Why does the SqlServer optimizer get so confused with parameters?

Question

I know this has something to do with parameter sniffing, but I\'m just perplexed at how something like the following example is even possible with a piece of technology that

Answer 1

It's probably caused by the fact that SQL Server compiles stored procedures and caches execution plans for them and the cached execution plan is probably unsuitable for this new set of parameters. You can try WITH RECOMPILE option to see if it's the cause.

EXECUTE MyProcedure [parameters] WITH RECOMPILE

WITH RECOMPILE option will force SQL Server to ignore the cached plan.