•For some parameters, override.conf  must be used because systemd itself must know their values and it cannot read MySQL option files to get them. 

•Parameters that specify values otherwise settable only using options known to mysqld_safe  must be specified using systemd because there is no corresponding mysqld  parameter. 

For additional information about using systemd rather than mysqld_safe , see Migrating from mysqld_safe to systemd. 

You can set the following parameters in override.conf : 

•To set the number of file descriptors available to the MySQL server, use LimitNOFILE  in override.conf  rather than the open_files_limit  system variable for mysqld  or --open-files- limit  option for mysqld_safe . 

•To set the maximum core file size, use LimitCore  in override.conf  rather than the --core-file- size  option for mysqld_safe . 

•To set the scheduling priority for the MySQL server, use Nice  in override.conf  rather than the -- nice  option for mysqld_safe . 

Some MySQL parameters are configured using environment variables: 

• LD_PRELOAD : Set this variable if the MySQL server should use a specific memory-allocation library. 

• NOTIFY_SOCKET : This environment variable specifies the socket that mysqld  uses to communicate notification of startup completion and service status change with systemd. It is set by systemd when the mysqld  service is started. The mysqld  service reads the variable setting and writes to the defined location. 

In MySQL 8.0, mysqld  uses the Type=notify  process startup type. ( Type=forking  was used in MySQL 5.7.) With Type=notify , systemd automatically configures a socket file and exports the path to the NOTIFY_SOCKET  environment variable. 

• TZ : Set this variable to specify the default time zone for the server. 

There are multiple ways to specify environment variable values for use by the MySQL server process managed by systemd: 

•Use Environment  lines in the override.conf  file. For the syntax, see the example in the preceding discussion that describes how to use this file. 

•Specify the values in the /etc/sysconfig/mysql  file (create the file if it does not exist). Assign values using the following syntax: 

LD_PRELOAD= /path/to/malloc/library TZ= time_zone_setting 

After modifying /etc/sysconfig/mysql , restart the server to make the changes effective: 

systemctl restart mysqld # RPM platforms systemctl restart mysql # Debian platforms 

To specify options for mysqld  without modifying systemd configuration files directly, set or unset the MYSQLD_OPTS  systemd variable. For example: 

systemctl set-environment MYSQLD_OPTS="--general_log=1" systemctl unset-environment MYSQLD_OPTS 

MYSQLD_OPTS  can also be set in the /etc/sysconfig/mysql  file. 

