Influencing plan generation in the context of the two phase query optimization approach

摘要

Techniques are described herein for influencing plan generation in context of the two phase query optimization approach. Types of pruning criteria including method pruning criteria, total cost pruning criteria, and permutation pruning criteria exist in cost-based plan generators to determine what parts of a query statement should be offloaded to a query offload engine. Method pruning criteria is responsible to determine an optimal joining method. Total cost pruning criteria compares accumulated costs with a lowest plan cost determined so far. Permutation pruning criteria is responsible for selecting the cheapest query execution plan from all considered query execution plans. Each type of pruning criteria is modified to favor offload engine execution upon request.