MySQL Data Directory

Summary: in this tutorial, you will learn about MySQL data directory. We’ll cover its default location, and configuration, and share some best practices for effective management.

Introduction to MySQL Data Directory

MySQL data directory stores the databases, tables, log files, and other essential elements that enable the functioning of the MySQL Server.

Default location

When installing MySQL, you can explicitly set the location for the data directory.

If you use the default, the data directory location depends on the operating system where you install MySQL Server as illustrated in the following table:

Configuration File

MySQL stores the location of the data directory in the MySQL configuration file (my.cnf or my.ini). For example:

[mysqld]
datadir=/var/lib/mysql/Code language: JavaScript (javascript)

To check the current location of the data directory using the mysql program, you can follow these steps:

First, connect to the MySQL Server:

mysql -u root -p

Second, display the value of the @@datadir system variable:

SELECT @@datadir;Code language: CSS (css)

Here’s the output on Linux and macOS:

+-----------------+
| @@datadir       |
+-----------------+
| /var/lib/mysql/ |
+-----------------+
1 row in set (0.00 sec)Code language: JavaScript (javascript)

The output on Windows will look like this:

+---------------------------------------------+
| @@datadir                                   |
+---------------------------------------------+
| C:\ProgramData\MySQL\MySQL Server 8.0\Data\ |
+---------------------------------------------+
1 row in set (0.00 sec)Code language: JavaScript (javascript)

Contents

The following are the contents of the data directory:

• Databases: MySQL stores each database in a separate subdirectory within the data directory.
• Tables: MySQL stores tables and their associated data files within the respective database directories.
• Log Files: MySQL uses various log files (e.g., error log, binary log) to record events and transactions.
• Temporary Files: The tmp directory manages temporary tables and other temporary storage requirements.

Security

Typically, when setting up MySQL, the MySQL installer creates a user called mysql and assigns its home directory to the data directory, commonly found at /var/lib/mysql/.

The mysql user is granted the appropriate permissions to access the directories and files in the data directory.

Summary

• MySQL data directory is an important directory that stores databases, tables, log files, and other essential data for the MySQL database server.