You swear nothing changed - but suddenly your SQL Server has ground to a halt. Queries are slow across the board. You restart the server, rebuild indexes, or update statistics, and magically the problem goes away - but what really happened, and how do you fix it faster and more permanently?

Brent Ozar will explain what parameter sniffing is, show it happening live, explain why most people fix it the wrong way, and give you options to fix it long term.