The previous version was 5.7.19.
My dedicated server is still running on CentOS 6.x, and I had just to enable the MySQL Community 8.0 yum repository and upgrade the rpms:
# yum update mysql-community-server --enablerepo=mysql80-community
After the upgrade, I had to modify my.cnf to remove the lines related to the non regretted Query Cache:
After this, I could start
mysqld and run
I tried to connect with the command line client and it worked perfectly.
Then, I wanted to remove the maintenance mode on lefred.be but WordPress returned me an error that it couldn’t connect to the database:
I verified the mysql error log, nothing wrong (bad credentials are logged), and no error in the apache’s log.
I decided to run WordPress in debug mode :
Then I could see this error message that sounded familiar:
Warning: mysqli_real_connect(): Server sent charset (255) unknown to the client. Please, report to the developers in /var/…/www/wp-includes/wp-db.php on line 1548
I modified again
my.cnf to add the following line under
collation-server = utf8mb4_general_ci
After a restart of mysqld, everything went back normal !
The MySQL connector used on my system for PHP is
Name : php55w-mysqlnd Arch : x86_64 Version : 5.5.38 Release : 1.w6 Size : 956 k Repo : installed From repo : webtatic Summary : A module for PHP applications that use MySQL databases URL : http://www.php.net/ License : PHP Description : The php-mysqlnd package contains a dynamic shared object that will add : MySQL database support to PHP. MySQL is an object-relational database : management system. PHP is an HTML-embeddable scripting language. If : you need MySQL support for PHP applications, you will need to install : this package and the php package. : : This package use the MySQL Native Driver
The next post will be related to the workload analysis using performance_schema & sys and see if something can be improved.