Prior to NDB 8.0.21, the table comment used with ALTER TABLE  replaced any existing comment which the table might have had. This meant that (for example) the READ_BACKUP  value was not carried over to the new comment set by the ALTER TABLE  statement, and that any unspecified values reverted to their defaults. (BUG#30428829) There was thus no longer any way using SQL to retrieve the value previously set for the comment. To keep comment values from reverting to their defaults, it was necessry to preserve any such values from the existing comment string and include them in the comment passed to ALTER TABLE . 

You can also see the value of the PARTITION_BALANCE  option in the output of ndb_desc . ndb_desc also shows whether the READ_BACKUP  and FULLY_REPLICATED  options are set for the table. See the description of this program for more information. 

## 13.1.21 CREATE TABLESPACE Statement 

CREATE [UNDO] TABLESPACE tablespace_name InnoDB and NDB: [ADD DATAFILE ’ file_name ’] [AUTOEXTEND_SIZE [=] value ] InnoDB only: [FILE_BLOCK_SIZE = value] [ENCRYPTION [=] {’Y’ | ’N’}] NDB only: USE LOGFILE GROUP logfile_group [EXTENT_SIZE [=] extent_size ] [INITIAL_SIZE [=] initial_size ] [MAX_SIZE [=] max_size ] [NODEGROUP [=] nodegroup_id ] [WAIT] [COMMENT [=] ’ string ’] InnoDB and NDB: [ENGINE [=] engine_name ] Reserved for future use: [ENGINE_ATTRIBUTE [=] ’ string ’] 

This statement is used to create a tablespace. The precise syntax and semantics depend on the storage engine used. In standard MySQL releases, this is always an InnoDB  tablespace. MySQL NDB Cluster also supports tablespaces using the NDB  storage engine. 

## Considerations for InnoDB 

•Considerations for InnoDB 

•Considerations for NDB Cluster 

•Options 

•Notes 

•InnoDB Examples 

•NDB Example 

CREATE TABLESPACE  syntax is used to create general tablespaces or undo tablespaces. The UNDO keyword, introduced in MySQL 8.0.14, must be specified to create an undo tablespace. 

