SQL Tuning (Paperback)

Summary

A poorly performing database application not only costs users time, but also has an impact on other applications running on the same computer or the same network. SQL Tuning provides an essential next step for SQL developers and database administrators who want to extend their SQL tuning expertise and get the most from their database applications.

There are two basic issues to focus on when tuning SQL: how to find and interpret the execution plan of an SQL statement and how to change SQL to get a specific alternate execution plan. SQL Tuning provides answers to these questions and addresses a third issue that's even more important: how to find the optimal execution plan for the query to use.

Author Dan Tow outlines a timesaving method he's developed for finding the optimum execution plan--rapidly and systematically--regardless of the complexity of the SQL or the database platform being used. You'll learn how to understand and control SQL execution plans and how to diagram SQL queries to deduce the best execution plan for a query. Key chapters in the book include exercises to reinforce the concepts you've learned. SQL Tuning concludes by addressing special concerns and unique solutions to "unsolvable problems."

Whether you are a programmer who develops SQL-based applications or a database administrator or other who troubleshoots poorly tuned applications, SQL Tuning will arm you with a reliable and deterministic method for tuning your SQL queries to gain optimal performance.

Table of Contents

Foreword

Preface

1. Introduction

     Why Tune SQL?

     Who Should Tune SQL?

     How This Book Can Help

     A Bonus

     Outside-the-Box Solutions

2. Data-Access Basics

     Caching in the Database

     Tables

     Indexes

     Uncommon Database Objects

     Single-Table Access Paths

     Calculating Selectivity

     Joins

3. Viewing and Interpreting Execution Plans

     Reading Oracle Execution Plans

     Reading DB2 Execution Plans

     Reading SQL Server Execution Plans

4. Controlling Execution Plans

     Universal Techniques for Controlling Plans

     Controlling Plans on Oracle

     Controlling Plans on DB2

     Controlling Plans on SQL Server

5. Diagramming Simple SQL Queries

     Why a New Method?

     Full Query Diagrams

     Interpreting Query Diagrams

     Simplified Query Diagrams

     Exercises

6. Deducing the Best Execution Plan

     Robust Execution Plans

     Standard Heuristic Join Order

     Simple Examples

     A Special Case

     A Complex Example

     Special Rules for Special Cases

     Exercise

7. Diagramming and Tuning Complex SQL Queries

     Abnormal Join Diagrams

     Queries with Subqueries

     Queries with Views

     Queries with Set Operations

     Exercise

8. Why the Diagramming Method Works

     The Case for Nested Loops

     Choosing the Driving Table

     Choosing the Next Table to Join

     Summary

9. Special Cases

     Outer Joins

     Merged Join and Filter Indexes

     Missing Indexes

     Unfiltered Joins

     Unsolvable Problems

10. Outside-the-Box Solutions to Seemingly Unsolvable Problems

     When Very Fast Is Not Fast Enough

     Queries that Return Data from Too Many Rows

     Tuned Queries that Return Few Rows, Slowly

A. Exercise Solutions

B. The Full Process, End to End

Glossary

Index