Overview|V4.2.4|OceanBase Migration Service|OMS docs|Distributed Database

Overview

Last Updated：2026-04-14 07:36:49 Updated

OceanBase Migration Service (OMS) supports data migration, which allows you to migrate data to or from OceanBase Database in real time from or to other data sources.

Background information

During online data migration, the OMS deployment server must be networked with both the source and target instances. You only need to configure the source and target data sources, select the objects to migrate, and then start the migration task.

OMS automatically completes the entire data migration process. It can replicate database objects, existing data, and incremental data from the source database (table) to the target database (table), and ensure real-time incremental synchronization from the source database to the target database.

Supported migration types

The following table lists the supported migration types.

Migration type	Schema migration	Full migration	Incremental DML	Incremental DDL	Full data verification	Reverse incremental	Tables without primary keys
MySQL -> OB_MySQL	Supported	Supported	Supported	Supported	Supported	Supported	Supported
Oracle-> OB_MySQL	Supported	Supported	Supported	Not supported	Supported	Supported	Supported
TiDB -> OB_MySQL	Supported	Supported	Supported	Not supported	Supported	Supported	Not supported
PostgreSQL -> OB_MySQL	Supported	Supported	Supported	Not supported	Supported	Supported	Not supported
Oracle -> OB_Oracle	Supported	Supported	Supported	Supported	Supported	Supported	Supported
DB2 LUW -> OB_Oracle	Supported	Supported	Supported	Supported	Supported	Supported	Not supported
OB_Oracle -> OB_Oracle	Supported	Supported	Supported	Supported	Supported	Supported	Supported
OB_MySQL -> OB_MySQL	Supported	Supported	Supported	Supported	Supported	Supported	Supported (Not supported in disaster recovery scenarios)
OB_Oracle -> Oracle	Supported	Supported	Supported	Supported	Supported	Supported	Supported
OB_Oracle -> MySQL	Not supported	Not supported	Supported	Not supported	Not supported	Not supported	Not supported
OB_MySQL -> MySQL	Supported	Supported	Supported	Supported	Supported	Supported	Not supported
OB_Oracle -> DB2 LUW	Supported	Supported	Supported	Supported	Supported	Supported	Not supported
DB2 LUW -> OB_MySQL	Supported	Supported	Supported	Supported	Supported	Supported	Not supported
OB_MySQL -> DB2 LUW	Supported	Supported	Supported	Supported	Supported	Supported	Not supported

Migration type descriptions

Migration type	Description
Schema migration	Responsible for migrating data object definitions (tables, indexes, constraints, comments, and views) from the source database to the target database. It automatically filters out temporary tables. When the source database is not OceanBase Database, it converts and assembles data types and SQL syntax based on the syntax standards of the target OceanBase tenant type, then replicates them to the target database.
Full migration	Migrates existing data from source tables to corresponding tables in the target database. You can view the Full Migration page, where you can find the Table Objects, Table Indexes, and Migration Performance. The full migration status will be marked as completed only when both table objects and table indexes are migrated. On the Table Indexes page, click View Creation Syntax after the target table object to view the index creation syntax. Combining full migration with incremental synchronization ensures the final consistency between the source and target databases. If any migration objects fail, the specific failure reasons will be displayed.
Incremental synchronization	After an incremental synchronization task starts, it synchronizes data changes (insertions, modifications, or deletions) from the source database to corresponding tables in the target database. When there is continuous business write operations in the source database, OMS starts the incremental pull module before the full data migration starts. This module pulls incremental updates from the source instance, parses and packages them, and stores them in OMS. After the full data migration is completed, OMS starts the incremental data replay module, which retrieves incremental data from the incremental pull module. The incremental data is filtered, mapped, and converted, then synchronized to the target instance.
Full data verification	After the full data migration is completed and incremental data is synchronized to the target database, OMS automatically initiates a full data verification task for the data tables in the source and target databases. During the incremental data synchronization process, you can also initiate custom data verification. For data that does not match the verification results, you can re-verify all data in the table or only the inconsistent data.
Forward switchover	Forward switchover (abstracted and standardized system cutover process) does not involve switching the application connections. It is a task flow that OMS executes in conjunction with application switching. You need to complete the forward switchover before the application connections are switched to the target database. Forward switchover is an essential process in data migration. It ensures that OMS completes the forward data migration and allows you to start the reverse incremental component based on business needs. The main tasks involved in forward switchover are as follows: You need to confirm that the data migration is completed and wait for the forward synchronization delay to be eliminated. OMS automatically supplements the check constraints and foreign key constraints that were ignored during the schema migration phase when the target database is an Oracle database, an OceanBase database in Oracle-compatible mode, or a DB2 LUW database. OMS automatically deletes the additional hidden columns and unique indexes used for migration. This operation is only performed in data migration tasks between an Oracle database and an OceanBase database, or between OceanBase databases. For more information, see Hidden Column Mechanism in Data Migration Service. You need to supplement the migration of triggers, functions, and stored procedures, which OMS does not support, to the target database. If the data migration task has reverse incremental synchronization, you need to disable the triggers in the source database and delete the foreign key constraints.
Reverse incremental	After the migration is completed, you can initiate a reverse incremental synchronization task from the target database to the source database (reverse) on OMS before the business database is switched. This task synchronizes data changes generated in the target database after the business database is switched back to the source database in real time.

Supported migration types

OMS allows you to migrate data online and synchronize incremental data in real time. The following migration types are supported:

Note

For version limitations on data sources, see Limitations.

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Overview

Background information

Supported migration types

Migration type descriptions

Supported migration types

Note