Drop-In:
/etc/systemd/system/(mysqld/mysql/mariadb).service.d
└─limits.conf
systemctl edit [mysqld|mysql|mariadb]
[Service]
LimitNOFILE=<calculated_value>
systemctl daemon-reload
SHOW VARIABLES LIKE 'open_files_limit';
+------------------+--------+
| Variable_name | Value |
+------------------+--------+
| open_files_limit | 102400 |
+------------------+--------+
1 row in set (0.00 sec)
fs.nr_open=<LimitNOFILE_value>
SHOW VARIABLES LIKE 'open_files_limit';