In this chapter, you learned about the architecture of SQL Server Relational Engine. You also learned about SQL Server 2014 in-memory technology. You learned about SQL Server indexes and how they help achieve optimal query performance while reducing the overall response time. You got an understanding of the architectural differences between the B-tree, Bw-tree, and xVelocity columnstore indexes. You also got an idea of the purpose of SQL Server query optimization statistics. You learned about SQL Server transactions and locks. You also learned about the tools that come with SQL Server Database Engine, which you can use to monitor and troubleshoot the performance of SQL Server.