called on every compare during the QuickSort . I can now see additional ~50% speed gain during sort.
In my 300,000 rows DataGrid, before I saw sort speed decreased from almost 5 minutes to 2.4 seconds and now the String type columns (e.g. Name, Position) are sorted in 1.4 sec while the Integer type columns (e.g. Id) are now sorted in 400 ms!
1: public class MySort : IComparer
2: { 3: public delegate int TwoArgDelegate(Employee arg1, Employee arg2);
4: TwoArgDelegate myCompare;
5: public MySort(ListSortDirection direction, DataGridColumn column)
6: { 7: int dir = (direction == ListSortDirection.Ascending) ? 1 : -1;
8: //set a delegate to be called by IComparer.Compare
9: switch ((string)column.Header)
10: { 11: case "Id":
12: myCompare = (a, b) => { return a.Id.CompareTo(b.Id) * dir; }; 13: break;
14: case "Name":
15: myCompare = (a, b) => { return a.Name.CompareTo(b.Name) * dir; }; 16: break;
17: case "Position":
18: myCompare = (a, b) => { return a.Position.CompareTo(b.Position) * dir; }; 19: break;
20: case "Tel":
21: myCompare = (a, b) => { return a.Telephone.CompareTo(b.Telephone) * dir; }; 22: break;
23: case "Email":
24: myCompare = (a, b) => { return a.Email.CompareTo(b.Email) * dir; }; 25: break;
26: case "Enabled":
27: myCompare = (a, b) => { return a.Enabled.CompareTo(b.Enabled) * dir; }; 28: break;
29: case "City":
30: myCompare = (a, b) => { return a.City.CompareTo(b.City) * dir; }; 31: break;
32: case "Country":
33: myCompare = (a, b) => { return a.Country.CompareTo(b.Country) * dir; }; 34: break;
35: default:
36: myCompare = (a, b) => { return 0; }; 37: break;
38: }
39: }
40: int IComparer.Compare(object X, object Y)
41: { 42: return myCompare((Employee)X, (Employee)Y);
43: }
44: }
45: }
