ALTER LOGFILE GROUP Statement ADD UNDOFILE ’ file_name ’ [INITIAL_SIZE [=]  size ] [WAIT] ENGINE [=]  engine_name This statement adds an  UNDO  file named ’ file_name ’ to an existing log file group  logfile_group . An ALTER LOGFILE GROUP  statement has one and only one  ADD UNDOFILE  clause. No  DROP UNDOFILE clause is currently supported. All NDB 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 an undo log file with the same name, or an undo log file and a data file with the same name. Note The optional  INITIAL_SIZE  parameter sets the  UNDO  file’s initial size in bytes; if not specified, the initial size defaults to 134217728 (128 MB). You may optionally follow  size  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  (megabytes) or G  (gigabytes). (Bug #13116514, Bug #16104705, Bug #62858) On 32-bit systems, the maximum supported value for  INITIAL_SIZE  is 4294967296 (4 GB). (Bug #29186) The minimum allowed value for  INITIAL_SIZE  is 1048576 (1 MB). (Bug #29574) WAIT  is parsed but otherwise ignored. This keyword currently has no effect, and is intended for future expansion. The  ENGINE  parameter (required) determines the storage engine which is used by this log file group, with  engine_name  being the name of the storage engine. Currently, the only accepted values for engine_name  are “ NDBCLUSTER ”  and “ NDB ” . The two values are equivalent. Here is an example, which assumes that the log file group  lg_3  has already been created using  CREATE LOGFILE GROUP  (see Section 13.1.16, “CREATE LOGFILE GROUP Statement” ): Note ALTER LOGFILE GROUP lg_3 ADD UNDOFILE ’undo_10.dat’ INITIAL_SIZE=32M ENGINE=NDBCLUSTER; When  ALTER LOGFILE GROUP  is used with  ENGINE = NDBCLUSTER  (alternatively,  ENGINE = NDB ), an UNDO  log file is created on each NDB 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 FILE_NAME, LOGFILE_GROUP_NUMBER, EXTRA ->  FROM INFORMATION_SCHEMA.FILES ->  WHERE LOGFILE_GROUP_NAME = ’lg_3’; (See Section 26.3.15, “The INFORMATION_SCHEMA FILES Table” .) 2480 +-------------+----------------------+----------------+ | FILE_NAME | LOGFILE_GROUP_NUMBER | EXTRA | +-------------+----------------------+----------------+ | newdata.dat | 0 | CLUSTER_NODE=3 | | newdata.dat | 0 | CLUSTER_NODE=4 | | undo_10.dat | 11 | CLUSTER_NODE=3 | | undo_10.dat | 11 | CLUSTER_NODE=4 | +-------------+----------------------+----------------+ 4 rows in set (0.01 sec)