In the data state of INNODB type,

Ibdata is used to store data of files.

The table files in the library name folder are just structures.

Since mysql4. 1 tries innodb by default, this file exists by default.

Innodo's Chinese reference is as follows?

InnoDB startup options?

In order to use the InnoDB table in MySQL-Max-3.23, you must specify the configuration parameters in the [mysqld] area of the configuration file "my.cnf" or "my.ini" (Windows system). As a minimum, in 3.23, you must specify the data file name and size on innodb_data_file_path.

If innodb_data_home_dir is not specified in' my.cnf', a data file will be created in the datadir directory of MySQL. If innodb_data_home_dir is set to an empty string, an absolute path can be given in innodb_data_file_path.

Innodb _ data _ file _ path may not be set in MySQL-4.0: MySQL-4.0 will create a 10 MB automatic extension file' ibdata 1' (in MySQL-4.0.0 and 4.0.65438+) by default.

For better performance, you must explicitly set the InnoDB startup parameters, as shown in the example. Starting from versions 3.23.50 and 4.0.2, InnoDB allows the first data file set in innodb_data_file_path to be described as automatically extended. innodb_data_file_path？

The syntax is as follows: pathtodatafile: size specification; pathtodatafile:size spec； ...？ ...； Pathtodatafile: sizespec [:auto extend [:max: size specification]] If the last data file is described with the autoextend option, then when InnoDB runs out of available table space, the last data file will be automatically extended by 8MB each time.