15Nov 2010 by Grant Fritchey 4 Comments

Switching Off Parameter Sniffing

Uncategorized
Or, another way to put it, in most cases, shooting yourself in the foot. I was not aware that the cumulative update for SQL Server 2008 back in June included a switch that allows you to turn parameter sniffing off within SQL Server. Thanks to Kendra Little (blog|twitter) for letting me know about it (although she let me know by "stumping the chump" during my lightening talk at the Summit, thanks Kendra!). When I first saw the switch, I thought about the places where switching off parameter sniffing could be helpful. But, as I thought about it, the more I realized that this was an extremely dangerous switch. Why? Because, most people only ever hear about parameter sniffing when they run into a problem. Someone says "Parameter sniffing" and you see people cringe.…
Read More
27Sep 2010 by Grant Fritchey 3 Comments

Parameter Name Size And Performance

SQL Server, T-SQL
I saw an odd statement the other day, "The size of the name of the parameter does not affect performance." My first thought was, "Well, duh!" But then, I had one of those, "Ah, but are you sure" thoughts. And you know what, I wasn't sure. If size of the parameter name did affect performance, I figured, the one sure place where that would be evident is in the size of the execution plan. Right? I mean, if there was an impact on memory, and hence on performance, that's probably where you'd see evidence of it. I wrote two queries: DECLARE @ThisIsAVeryVeryLongParameterNameThatIsTrulyRidiculousButItIllustratesThePointThatParameterLengthDoesNotAffectPerformance int SET @ThisIsAVeryVeryLongParameterNameThatIsTrulyRidiculousButItIllustratesThePointThatParameterLengthDoesNotAffectPerformance = 572 SELECT soh.SalesOrderID ,sod.SalesOrderDetailID FROM Sales.SalesOrderHeader AS soh JOIN Sales.SalesOrderDetail AS sod ON soh.SalesOrderID = sod.SalesOrderID WHERE soh.SalesOrderID = @ThisIsAVeryVeryLongParameterNameThatIsTrulyRidiculousButItIllustratesThePointThatParameterLengthDoesNotAffectPerformance DECLARE @v int SET…
Read More