MySQL故障排查与优化实战指南

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《MySQL故障排除指南V413HAV》是一本由Svetlana Smirnova编著的专业书籍，专为学习和掌握MySQL数据库的定位、诊断和优化最佳实践而设计。本书旨在帮助读者理解和解决在日常运维中可能遇到的各种MySQL性能问题，确保数据库系统的稳定性和高效性。作者以其丰富的经验和深入的理解，将复杂的故障排查策略分解成易于理解的步骤。书中涵盖了广泛的主题，包括但不限于： 1. **基础诊断**：介绍基本的MySQL监控工具和技术，如SHOW STATUS和EXPLAIN，帮助读者识别查询性能瓶颈。 2. **日志分析**：强调了错误日志、慢查询日志和二进制日志在故障排查中的关键作用，教会读者如何解读这些日志信息以找出问题根源。 3. **索引优化**：详细讲解如何设计和维护有效的索引，以及如何使用ANALYZE TABLE和EXPLAIN来评估索引性能。 4. **存储引擎优化**：比较InnoDB、MyISAM和其他存储引擎的特性，指导用户根据应用场景选择最合适的引擎。 5. **并发控制与锁管理**：阐述了并发操作对数据库性能的影响，以及如何处理死锁和锁定问题。 6. **性能调优策略**：提供了一些实用的优化技巧，如分区表、缓存优化和连接池设置等。 7. **集群和分布式环境**：针对大规模数据库系统，讨论了复制、分片和读写分离等高可用性和扩展性解决方案。 8. **故障恢复与备份管理**：强调备份和恢复流程的重要性，以及如何创建和维护有效的备份策略。 9. **案例研究和实战演练**：通过实际案例展示如何应用所学知识，帮助读者在实际环境中提升问题解决能力。《MySQL故障排除指南》不仅适合数据库管理员和运维工程师，也对系统架构师和开发人员具有参考价值。该书的发布日期是2012年2月，首次修订于同月，不断更新的在线版本可供读者获取最新信息。通过阅读这本书，读者能够提升MySQL数据库的运维技能，有效应对各种挑战，确保系统的稳定运行。

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xiv | Preface

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Acknowledgments

I want to say thank you to the people without whose help this book couldn’t happen.

For a start, this includes my editor, Andy Oram, who did a great job making my English

readable and who showed me gaps and places where I had not described information

in enough detail. He also gave me insight into how prepared my readers would be,

prompting me to add explanations for beginners and to remove trivial things known

by everyone.

I also want to thank the whole MySQL Support Team. These folks share their expertise

and support with every member of the team, and I learned a lot from them. I won’t put

names here, because I want to say “thank you” to all of the people with whom I’ve

worked since joining in 2006, even those who have left and moved to server develop-

ment or another company.

Thanks to Charles Bell, who helped me to start this book. He also did a review of the

book and suggested a lot of improvements. Charles works in the MySQL Replication

and Backup Team at Oracle and is the author of two books about MySQL. Therefore,

his suggestions, both for content and style, were very helpful.

I would also like to thank the people who reviewed the book:

• Shane Bester, my colleague from the MySQL Support Group, who reviewed the

part devoted to his Gypsy program and suggested how to improve the example.

• Alexander (Salle) Keremedarski, who reviewed the whole book and sent me a lot

of great suggestions. Salle has provided MySQL support since its very early days,

starting in the MySQL Support Team and now at SkySQL as Director of EMEA

Support. His knowledge of common user misunderstandings helped me to find

places where I explained things in too little detail, so that a troubleshooting situa-

tion could be read as a best practice when actually it is not.

Preface | xv

• Tonci Grgin, who reviewed the parts about MySQL Connectors and suggested

additions, explaining their behavior. Tonci used to work in the same group as me

and now works in the MySQL Connectors Team. He is the first person I would ask

about anything related to MySQL Connectors.

• Sinisa Milivojevic, who reviewed Chapters 3 and 4 and parts about the MyISAM

check and repairing tools. Sinisa is another reviewer who has worked in MySQL

Support since the very beginning. He was employee #2 in MySQL and still works

in the MySQL Support Team at Oracle. His huge experience is fantastic, and one

might even think he knows every little detail about the MySQL server. Sinisa gave

me insights on some of the topics I discuss and suggested short but very significant

improvements.

• Valeriy Kravchuk, who reviewed Chapters 2 and 4 and the section “InnoDB Mon-

itors” on page 192. He also works in the MySQL Support Team. Valeriy found

many deficiencies in the chapters he reviewed. His criticism forced me to improve

these chapters, although there is always room for development.

• Mark Callaghan, who runs database servers at Facebook, reviewed the whole book.

Mark suggested that I put more examples and further explanation in places that

were not clear. He also suggested examples for Chapter 4 and pointed me to places

where my suggestions can be wrong for certain installations, prompting me to

explain both situations: when the original suggestions fit and when they don’t.

Thanks to Mark, I added more details about these arguable topics.

• Alexey Kopytov also reviewed the whole book. He is the author of the SysBench

utility (which I describe in this book), worked in MySQL Development, and now

works at Percona. Alexey sent me improvements for the SysBench part.

• Dimitri (dim) Kravtchuk, Principal Benchmark Engineer at Oracle, reviewed the

whole book as well. He is also the author of the dim_STAT monitoring solution I

describe in this book, the db_STRESS database benchmarking kit, and a famous

blog where he posts articles about InnoDB performance and MySQL benchmarks.

He suggested several improvements to sections where I describe InnoDB, Perfor-

mance Schema, and hardware impacts.

Finally, thanks to my family:

• My mother, Yulia Ivanovna Ivanova, who showed me how fun engineering can be.

• My parents-in-law, Valentina Alekseevna Lasunova and Nikolay Nikolayevich

Lasunov, who always helped us when we needed it.

• And last but not least, my husband, Sergey Lasunov, who supported me in all my

initiatives.

xvi | Preface

Unfortunately, not all syntax errors are so trivial. I once worked on a trouble ticket

concerning a query like this:

SELECT id FROM t1 WHERE accessible=1;

The problem was a migration issue; the query worked fine in version 5.0 but stopped

working in version 5.1. The problem was that, in version 5.1, “accessible” is a reserved

word. We added quotes (these can be backticks or double quotes, depending on your

SQL mode), and the query started working again:

SELECT `id` FROM `t1` WHERE `accessible`=1;

The actual query looked a lot more complicated, with a large JOIN and a complex

WHERE condition. So the simple error was hard to pick out among all the distractions.

Our first task was to reduce the complex query to the simple one-line SELECT as just

shown, which is an example of a minimal test case. Once we realized that the one-liner

had the same bug as the big, original query, we quickly realized that the programmer

had simply stumbled over a reserved word.

■ The first lesson is to check your query for syntax errors as the first troubleshooting

step.

But what do you do if you don’t know the query? For example, suppose the query was

built by an application. Even more fun is in store when it’s a third-party library that

dynamically builds queries.

Let’s consider this PHP code:

$query = 'SELECT * FROM t4 WHERE f1 IN(';

for ($i = 1; $i < 101; $i ++)

$query .= "'row$i,";

$query = rtrim($query, ',');

$query .= ')';

$result = mysql_query($query);

Looking at the script, it is not easy to see where the error is. Fortunately, we can alter

the code to print the query using an output function. In the case of PHP, this can be

the echo operator. So we modify the code as follows:

…

echo $query;

//$result = mysql_query($query);

Once the program shows us the actual query it’s trying to submit, the problem jumps

right out:

$ php ex1.php

SELECT * FROM t4 WHERE f1 IN('row1,'row2,'row3,'row4,'row5,'row6,'row7,'row8,

'row9,'row10,'row11, 'row12,'row13,'row14,'row15,'row16,'row17,'row18,'row19,'row20)

If you still can’t find the error, try running this query in the MySQL command-line

client:

2 | Chapter 1: Basics

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MySQL故障排查与优化实战指南

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