MariaDB log_error system variable, configuration file difference between Ubuntu 20.04 and 22.04

Ubuntu 20.04 (Focal Fossa)

# dpkg -l | grep mariadb-server-10
ii  mariadb-server-10.3             1:10.3.38-0ubuntu0.20.04.1        amd64        MariaDB database server binaries

# grep -E 'skip_log_error|syslog|log_error' /etc/mysql/ -R | grep -v '#'
/etc/mysql/mariadb.conf.d/50-server.cnf:log_error = /var/log/mysql/error.log
/etc/mysql/mariadb.conf.d/50-mysqld_safe.cnf:skip_log_error
/etc/mysql/mariadb.conf.d/50-mysqld_safe.cnf:syslog

# tail -2 /var/log/mysql/error.log
2023-07-28  8:30:23 0 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.3.38-MariaDB-0ubuntu0.20.04.1'  socket: '/run/mysqld/mysqld.sock'  port: 3306  Ubuntu 20.04

Ubuntu 22.04 (Jammy Jellyfish)

# dpkg -l | grep mariadb-server-10
ii  mariadb-server-10.6             1:10.6.12-0ubuntu0.22.04.1

# grep -E 'skip_log_error|syslog|log_error' /etc/mysql/ -R | grep -v '#'
/etc/mysql/mariadb.conf.d/50-mysqld_safe.cnf:skip_log_error
/etc/mysql/mariadb.conf.d/50-mysqld_safe.cnf:syslog

# tail -2 /var/log/mysql/error.log
tail: cannot open '/var/log/mysql/error.log' for reading: No such file or directory

Up until Ubuntu 22.04, the MariaDB log was written to /var/log/mysql/error.log. Since the log_error system variable has apparently been removed in Ubuntu 22.04 from /etc/mysql/mariadb.conf.d/50-server.cnf, this isn't the case anymore.

• Why was log_error removed from the configuration file /etc/mysql/mariadb.conf.d/50-server.cnf?
• Why was the log file /var/log/mysql/error.log still created in Ubuntu 20.04, even though skip_log_error was used by default?
  • I assume this is due to the order in which the configuration files are processed, if so, where can I see this?

Side note
The log file did not exist before MariaDB was installed.

# ls /var/log/mysql/error.log
ls: cannot access '/var/log/mysql/error.log': No such file or directory
# dpkg -l | grep mariadb-server-10
# apt install mariadb-server
(...)
# dpkg -l | grep mariadb-server-10
ii  mariadb-server-10.3             1:10.3.38-0ubuntu0.20.04.1        amd64        MariaDB database server binaries
# ls /var/log/mysql/error.log
/var/log/mysql/error.log

Are you sure you didn't set log_error before in the past?

In mariadb select the variable to see the value:

select @@log_error

For as long as I can remember systemd being used, log_error has defauled to no value so the error log is written to STDOUT/STDERR so systemd can catch it.

You can still read the log data with journalctl:

journalctl -u mariadb.service

EDIT: looking at that file, it can be ignored:

$ cat /etc/mysql/mariadb.conf.d/50-mysqld_safe.cnf
# NOTE: THIS FILE IS READ ONLY BY THE TRADITIONAL SYSV INIT SCRIPT, NOT SYSTEMD.
# MARIADB SYSTEMD DOES _NOT_ UTILIZE MYSQLD_SAFE NOR READ THIS FILE.
#
# For similar behavior, systemd users should create the following file:
# /etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf
#
# To achieve the same result as the default 50-mysqld_safe.cnf, please create
# /etc/systemd/system/mariadb.service.d/migrated-from-my.cnf-settings.conf
# with the following contents:
# [Service]
# User = mysql
# StandardOutput = syslog
# StandardError = syslog
# SyslogFacility = daemon
# SyslogLevel = err
# SyslogIdentifier = mysqld
#
# For more information, please read https://mariadb.com/kb/en/mariadb/systemd/