Supported DDL operations in incremental migration between MySQL tenants of OceanBase Database

You can use DDL operations to migrate incremental data between MySQL tenants of OceanBase Database.

Notice

If you have created an index in the source tenant, it also exists in the destination tenant. OMS Community Edition automatically ignores the index without interrupting the migration process.

Supported DDL operations in incremental migration

• ALTER TABLE ADD COLUMN

• ALTER TABLE MODIFY COLUMN

  > **Notice**
  >
  > You can only extend the column length. You cannot modify the column type.
  

• ALTER TABLE ALTER COLUMN SET DEFAULT and ALTER TABLE ALTER COLUMN DROP DEFAULT

• ALTER TABLE DROP COLUMN

• CREATE TABLE

• DROP TABLE

• TRUNCATE TABLE

• CREATE INDEX and ALTER TABLE ADD INDEX

• DROP INDEX and ALTER TABLE DROP INDEX

• RENAME TABLE and ALTER TABLE RENAME

Limits of DDL operations in incremental migration

• If a table to be synchronized involves DDL operations that are not supported, the migration link may be interrupted and unrecoverable data exceptions may be caused.

• Frequent DDL operations on a table are not supported. After the store finishes a DDL operation, which can be determined based on the timestamp, it proceeds to the next DDL operation. Otherwise, the store may exit unexpectedly or cause unrecoverable data exceptions.

• Make sure that no DDL operations are performed before you create a store and when a store is being started. If log pulling is involved, make sure that no DDL operations are performed during the period from the start time when logs are pulled to the current time. Otherwise, the store may exit unexpectedly or cause unrecoverable data exceptions.

• The table names before and after the RENAME TABLE statement must be both included or both not included in the list of tables to be synchronized.

• If you enable DDL operations in incremental migration, the DROP INDEX command is executed on all indexes, which may cause index loss in the destination database.