Evaluation of database recursive logic programs as recurrent function series

Abstract

The authors introduce a new method to compile queries referencing recursively defined predicates. This method is based on an interpretation of the query and the relations as functions which map one column of a relation to another column. It is shown that a large class of queries with associated recursive rules, including mutually recursive rules, can be computed as the limit of a series of functions. Typical cases of series of functions are given and solved. The solutions lend themselves towards either extended relational algebra or SQL optimized programs to compute the recursive query answers. Examples of applications are given.