--key-buffer-size

This is a command-line option for the mariadbd & mysqld commands (arg: Required).

The size of the buffer used for index blocks for MyISAM tables. Increase this to get better index handling (for all reads and multiple writes) to as much as you can afford

See also: Options for mariadbd & mysqld in 10.5 ES, in 10.5 CS, in 10.4 ES, in 10.4 CS, in 10.3 ES, in 10.3 CS, in 10.2 ES, and in 10.2 CS