Book Image

MySQL 8 Cookbook

By : Karthik Appigatla
Book Image

MySQL 8 Cookbook

By: Karthik Appigatla

Overview of this book

MySQL is one of the most popular and widely used relational databases in the World today. The recently released MySQL 8 version promises to be better and more efficient than ever before. This book contains everything you need to know to be the go-to person in your organization when it comes to MySQL. Starting with a quick installation and configuration of your MySQL instance, the book quickly jumps into the querying aspects of MySQL. It shows you the newest improvements in MySQL 8 and gives you hands-on experience in managing high-transaction and real-time datasets. If you've already worked with MySQL before and are looking to migrate your application to MySQL 8, this book will also show you how to do that. The book also contains recipes on efficient MySQL administration, with tips on effective user management, data recovery, security, database monitoring, performance tuning, troubleshooting, and more. With quick solutions to common and not-so-common problems you might encounter while working with MySQL 8, the book contains practical tips and tricks to give you the edge over others in designing, developing, and administering your database effectively.
Table of Contents (20 chapters)
Title Page
Dedication
Packt Upsell
Contributors
Preface
Index

The explain plan


How MySQL executes queries is one of the major factors of database performance. You can verify the MySQL execution plan using the EXPLAIN command. Starting from MySQL 5.7.2, you can use EXPLAIN to examine queries currently executing in other sessions. EXPLAIN FORMAT=JSON gives detailed information.

How to do it...

Let's get into the details.

Using EXPLAIN

The explain plan gives information on how the optimizer is going to execute the query. You just need to prefix the EXPLAIN keyword to the query:

mysql> EXPLAIN SELECT dept_name FROM dept_emp JOIN employees ON dept_emp.emp_no=employees.emp_no JOIN departments ON departments.dept_no=dept_emp.dept_no WHERE employees.first_name='Aamer'\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: employees
   partitions: NULL
         type: ref
possible_keys: PRIMARY,name
          key: name
      key_len: 58
          ref: const
         rows: 228
     filtered: 100.00...