Connecting WordPress to Database using Unix Domain Socket.

According to a recent study by the Percona team, a significant performance improvement can be achieved when a “Unix Domain Socket” is used instead of a TCP/IP loopback for communication between database and application.

Although in most WordPress tutorials the database connection is made via a TCP/IP loopback, it is also perfectly possible for WordPress to communicate via a Unix Domain Socket, and thus take advantage of the speed gains. Of course, this is provided that the MySQL/MariaDB server is running on the same system and is also available on a Unix Domain Socket.

Use the following command to find the location of the MySQL/MariaDB Unix domain socket:

mysql -e "select @@socket"

This should give you an output similar to this.

+-------------------------+
| @@socket                |
+-------------------------+
| /run/mysqld/mysqld.sock |
+-------------------------+

Now open wp-config.php of your site.

vi /var/www/virtual/example.com/htdocs/wp-config.php

And look for the “DB_HOST” directive which is ether:

define( 'DB_HOST', 'localhost' );

or

define( 'DB_HOST', '127.0.0.1' );

And change it to:

define( 'DB_HOST', 'localhost:/run/mysqld/mysqld.sock' );