Recursive Strategies for Answering Recursive Queries - The RQA/FQI Strategy
Wolfgang Nejdl · Very Large Data Bases · 1987
In this paper we will discuss several methods for recursive query processing using a recursive control structure. We will describe the QSQR method, introduced in [Vie861 and show that it fails to produce all answers in certain cases. After analyzing the causes of this failure we propose an improved algorithm the RQA/FQI Strategy which is complete over the domain of function-free Horn clauses. The new method uses a two step approach recursive expansion + an efficient variant of LFP iteration to evaluate recursive queries. A short comparison of these methods shows the efficiency of RQA/FQI.