Here is the performance stats of the solution by pef for TSQL Challenge20.
| Attempt | Start Time | Reads | Writes | CPU | Duration (Sec) |
| 1 | Apr 21 2010 11:32PM | 835 | 0 | 16 | 0.0140 |
| 2 | Apr 22 2010 12:02AM | 835 | 0 | 15 | 0.0160 |
| 3 | Apr 22 2010 12:32AM | 835 | 0 | 0 | 0.0400 |
| 4 | Apr 22 2010 1:02AM | 835 | 0 | 16 | 0.0130 |
| 5 | Apr 22 2010 1:32AM | 835 | 0 | 15 | 0.0150 |