Syntax:
ALTER TABLESPACE tablespace_name
    {ADD|DROP} DATAFILE 'file_name'
    [INITIAL_SIZE [=] size]
    [WAIT]
    ENGINE [=] engine_name

This statement can be used either to add a new data file, or to drop a
data file from a tablespace.

The ADD DATAFILE variant allows you to specify an initial size using an
INITIAL_SIZE clause, where size is measured in bytes; the default value
is 128M (128 megabytes). You may optionally follow this integer value
with a one-letter abbreviation for an order of magnitude, similar to
those used in my.cnf. Generally, this is one of the letters M (for
megabytes) or G (for gigabytes).

On 32-bit systems, the maximum supported value for INITIAL_SIZE is 4G.
(Bug#29186 (http://bugs.mysql.com/29186))

Once a data file has been created, its size cannot be changed; however,
you can add more data files to the tablespace using additional ALTER
TABLESPACE ... ADD DATAFILE statements.

Using DROP DATAFILE with ALTER TABLESPACE drops the data file
'file_name' from the tablespace. This file must already have been added
to the tablespace using CREATE TABLESPACE or ALTER TABLESPACE;
otherwise an error will result.

Both ALTER TABLESPACE ... ADD DATAFILE and ALTER TABLESPACE ... DROP
DATAFILE require an ENGINE clause which specifies the storage engine
used by the tablespace. In MySQL 5.1, the only accepted values for
engine_name are NDB and NDBCLUSTER.

WAIT is parsed but otherwise ignored, and so has no effect in MySQL
5.1. It is intended for future expansion.

When ALTER TABLESPACE ... ADD DATAFILE is used with ENGINE = NDB, a
data file is created on each Cluster data node. You can verify that the
data files were created and obtain information about them by querying
the INFORMATION_SCHEMA.FILES table. For example, the following query
shows all data files belonging to the tablespace named newts:

mysql> SELECT LOGFILE_GROUP_NAME, FILE_NAME, EXTRA 
    -> FROM INFORMATION_SCHEMA.FILES
    -> WHERE TABLESPACE_NAME = 'newts' AND FILE_TYPE = 'DATAFILE';
+--------------------+--------------+----------------+
| LOGFILE_GROUP_NAME | FILE_NAME    | EXTRA          |
+--------------------+--------------+----------------+
| lg_3               | newdata.dat  | CLUSTER_NODE=3 |
| lg_3               | newdata.dat  | CLUSTER_NODE=4 |
| lg_3               | newdata2.dat | CLUSTER_NODE=3 |
| lg_3               | newdata2.dat | CLUSTER_NODE=4 |
+--------------------+--------------+----------------+
2 rows in set (0.03 sec)

See http://dev.mysql.com/doc/refman/5.1/en/files-table.html.

ALTER TABLESPACE was added in MySQL 5.1.6. In MySQL 5.1, it is useful
only with Disk Data storage for MySQL Cluster. See
http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-disk-data.html.

URL: http://dev.mysql.com/doc/refman/5.1/en/alter-tablespace.html

