Join Ordering for Constraint Handling Rules: Putting Theory into Practice
نویسنده
چکیده
Join ordering is the NP-complete problem of finding the optimal order in which the different conjuncts of multi-headed rules are joined. Join orders are the single most important determinants for the runtime complexity of CHR programs. Nevertheless, all current systems use ad-hoc join ordering heuristics, often using greedy, very error-prone algorithms. As a first step, Leslie De Koninck and Jon Sneyers therefore worked out a more realistic, flexible formal cost model. In this work-in-progress paper, we show how we created a first practical implementation of static join ordering based on their theoretical model.
منابع مشابه
Join Ordering for Constraint Handling Rules
Join ordering is the problem of finding cost optimal execution plans for matching multi-headed rules. In the context of Constraint Handling Rules, this topic has received limited attention so far, even though it is of great importance for efficient CHR execution. We present a formal cost model for joins and investigate the possibility of join optimization at runtime. We propose some heuristic a...
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