There are any number of tricks and traps around getting the query optimizer to provide you with an optimal execution plan that gets you your data quickly and efficiently. But, at the end of the day, the principal driving factor of the optimizer, and therefore of your queries, are the statistics that define your data. This session teaches you how those statistics are put together and maintained by SQL Server. Different types of maintenance results in different levels of accuracy within statistics so we detail what the structures and information looks like after this maintenance. Your understanding of how the optimizer works with statistics will better enable you to understand why you’re getting the performance and types of execution plans that you are getting. Understanding enables you to write better t-sql statements and deal with performance problems such as bad parameter sniffing.