MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6

15.2.1 MyISAM Startup Options

The following options to mysqld can be used to change the behavior of MyISAM tables. For additional information, see Section 5.1.6, “Server Command Options”.

Table 15.3 MyISAM Option and Variable Reference

Name Cmd-Line Option File System Var Status Var Var Scope Dynamic
bulk_insert_buffer_size Yes Yes Yes Both Yes
concurrent_insert Yes Yes Yes Global Yes
delay-key-write Yes Yes Global Yes
- Variable: delay_key_write Yes Global Yes
have_rtree_keys Yes Global No
key_buffer_size Yes Yes Yes Global Yes
log-isam Yes Yes
myisam-block-size Yes Yes
myisam_data_pointer_size Yes Yes Yes Global Yes
myisam_max_sort_file_size Yes Yes Yes Global Yes
myisam_mmap_size Yes Yes Yes Global No
myisam-recover-options Yes Yes
- Variable: myisam_recover_options
myisam_recover_options Yes Global No
myisam_repair_threads Yes Yes Yes Both Yes
myisam_sort_buffer_size Yes Yes Yes Both Yes
myisam_stats_method Yes Yes Yes Both Yes
myisam_use_mmap Yes Yes Yes Global Yes
skip-concurrent-insert Yes Yes
- Variable: concurrent_insert
tmp_table_size Yes Yes Yes Both Yes

The following system variables affect the behavior of MyISAM tables. For additional information, see Section 5.1.7, “Server System Variables”.

Automatic recovery is activated if you start mysqld with the --myisam-recover-options option. In this case, when the server opens a MyISAM table, it checks whether the table is marked as crashed or whether the open count variable for the table is not 0 and you are running the server with external locking disabled. If either of these conditions is true, the following happens:

If the recovery wouldn't be able to recover all rows from previously completed statements and you didn't specify FORCE in the value of the --myisam-recover-options option, automatic repair aborts with an error message in the error log:

Error: Couldn't repair table: test.g00pages

If you specify FORCE, a warning like this is written instead:

Warning: Found 344 of 354 rows when repairing ./test/g00pages

If the automatic recovery value includes BACKUP, the recovery process creates files with names of the form tbl_name-datetime.BAK. You should have a cron script that automatically moves these files from the database directories to backup media.