ApsaraDB RDS for MySQL does not support the MyISAM storage engine because of the following reasons:
The data integrity protection mechanism of MyISAM has defects. These defects may cause data corruption or data loss. In addition, most of these defects are design issues and cannot be fixed without compromising compatibility.
If your data stored in MyISAM is corrupted, you must manually restore most of the corrupted data.
MyISAM is not the optimal storage solution for ApsaraDB RDS for MySQL in terms of I/O operations. Therefore, MyISAM does not have significant performance advantages over InnoDB.
Data can be migrated from MyISAM to InnoDB at a low cost. For most applications, you need to only modify the table creation code to complete the migration.
The preference on MyISAM is shifting to InnoDB. In MySQL 5.7 and MySQL 8.0, you can choose not to use MyISAM. The system data management is also transferred to InnoDB.