Table Maintenance Statements CHECK TABLE  works for  InnoDB ,  MyISAM ,  ARCHIVE , and  CSV  tables. Before running  CHECK TABLE  on  InnoDB  tables, see CHECK TABLE Usage Notes for InnoDB Tables. CHECK TABLE  is supported for partitioned tables, and you can use  ALTER TABLE ... CHECK PARTITION  to check one or more partitions; for more information, see Section 13.1.9, “ALTER TABLE Statement” , and Section 24.3.4, “Maintenance of Partitions” . CHECK TABLE  ignores virtual generated columns that are not indexed. •CHECK TABLE Output •Checking Version Compatibility •Checking Data Consistency •CHECK TABLE Usage Notes for InnoDB Tables •CHECK TABLE Usage Notes for MyISAM Tables CHECK TABLE Output Checking Version Compatibility CHECK TABLE  returns a result set with the columns shown in the following table. The statement might produce many rows of information for each checked table. The last row has a Msg_type  value of  status  and the  Msg_text  normally should be  OK .  Table is already up to date  means that the storage engine for the table indicated that there was no need to check the table. Column Value Table The table name Op Always  check Msg_type status ,  error ,  info ,  note , or  warning Msg_text An informational message The  FOR UPGRADE  option checks whether the named tables are compatible with the current version of MySQL. With  FOR UPGRADE , the server checks each table to determine whether there have been any incompatible changes in any of the table’s data types or indexes since the table was created. If not, the check succeeds. Otherwise, if there is a possible incompatibility, the server runs a full check on the table (which might take some time). Incompatibilities might occur because the storage format for a data type has changed or because its sort order has changed. Our aim is to avoid these changes, but occasionally they are necessary to correct problems that would be worse than an incompatibility between releases. FOR UPGRADE  discovers these incompatibilities: •The indexing order for end-space in  TEXT  columns for  InnoDB  and  MyISAM  tables changed between MySQL 4.1 and 5.0. •The storage method of the new  DECIMAL  data type changed between MySQL 5.0.3 and 5.0.5. •Changes are sometimes made to character sets or collations that require table indexes to be rebuilt. For details about such changes, see Section 2.11.4, “Changes in MySQL 8.0” . For information about rebuilding tables, see Section 2.11.13, “Rebuilding or Repairing Tables or Indexes” . 2891