Classification and Compilation of Linear Recursive Queries in Deductive Databases

In this paper, we present a graph model which is powerful in classifying and compiling linear recursive formulas in deductive databases. The graph model consists of two kinds of graphs: I-graph and Resolution Graph. We can extract essential properties of a recursive formula from its I-graph and can easily figure out the compiled formula and the query evaluation plan of the recursive formula from its resolution graph. We demonstrate that based on the graph model all the linear recursive formulas can be classified into a taxonomy of classes and each class shares some common characteristics in query compilation and query processing. The compiled formulas and the corresponding query evaluation plans can be derived based on the study of the compilation of each class.