An execution plan describes the operations carried out by the engine to execute a SQL statement. Every time you have to analyze a performance problem related to a SQL statement, or simply question the decisions taken by the query optimizer, you must know the execution plan. Without it, you’re like a blind man with his cane in the middle of the Sahara Desert, groping around trying to find his way. I can’t stress enough that the first thing to do while analyzing or questioning the performance of a SQL statement is to get its execution plan.
Whenever you deal with an execution plan, you carry out three basic actions: you ...