myisamchk — MyISAM Table-Maintenance Utility Variable Default Value read_buffer_size 262136 sort_buffer_size 2097144 sort_key_blocks 16 stats_method nulls_unequal write_buffer_size 262136 The possible  myisamchk  variables and their default values can be examined with  myisamchk --help : myisam_sort_buffer_size  is used when the keys are repaired by sorting keys, which is the normal case when you use  --recover .  sort_buffer_size  is a deprecated synonym for myisam_sort_buffer_size . key_buffer_size  is used when you are checking the table with  --extend-check  or when the keys are repaired by inserting keys row by row into the table (like when doing normal inserts). Repairing through the key buffer is used in the following cases: •You use  --safe-recover . •The temporary files needed to sort the keys would be more than twice as big as when creating the key file directly. This is often the case when you have large key values for  CHAR ,  VARCHAR , or  TEXT columns, because the sort operation needs to store the complete key values as it proceeds. If you have lots of temporary space and you can force  myisamchk  to repair by sorting, you can use the  --sort- recover  option. Repairing through the key buffer takes much less disk space than using sorting, but is also much slower. If you want a faster repair, set the  key_buffer_size  and  myisam_sort_buffer_size  variables to about 25% of your available memory. You can set both variables to large values, because only one of them is used at a time. myisam_block_size  is the size used for index blocks. stats_method  influences how  NULL  values are treated for index statistics collection when the  -- analyze  option is given. It acts like the  myisam_stats_method  system variable. For more information, see the description of  myisam_stats_method  in Section 5.1.8, “Server System Variables” , and Section 8.3.8, “InnoDB and MyISAM Index Statistics Collection” . ft_min_word_len  and  ft_max_word_len  indicate the minimum and maximum word length for FULLTEXT  indexes on  MyISAM  tables.  ft_stopword_file  names the stopword file. These need to be set under the following circumstances. If you use  myisamchk  to perform an operation that modifies table indexes (such as repair or analyze), the FULLTEXT  indexes are rebuilt using the default full-text parameter values for minimum and maximum word length and the stopword file unless you specify otherwise. This can result in queries failing. The problem occurs because these parameters are known only by the server. They are not stored in MyISAM  index files. To avoid the problem if you have modified the minimum or maximum word length or the stopword file in the server, specify the same  ft_min_word_len ,  ft_max_word_len , and ft_stopword_file  values to  myisamchk  that you use for  mysqld . For example, if you have set the minimum word length to 3, you can repair a table with  myisamchk  like this: myisamchk --recover --ft_min_word_len=3  tbl_name .MYI 567