Three men are in a hot-air balloon. Soon, they find themselves lost in a canyon somewhere. One of the three men says, “I’ve got an idea. We can call for help in this canyon and the echo will carry our voices far.” So he leans over the basket and yells out, “Helllloooooo! Where are we?” (They hear the echo several times.)
Fifteen minutes pass. Then they hear this echoing voice: “Helllloooooo! You’re lost!!” One of the men says, “That must have been a statistician.” Puzzled, one of the other men asks, “Why do you say that?”
The reply: “For three reasons: 1) he took a long time to answer, 2) he was absolutely correct, and 3) his answer was absolutely useless.”
Well, thats pretty much what happens to your queries when statistics go wrong on SQL Server.
SQL Server takes ages to come back and whilst your results remain correct, the effects could make your entire SQL Server useless for the rest of the queries.
So here’s an article to help identify statistics that’s potentially the cause of the problems.