MySQL :: MySQL 8.4 参考手册 :: 18.2.1 MyISAM 启动选项

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MySQL 8.4 参考手册 / 18 个替代存储引擎 / 18.2 MyISAM 存储引擎 / 18.2.1 MyISAM 启动选项

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18.2.1 MyISAM 启动选项18.2.1 MyISAM Startup Options

以下提供给 mysqld 的选项可以用来更改 MyISAM 表的行为。有关更多信息，请参见第 7.1.7 节，“服务器命令选项”。The following options to mysqld can be used to change the behavior of MyISAM tables. For additional information, see Section 7.1.7, “Server Command Options”.

表 18.3 MyISAM 选项及变量参考Table 18.3 MyISAM Option and Variable Reference

名称Name	命令行Cmd-Line	选项文件Option File	系统变量System Var	变量范围Var Scope	动态Dynamic
批量插入缓冲区大小bulk_insert_buffer_size	是Yes	是Yes	是Yes	两者Both	是Yes
并发插入concurrent_insert	是Yes	是Yes	是Yes	全球Global	是Yes
延迟关键字写入delay_key_write	是Yes	是Yes	是Yes	全球Global	是Yes
支持 R 树键have_rtree_keys			是Yes	全球Global	否No
key_buffer_size（键缓冲区大小）key_buffer_size	是Yes	是Yes	是Yes	全球Global	是Yes
ISAM 日志log-isam	是Yes	是Yes
MyISAM 块大小myisam-block-size	是Yes	是Yes
myisam_data_pointer_size	是Yes	是Yes	是Yes	全球Global	是Yes
myisam_max_sort_file_size	是Yes	是Yes	是Yes	全球Global	是Yes
myisam_mmap_size	是Yes	是Yes	是Yes	全球Global	否No
myisam_recover_options	是Yes	是Yes	是Yes	全球Global	否No
myisam_sort_buffer_size	是Yes	是Yes	是Yes	两者Both	是Yes
myisam_stats_method	是Yes	是Yes	是Yes	两者Both	是Yes
myisam_use_mmap	是Yes	是Yes	是Yes	全球Global	是Yes
tmp_table_size（临时表大小）tmp_table_size	是Yes	是Yes	是Yes	两者Both	是Yes

以下系统变量会影响 MyISAM 表的行为。有关更多信息，请参见第 7.1.8 节，“服务器系统变量”。The following system variables affect the behavior of MyISAM tables. For additional information, see Section 7.1.8, “Server System Variables”.

bulk_insert_buffer_size
用于批量插入优化的树缓存大小。The size of the tree cache used in bulk insert optimization.
Note
这是每个线程的限制！This is a limit per thread!
delay_key_write=ALL
在对任何 MyISAM 表进行写入时，不刷新键缓冲区。Don't flush key buffers between writes for any MyISAM table.
Note
如果你这样做，在表正在使用时，不应从另一个程序访问 MyISAM 表（例如从另一个 MySQL 服务器或使用 myisamchk）。这样做有索引损坏的风险。使用 --external-locking 并不能消除此风险。If you do this, you should not access MyISAM tables from another program (such as from another MySQL server or with myisamchk) when the tables are in use. Doing so risks index corruption. Using --external-locking does not eliminate this risk.
myisam_max_sort_file_size
MySQL 在重新创建 MyISAM 索引时（在 REPAIR TABLE、ALTER TABLE 或 LOAD DATA 时）允许使用的临时文件的最大大小。如果文件大小超过此值，则索引将改用键缓存创建，这会更慢。该值以字节为单位。The maximum size of the temporary file that MySQL is permitted to use while re-creating a MyISAM index (during REPAIR TABLE, ALTER TABLE, or LOAD DATA). 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_recover_options=mode
设置自动恢复崩溃的 MyISAM 表的模式。Set the mode for automatic recovery of crashed MyISAM tables.
myisam_sort_buffer_size
设置恢复表时使用的缓冲区大小。Set the size of the buffer used when recovering tables.

如果在启动 mysqld 时设置了 myisam_recover_options 系统变量，则会激活自动恢复。在这种情况下，当服务器打开 MyISAM 表时，它会检查表是否被标记为崩溃，或者表的打开计数变量是否不为 0，并且服务器以禁用外部锁的方式运行。如果上述任一条件为真，将发生以下情况：Automatic recovery is activated if you start mysqld with the myisam_recover_options system variable set. 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:

服务器检查表是否存在错误。The server checks the table for errors.
如果服务器发现错误，它会尝试快速表修复（带排序但不重新创建数据文件）。If the server finds an error, it tries to do a fast table repair (with sorting and without re-creating the data file).
如果由于数据文件中的错误（例如重复键错误）而修复失败，服务器会再次尝试，这次会重新创建数据文件。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.
如果修复仍然失败，服务器会再次尝试使用旧的修复选项方法（逐行写入而不排序）。这种方法应该能够修复任何类型的错误，并且所需磁盘空间较低。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.

如果恢复无法从先前已完成的语句中恢复所有行，并且您没有在 myisam_recover_options 系统变量的值中指定 FORCE，自动修复将中止并在错误日志中显示错误消息：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 system variable, automatic repair aborts with an error message in the error log:

Error: Couldn't repair table: test.g00pages

如果你指定了 FORCE，会写入如下警告：If you specify FORCE, a warning like this is written instead:

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

如果自动恢复值包括 BACKUP，恢复过程会创建名称形式为 tbl_name-datetime.BAK 的文件。你应该有一个 cron 脚本，自动将这些文件从数据库目录移动到备份媒介。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.

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