SQL Tuning: Generating Optimal Execution Plans

by Dan Tow

Overview

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.

Product Details

ISBN-13:	9780596552367
Publisher:	O'Reilly Media, Incorporated
Publication date:	11/19/2003
Sold by:	Barnes & Noble
Format:	eBook
Pages:	338
File size:	6 MB

About the Author

Dan Tow is an independent consultant, operating under the banner SingingSQL (www.singingsql.com). His experience solving Oracle-related performance problems goes all the way back to his 1989 hire by Oracle Corporation. During most of his tenure at Oracle, Dan focused on the performance of Oracle Applications, managing the performance group for that division. In this role, he found a fertile testing ground for his SQL tuning method applied to the huge set of complex SQL included in those applications, including both online SQL and diverse batch processes. In 1998, Dan left Oracle to lead performance for TenFold Corporation, where he applied the same methods to tuning questions on DB2, and SQL Server, and Sybase, as well as on Oracle. In 2002, Dan started his own business, SingingSQL, through which he offers diverse database-related tuning services, including SQL tuning and systematically analyzing load to learn which SQL should be tuned. He has introduced his SQL tuning method to over 1,000 people in short lectures, and now offers in-depth courses in the material, using this book as textbook. Dan has a Ph.D. in chemical engineering from the University of Wisconsin at Madison. He lives in Palo Alto, California, and can be reached at [e-mail].

Table of Contents

	Foreword	xi
	Preface	xiii
1.	Introduction	1
	Why Tune SQL?	1
	Who Should Tune SQL?	3
	How This Book Can Help	4
	A Bonus	6
	Outside-the-Box Solutions	7
2.	Data-Access Basics	8
	Caching in the Database	9
	Tables	12
	Indexes	15
	Uncommon Database Objects	18
	Single-Table Access Paths	22
	Calculating Selectivity	27
	Joins	36
3.	Viewing and Interpreting Execution Plans	43
	Reading Oracle Execution Plans	44
	Reading DB2 Execution Plans	54
	Reading SQL Server Execution Plans	65
4.	Controlling Execution Plans	73
	Universal Techniques for Controlling Plans	73
	Controlling Plans on Oracle	84
	Controlling Plans on DB2	98
	Controlling Plans on SQL Server	102
5.	Diagramming Simple SQL Queries	108
	Why a New Method?	108
	Full Query Diagrams	110
	Interpreting Query Diagrams	126
	Simplified Query Diagrams	128
	Exercises	130
6.	Deducing the Best Execution Plan	134
	Robust Execution Plans	134
	Standard Heuristic Join Order	136
	Simple Examples	137
	A Special Case	145
	A Complex Example	147
	Special Rules for Special Cases	151
	Exercise	174
7.	Diagramming and Tuning Complex SQL Queries	176
	Abnormal Join Diagrams	177
	Queries with Subqueries	203
	Queries with Views	216
	Queries with Set Operations	225
	Exercise	227
8.	Why the Diagramming Method Works	228
	The Case for Nested Loops	228
	Choosing the Driving Table	230
	Choosing the Next Table to Join	233
	Summary	236
9.	Special Cases	238
	Outer Joins	238
	Merged Join and Filter Indexes	243
	Missing Indexes	246
	Unfiltered Joins	247
	Unsolvable Problems	248
10.	Outside-the-Box Solutions to Seemingly Unsolvable Problems	250
	When Very Fast Is Not Fast Enough	250
	Queries that Return Data from Too Many Rows	254
	Tuned Queries that Return Few Rows, Slowly	265
A.	Exercise Solutions	269
B.	The Full Process, End to End	282
	Glossary	295
	Index	303