In-Memory OLTP (codename Hekaton) was introduced in SQL Server 2014. The promise of ultra-high performance data processing inside SQL Server was a major feature when SQL Server 2014 was released. As expected with version-1 features, there were a wide range of limitations in the initial release and this prevented many customers from being able to adopt the technology. With SQL Server 2017, a great number of these limitations have been either raised to a higher threshold or completely removed. In-Memory OLTP has received the required maturity and extension in feature set to make it viable for prime production deployment. Chapter 11, Introducing SQL Server In-Memory OLTP will show an introduction to In-Memory OLTP, explaining how the technology works under the hood and how the initial release of the feature works in SQL Server 2014. Chapter 12, In-Memory OLTP Improvements in SQL Server 2017 will build on top of the introduction and explain how the feature has matured and improved with the release of SQL Server 2016 and 2017.