| 摘要 |
The present invention demonstrates the development and application of the chase/backchase ("C&B") technique to systematically optimize generating alternative query plans, aimed at multiple disparate targets. It further provides a first optimization prototype that uses path-conjunctive query graphs internally. The methods, systems, apparatus and techniques of the present invention capture and extend many aspects of semantic optimizations, physical data independence, use of materialized views and cached queries, as well as generalized tableau-like minimization. Moreover, using a uniform representation with constraints, the techniques make these disparate optimization principles highly cooperative.This present invention provides a new class of optimization opportunities, such as the non-trivial use of indexes and materialized views enabled only by the presence of certain integrity constraints. Moreover, the technique is valuable when only the presence of semantic integrity constraints enables the use of physical access structures or materialized views.
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