Control of an Extensible Query Optimizer: A Planning-Based Approach
Gail Mitchell, Umeshwar Dayal, Stanley B. Zdonik · 1993
In this paper we address the problem of controlling the execution of a query optimizer. We describe a control for the optimization process that is based on planning. The controller described here is a goal-directed planner that intermingles planning with the execution of query transformations, and uses execution results to direct further planning of optimizer processing. We describe this control in the context of the Epoq extensible architecture. Epoq is an approach to extensible query optimization that integrates specialized rewrite strategies through its extensible control mechanism. This paper describes our planning-based approach to extensible control and illustrates it with a simple example. 1 Introduction Optimization of a query is inherently a process of searching the space of expressions equivalent to the query. Typically, a given optimizer can only visit some portion of this space, since the set of transformation rules is usually incomplete, the cost of optimization must be ...