SAS® Certification Prep Guide: Advanced Programming for SAS®9, Third Edition

Chapter 24Querying Data Efficiently

Overview

Introduction

Objectives

Prerequisites

Using an Index for Efficient WHERE Processing

Overview

Accessing Data Sequentially

Example

Accessing Data Directly

Example

Benefits and Costs of Using an Index

How SAS Selects an Access Method

Identifying Available Indexes

Overview

Example: Identifying One Available Index

Example: Identifying Multiple Available Indexes

Compound Optimization

Example: Composite Index That Can Be Used to Optimize Multiple Conditions

Example: Composite Index That Can Be Used to Optimize One Condition

Example: Composite Index That Cannot Be Used for Optimizing

Identifying Conditions That Can Be Optimized

Requirements for Optimizing a Single WHERE Condition

WHERE Conditions That Cannot ...