In 1970 E. F. Codd of the IBM Research Laboratory produced his highly influential paper on the relational data model. This paper was very timely and addressed the disadvantages of the former approaches. Many experimental relational DBMSs were implemented thereafter, with the first commercial products appearing in the late 1970s and early 1980s. Of particular note is the System R project at IBM’s San José Research Laboratory in California, which was developed during the late 1970s (Astrahan et al., 1976). This project was designed to prove the practicality of the relational model by providing an implementation of its data structures and operations, and led to two major developments: