MyISAM Startup Options
The following options to mysqld can be used to change the behavior of MyISAM tables. For additional information, see , "Server Command Options".
Table 13.12. MyISAM Option/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 |
--myisam-recover-options=modeSet the mode for automatic recovery of crashed
MyISAMtables.--delay-key-write=ALLDon't flush key buffers between writes for any
MyISAMtable.NoteIf you do this, you should not access
MyISAMtables from another program (such as from another MariaDB server or with myisamchk) when the tables are in use. Doing so risks index corruption. Using--external-lockingdoes not eliminate this risk.
The following system variables affect the behavior of MyISAM tables. For additional information, see , "Server System Variables".
bulk_insert_buffer_size
The size of the tree cache used in bulk insert optimization.Note
This is a limit per thread!
myisam_max_sort_file_size
The maximum size of the temporary file that MariaDB is permitted to use while re-creating a
MyISAMindex (duringREPAIR TABLE,ALTER TABLE, orLOAD DATA INFILE). If the file size would be larger than this value, the index is created using the key cache instead, which is slower. The value is given in bytes.myisam_sort_buffer_size
Set the size of the buffer used when recovering tables.
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:
- The server checks the table for errors.
- If the server finds an error, it tries to do a fast table repair (with sorting and without re-creating the data file).
- If the repair fails because of an error in the data file (for example, a duplicate-key error), the server tries again, this time re-creating the data file.
- If the repair still fails, the server tries once more with the old repair option method (write row by row without sorting). This method should be able to repair any type of error and has low disk space requirements.
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
Note that if the automatic recovery value includes BACKUP, the recovery process creates files with names of the form tbl_name-datetime.BAK