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Static optimization of logical queries is, in substance, to move selections down as far as possible inevaluating logical queries. This paper extends Ullman’s RGG (Rule/Goal Graph) and introduces P-graph, with which a wide range of recursive logical queries can be statically optimized top-down andevaluated bottom-up, some of which are usually optimized by dynamic approaches. The paper alsoshows that for some logical queries the complexity of pushing selections down and computing bottom-upis related to the complexity of base relation in the queries.
Static optimization of logical queries is, in substance, to move selections down as far as possible inevaluating logical queries. This paper extends Ullman’s RGG (Rule / Goal Graph) and introduces P-graph, with which a wide range of recursive logical queries can be statically optimized top-down andevaluated bottom-up, some of which are usually optimized by dynamic approaches. The paper alsoshows that for some logical queries the complexity of pushing selections down and computing bottom-upis related to the complexity of base relation in the queries.