RAL : relational algebra language

Abstract

This thesis describes a Data Base Management System (DBMS) that has been designated and developed at the University of St. Andrews, using a PDP 11/40 computer and the UNIX (1) operating system. The system is a general purpose Data Base Management System supporting a relational view of data and has been developed for applications of small and medium complexity and size. At the level of the user interface, the system offers a sublanguage based on the relational algebra, and the chosen operators are similar to the ones suggested by Codd (2). This language decision is in opposition to a sublanguage based on a first predicate calculus which other relational DBMS of similar capabilities offer. The thesis discusses the concepts on which the system is based, the power of expression of the language offered to the user of it and implementation techniques and related problems. Furthermore, an evaluation of the implementation of RAL suggests ways of improving the performance of the system enhancing its power and flexibility.