A Blackboard Architecture for Query Optimization in Object Bases
Alfons Kemper, Guido Moerkotte, Klaus Peithner · MADOC (University of Mannheim) · 1993
Adopting the blackboard architecture from the area of Artificial Intelligence, a novel kind of optimizer enabling two desirable ideas will be proposed. Firstly, using such a well-structured approach backpropagation of the optimized queries allows an evolutionary improvement of (crucial) parts of the optimizer. Secondly, the A 3 search strategy can be applied to harmonize two contrary properties: Alternatives are generated whenever necessary, and straight-forward optimizing is performed whenever possible, however. The generic framework for realizing a blackboard optimizer is proposed first. Then, in order to demonstrate the viability of the new approach, a simple example optimizer is presented. It can be viewed as an incarnation of the generic framework. 1 Introduction Query optimizers---no matter whether relational or object-oriented---are among the most complex software systems that have been built. Therefore, it is not surprising that the design of query optimizers is still a "hot...