Last year when I presented my session regarding the Query Optimizer at the PASS Summit and at a couple of local user groups, I was asked how the estimated CPU and I/O costs in an execution plan are calculated. Since Microsoft does not publish how these costs are calculated all I could say was that each operator cost depends on the operator ...

Did you know that the Database Engine Tuning Advisor (DTA) uses the Query Optimizer to help you to create indexes, indexed views, and partitions for your databases? The DTA uses the Query Optimizer to estimate the cost of queries so it can select the choices with the lowest estimated cost. But, how can the Query Optimizer estimate the cost of a ...