The Relational engine equipment the relational data store using the capability provided by SQLOS, which is exposed to this layer via the private SQLOS API. It equipment the type system, to define the types of the data that can be store in the tables, as well as the diverse types of data items that can be stored. It includes the Storage Engine, which handles the way data is stored on constant storage devices and provides methods for fast admission to the data. The storage engine implements log-based business to ensure that any changes to the data are ACID obedient. It also includes the query processor, which is the component that retrieves data. SQL queries specify what data to retrieve, and the query processor optimizes and translates the query into the succession of operations needed to get back the data. The operations are then performing by worker threads, which are scheduled for carrying out by SQLOS.