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

Using global and session variables


As you have seen in the previous chapters, you can set the parameters by connecting to MySQL and executing the SET command.

There are two types of variables based on the scope of the variable:

  • Global: Applies to all the new connections
  • Session: Applies only to the current connection (session)

How to do it...

For example, if you want to log all queries that are slower than one second, you can execute:

mysql> SET GLOBAL long_query_time = 1;

To make the changes persistent across restarts use:

mysql> SET PERSIST long_query_time = 1;
Query OK, 0 rows affected (0.01 sec)

Or:

mysql> SET @@persist.long_query_time = 1;
Query OK, 0 rows affected (0.00 sec)

The persisted global system variable settings are stored in mysqld-auto.cnf which is located in data directory.

Suppose you want to log queries only for this session and not for all the connections. You can use the following command:

mysql> SET SESSION long_query_time = 1;