Synchronize DDL operations from an Oracle tenant of OceanBase Database to an Oracle database

Supported DDL operations

• CREATE TABLE

   You can create partitioned tables but cannot use `CREATE TABLE AS SELECT` to create tables.
  

• DROP TABLE

• TRUNCATE TABLE

• ADD PARTITION

   You can add partitions and subpartitions by using RANGE or LIST partitioning. HASH partitioning is not supported.
  

• DROP PARTITION

   You can drop one or more partitions and subpartitions.
  

• TRUNCATE PARTITION

   You can truncate one or more partitions and subpartitions.
  

• RENAME TABLE and ALTER TABLE RENAME

• ALTER TABLE ADD COLUMN

• ALTER TABLE MODIFY COLUMN

  Notice

  You can increase the column length, but you cannot modify the column type.

• CREATE INDEX

• DROP INDEX

• Adding or dropping comments on tables or columns

Limitations

• Only DDL operations listed in the preceding section are supported. If the table to be synchronized involves other types of DDL operations, the data migration project may fail and cause unrecoverable data exceptions.

• 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 delete an unnamed primary key, the corresponding constraint whose name starts with SYS_C in the Oracle database is deleted. If you perform inter-database data migration or synchronization, for example, from an Oracle database to an OceanBase database, the primary keys in the OceanBase database cannot be deleted because they are different from those in the Oracle database.

• When you migrate data from an Oracle tenant of OceanBase Database to an Oracle database, you cannot perform a DDL operation that changes a table with a primary key to a table without a primary key.

  • If a table in the Oracle tenant of OceanBase Database has a primary key, all DDL operations are supported.

  • If a table in the Oracle tenant of OceanBase Database has only a not-null unique key, a DDL operation that removes the not-null unique key is not supported.

• A table creation DDL operation that involves the CASE WHEN INDEX clause cannot be synchronized.

• If you enable DDL synchronization, the index dropped in the source database by executing the drop index statement is also dropped in the destination database. This may cause index loss in the destination database.