IBM System R

IBM System R is a database system built as a research project at IBM's San Jose Research Laboratory beginning in 1974,^[1] led by Edgar Codd, to implement his ideas on relational databases.^[2] System R was a seminal project as the first implementation of SQL, which has since become the standard relational data query language. It was also the first system to demonstrate that a relational database could provide good transaction processing performance. Design decisions in System R, as well as some fundamental algorithm choices (such as the dynamic programming algorithm used in query optimization^[3]), influenced many later relational systems.

System R's first customer was Pratt & Whitney in 1977.^[4] Not running on Unix hurt its popularity.^[2]

^ "A History and Evaluation of System R" (PDF). IBM. "Phase Zero" of the project, which occurred during 1974 and-most of 1975, involved the development of the SQL user interface
^ ^a ^b "RDBMS Plenary 1: Early Years" (PDF) (Interview). Interviewed by Burton Grad. Computer History Museum. 2007-06-12. Retrieved 2025-05-30.
^ Selinger, PG; Astrahan, MM; Chamberlin, Donald D; Lorie, RA; Price, TG (1979), "Access Path Selection in a Relational Database Management System", Proceedings of the 1979 ACM SIGMOD International Conference on Management of Data, pp. 23–34, doi:10.1145/582095.582099, ISBN 978-0897910019, S2CID 8537523
^ McJones, P (1995), "SQL reunion", System R.