Syntax:
CREATE LOGFILE GROUP logfile_group
    ADD UNDOFILE 'undo_file'
    [INITIAL_SIZE [=] initial_size]
    [UNDO_BUFFER_SIZE [=] undo_buffer_size]
    [REDO_BUFFER_SIZE [=] redo_buffer_size]
    [NODEGROUP [=] nodegroup_id]
    [WAIT]
    [COMMENT [=] comment_text]
    ENGINE [=] engine_name

This statement creates a new log file group named logfile_group having
a single UNDO file named 'undo_file'. A CREATE LOGFILE GROUP statement
has one and only one ADD UNDOFILE clause. For rules covering the naming
of log file groups, see
http://dev.mysql.com/doc/refman/5.1/en/identifiers.html.

*Note*: All MySQL Cluster Disk Data objects share the same namespace.
This means that each Disk Data object must be uniquely named (and not
merely each Disk Data object of a given type). For example, you cannot
have a tablespace and a log file group with the same name, or a
tablespace and a data file with the same name.

Beginning with MySQL 5.1.8, you can have only one log file group per
Cluster at any given time. (See Bug #16386)

Prior to MySQL Cluster NDB 6.2.17, 6.3.23, and 6.4.3, path and file
names for undo log files could not be longer than 128 characters. (Bug
#31769)

The optional INITIAL_SIZE parameter sets the UNDO file's initial size;
if not specified, it defaults to 128M (128 megabytes). The optional
UNDO_BUFFER_SIZE parameter sets the size used by the UNDO buffer for
the log file group; The default value for UNDO_BUFFER_SIZE is 8M (eight
megabytes); this value cannot exceed the amount of system memory
available. Both of these parameters are specified in bytes. You may
optionally follow either or both of these 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).

The memory used for both INITIAL_SIZE and UNDO_BUFFER_SIZE comes from
the global pool whose size is determined by the value of the
SharedGlobalMemory data node configuration parameter. This includes any
default value implied for these options by the setting of the
InitialLogFileGroup data node configuration parameter.

Beginning with MySQL Cluster NDB 6.2.17, 6.3.23, and 6.4.3, the maximum
permitted for UNDO_BUFFER_SIZE is 600M; previously, it was 150M. (Bug
#34102)

On 32-bit systems, the maximum supported value for INITIAL_SIZE is 4G.
(Bug #29186)

Beginning with MySQL Cluster NDB 2.1.18, 6.3.24, and 7.0.4, the minimum
permitted value for INITIAL_SIZE is 1M. (Bug #29574)

The ENGINE option determines the storage engine to be used by this log
file group, with engine_name being the name of the storage engine. In
MySQL 5.1, this must be NDB (or NDBCLUSTER). If ENGINE is not set,
MySQL tries to use the engine specified by the storage_engine server
system variable. In any case, if the engine is not specified as NDB or
NDBCLUSTER, the CREATE LOGFILE GROUP statement appears to succeed but
actually fails to create the log file group, as shown here:

mysql> CREATE LOGFILE GROUP lg1 
    ->     ADD UNDOFILE 'undo.dat' INITIAL_SIZE = 10M;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql> SHOW WARNINGS;
+-------+------+------------------------------------------------------------------------------------------------+
| Level | Code | Message                                                                                        |
+-------+------+------------------------------------------------------------------------------------------------+
| Error | 1478 | Table storage engine 'MyISAM' does not support the create option 'TABLESPACE or LOGFILE GROUP' |
+-------+------+------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> DROP LOGFILE GROUP lg1 ENGINE = NDB;              
ERROR 1529 (HY000): Failed to drop LOGFILE GROUP

mysql> CREATE LOGFILE GROUP lg1 
    ->     ADD UNDOFILE 'undo.dat' INITIAL_SIZE = 10M
    ->     ENGINE = NDB;
Query OK, 0 rows affected (2.97 sec)

The fact that the CREATE LOGFILE GROUP statement does not actually
return an error when a non-NDB storage engine is named, but rather
appears to succeed, is a known issue which we hope to address in a
future release of MySQL Cluster.

REDO_BUFFER_SIZE, NODEGROUP, WAIT, and COMMENT are parsed but ignored,
and so have no effect in MySQL 5.1. These options are intended for
future expansion.

When used with ENGINE [=] NDB, a log file group and associated UNDO log
file are created on each Cluster data node. You can verify that the
UNDO files were created and obtain information about them by querying
the INFORMATION_SCHEMA.FILES table. For example:

mysql> SELECT LOGFILE_GROUP_NAME, LOGFILE_GROUP_NUMBER, EXTRA
    -> FROM INFORMATION_SCHEMA.FILES
    -> WHERE FILE_NAME = 'undo_10.dat';
+--------------------+----------------------+----------------+
| LOGFILE_GROUP_NAME | LOGFILE_GROUP_NUMBER | EXTRA          |
+--------------------+----------------------+----------------+
| lg_3               |                   11 | CLUSTER_NODE=3 |
| lg_3               |                   11 | CLUSTER_NODE=4 |
+--------------------+----------------------+----------------+
2 rows in set (0.06 sec)

CREATE LOGFILE GROUP 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/create-logfile-group.html

