Incompatibilities of CREATE TABLE

This topic describes CREATE TABLE DDL operations that are executed in a MySQL database and can be converted by the DDL synchronization component of OceanBase Migration Service (OMS), but they cannot be executed in the MySQL tenant of OceanBase Database when you migrate data from the MySQL database to the MySQL tenant of OceanBase Database.

Define a generated column based on other generated columns

Use other generated columns in the CREATE TABLE DDL statement to define a newly generated column.

• MySQL databases: supported.

• MySQL tenants of OceanBase Database: not supported.

Example:

CREATE TABLE group_by_t1
(a INT GENERATED ALWAYS AS (1) VIRTUAL,
 b INT GENERATED ALWAYS AS (a) VIRTUAL,
 c INT GENERATED ALWAYS AS (1) VIRTUAL);

Create an index or a constraint

• When you create a constraint, the column types supported in a MySQL database are different from those supported in a MySQL tenant of OceanBase Database. For more information, see Column types that are supported to create indexes or constraints.

• Limitations on creating a FOREIGN KEY constraint:

  • MySQL tenants of OceanBase Database: The referenced column in the parent table must have the UNIQUE KEY or PRIMARY KEY constraint when you create a foreign key.

  • MySQL databases: The referenced column in the parent table must have the UNIQUE KEY, PRIMARY KEY, or KEY constraint when you create a foreign key.