One-Phase Magic-sets Transformation (Extended Abstract)

) Inderpal Singh Mumick AT&T Bell Laboratories [email protected] Abstract Magic-sets transformation is typically applied to a program in two phases -- an adornment phase, and a magic-sets phase. A major drawback of the two-phase transformation is that join ordering, needed to do the adornment, must be done without knowledge of the actual predicates being pushed, and thereby without selectivity estimates and cardinality estimates. Consequently, two-phase implementations of the magic-sets transformation cannot do meaningful cost-based join optimization; and indeed they don't. A second drawback of the two-phase transformation is that when non-equijoin predicates, such as X ? Y , are being pushed using condition (c) adornments, complex adornments must be used to represent different types of non-equijoin predicates. In this paper we propose a one-phase transformation wherein the adornment and magicsets phases are interleaved. The interleaving enables us to see the predicates on a ru..