Microsoft® SQL Server 2012 Unleashed

Common Query Optimization Problems

So you’ve written a query and examined the query plan, and performance isn’t what you expected. It might appear that SQL Server isn’t choosing the appropriate query plan that you expect. Is something wrong with the query or with the Query Optimizer? Before delving into a detailed discussion about how to debug and analyze query plans (covered in detail in Chapter 32), the following sections look at some of the most common problems and SQL coding issues that can lead to poor query plan selection.