Physical Database Design

34 CHAPTER 3 Query Optimization and Plan Selection

3.2.5 Optimization Depth

Different database products have different search depth, the simplest being greedy

search, but there are usually more advanced dynamic programming-based approaches as

well. Often the search depth is a configurable parameter.

3.3

Query Cost Evaluation—An Example

The example in this section assumes that we have a basic query execution plan to work

with, and focuses on query cost evaluation to minimize I/O time to execute the query

whose plan we are given. It illustrates the benefit of applying well-known query optimi-

zation strategies to a simple real-life problem. Although the problem ...