MyISAM Storage Engine
MyISAM was the default storage engine from MySQL 3.23 until it was replaced by the InnoDB Storage Engine. We will not use it for any database ourselves but it is still in use by the server internally as default for various tasks, so we set its footprint as small as possible.
# MariaDB Server version 10.2.6
[mysqld]
# MyISAM Storage Engine Configuration
# See https://mariadb.com/kb/en/mariadb/myisam-storage-engine/
#
# Debian/Ubuntu Defaults
#
# Size of the buffer for the index blocks used by MyISAM tables and shared for
# all threads. If you don't use MyISAM tables, you can set key-buffer-size to a
# very low value, like 64K.
# Default: 134217728 (128M)
key_buffer_size = 64K
key_cache_block_size = 512
key_cache_file_hash_size = 128
# MyISAM recovery mode. Multiple options can be selected, comma-delimited. Using
# no argument is equivalent to specifying DEFAULT, while specifying "" is
# equivalent to OFF. If enabled each time the server opens a MyISAM table, it
# checks whether it has been marked as crashed, or wasn't closed properly. If
# so, mysqld will run a check and then attempt to repair the table, writing to
# the error log beforehand.
# Default: BACKUP,QUICK
#myisam_recover_options = BACKUP
# Size in bytes of the buffer allocated when creating or sorting indexes on a
# MyISAM table.
# Default: 134217720 (128MB)
myisam_sort_buffer_size = 4M
# If set to AUTO, MariaDB allows concurrent INSERTs and SELECTs for MyISAM
# tables with no free blocks in the data. If set to NEVER, concurrent inserts
# are disabled. If set to ALWAYS, concurrent inserts are permitted for all
# MyISAM tables, even those with holes, in which case new rows are added at the
# end of a table if the table is being used by another thread. If the --skip-new
# option is used when starting the server, concurrent_insert is set to NEVER.
# Default: AUTO
#concurrent_insert = ALWAYS
# Size in bytes of the buffer used when reading rows from a MyISAM table in
# sorted order after a key sort. Larger values improve ORDER BY performance,
# although rather increase the size by SESSION where the need arises to avoid
# excessive memory use.
# Default: 262144 (256K)
#read_rnd_buffer_size = 1M
# If set, external locking for MyISAM tables is disabled.
# Default: ON
#skip-external-locking = ON
#
# Segmented Key Cache
# https://mariadb.com/kb/en/mariadb/segmented-key-cache/
# The number of segments in a key cache.
# Default: 0
# key_cache_segments = 0