This chapter covered some performance pitfalls that are not always obvious when writing T-SQL queries. Using the knowledge and tools covered in earlier chapters, together with the anti-patterns discussed in this chapter, we should now be able to dig deeper into our query execution plans and uncover issues that have the potential to impact performance and scalability before they reach production. So far, we have been focusing on how to write efficient, performant T-SQL code, but what if the code is already written, and we are faced with identifying these issues in an existing system?
In the next and final part of the book, we will investigate some of the tools available in SQL Server that will help us to identify and troubleshoot issues with our T-SQL query performance.