Physical Data Independence, Constraints, and Optimization with Universal Plans

We present an optimization method and algorithm designed for three objectives: physical data independence, semantic optimization, and generalized tableau minimization. The method relies on generalized forms of chase and \backchase" with constraints (dependencies). By using dictionaries ( nite functions) in physical schemas we can capture with constraints useful access structures such as indexes, materialized views, source capabilities, access support relations, gmaps, etc. The search space for query plans is de ned and enumerated in a novel manner: the chase phase rewrites the original query into a \universal" plan that integrates all the access structures and alternative pathways that are allowed by applicable constraints. Then, the backchase phase produces optimal plans by eliminating various combinations of redundancies, again according to constraints. This method is applicable (sound) to a large class of queries, physical access structures, and semantic constraints. We p...

• Type: Conference
• Year: 1999
• Where: VLDB
• Authors: Alin Deutsch, Lucian Popa, Val Tannen
• Keywords: Access Structures, Constraints Useful Access, Database, Materialized Views, VLDB 1999