5.4.1.2. Specifying the Location of a Tablespace

To create a new InnoDB table in a specific location outside the MySQL data directory, use the DATA DIRECTORY = absolute_path_to_directory clause of the CREATE TABLE statement. (Plan the location in advance, because you cannot use this clause with the ALTER TABLE statement.) The directory you specify could be on another storage device with particular performance or capacity characteristics, such as a fast SSD or a high-capacity HDD.

Within the destination directory, MySQL creates a subdirectory corresponding to the database name, and within that a .ibd file for the new table. In the database directory underneath the MySQL DATADIR directory, MySQL creates a table_name.isl file containing the path name for the table. The .isl file is treated by MySQL like a symbolic link. (Using actual symbolic links has never been supported for InnoDB tables.)

The following example shows how you might run a small development or test instance of MySQL on a laptop with a primary hard drive that is 95% full, and place a new table EXTERNAL on a different storage device with more free space. The shell commands show the different paths to the LOCAL table in its default location under the DATADIR directory, and the EXTERNAL table in the location you specified:

mysql> \! df -k .Filesystem   1024-blocks      Used Available Capacity  iused   ifree %iused  Mounted on/dev/disk0s2   244277768 231603532  12418236    95% 57964881 3104559   95%   /mysql> use test;Database changedmysql> show variables like 'innodb_file_per_table';+-----------------------+-------+| Variable_name         | Value |+-----------------------+-------+| innodb_file_per_table | ON    |+-----------------------+-------+1 row in set (0.00 sec)mysql> \! pwd/usr/local/mysqlmysql> create table local (x int unsigned not null primary key);Query OK, 0 rows affected (0.03 sec)mysql> \! ls -l data/test/local.ibd-rw-rw----  1 cirrus  staff  98304 Nov 13 15:24 data/test/local.ibdmysql> create table external (x int unsigned not null primary key) data directory = '/volumes/external1/data';Query OK, 0 rows affected (0.03 sec)mysql> \! ls -l /volumes/external1/data/test/external.ibd-rwxrwxrwx  1 cirrus  staff  98304 Nov 13 15:34 /volumes/external1/data/test/external.ibdmysql> select count(*) from local;+----------+| count(*) |+----------+|        0 |+----------+1 row in set (0.01 sec)mysql> select count(*) from external;+----------+| count(*) |+----------+|        0 |+----------+1 row in set (0.01 sec)