This page documents system variables related to the MyISAM storage engine. For options, see MyISAM Options.
See Server System Variables for a complete list of system variables and instructions on setting them.
See also the Full list of MariaDB options, system and status variables.
key_buffer_size
--key-buffer-size=#
numeric
134217728
8
upwards (upper limit determined by operating system per process limit) key_cache_age_threshold
--key-cache-age-threshold=#
numeric
300
100
to 4294967295
key_cache_block_size
--key-cache-block-size=#
numeric
1024
512
to 16384
key_cache_division_limit
--key-cache-division-limit=#
numeric
100
1
to 100
key_cache_file_hash_size
--key-cache-file-hash-size=#
numeric
512
128
to 16384
MariaDB 10.0.13
key_cache_segments
--key-cache-segments=#
0
(non-segmented) 0
to 64
myisam_block_size
--myisam-block-size=#
numeric
1024
MariaDB 5.2.6
myisam_data_pointer_size
--myisam-data-pointer-size=#
numeric
6
2
to 7
myisam_max_extra_sort_file_size
MySQL 5.0.6
myisam_max_sort_file_size
--myisam-max-sort-file-size=#
numeric
2147483648
9223372036854775807
myisam_mmap_size
--myisam-mmap-size=#
numeric
4294967295
18446744073709547520
7
to 4294967295
7
to 18446744073709547520
MariaDB/MySQL 5.5.1
myisam_recover_options
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. BACKUP
but also backs up the .MYI index file. t.MYI will be saved as t.MYI-datetime.BAK. Added in MariaDB 5.1.51. --myisam-recover-options[=name]
enumeration
BACKUP,QUICK
(>= MariaDB 10.2.4) DEFAULT
(<= MariaDB 10.2.3, >= MariaDB 5.1.44) OFF
(<= MariaDB 5.1.42) OFF
, DEFAULT
, BACKUP
, BACKUP_ALL
, FORCE
or QUICK
myisam_repair_threads
1
, the default, MyISAM table indexes each have their own thread during repair and sorting. Increasing from the default will usually result in faster repair, but will use more CPU and memory. --myisam-repair-threads=#
numeric
1
1
to 4294967295
1
to 18446744073709547520
myisam_sort_buffer_size
--myisam-sort-buffer-size=#
numeric
134217720
(128MB), 8388608
(8MB - before MariaDB 10.0.3) 4096
to 18446744073709547520
myisam_stats_method
nulls_equal
, the default, all NULL index values are treated as a single group. This is usually fine, but if you have large numbers of NULLs the average group size is slanted higher, and the optimizer may miss using the index for ref accesses when it would be useful. If set to nulls_unequal
, the opposite approach is taken, with each NULL forming its own group of one. Conversely, the average group size is slanted lower, and the optimizer may use the index for ref accesses when not suitable. Setting to nulls_ignored
ignores NULLs altogether from index group calculations. See also Index Statistics, aria_stats_method, innodb_stats_method. --myisam-stats-method=name
enumeration
nulls_equal
nulls_equal
, nulls_unequal
, nulls_ignored
myisam_use_mmap
1
(0 is default), memory mapping will be used to reading and writing MyISAM tables. --myisam-use-mmap
boolean
OFF
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Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/myisam-system-variables/