OceanBase Migration Service (OMS) provides the data migration feature to help you migrate data between OceanBase Database and other data sources in real time.
Background information
OMS supports online migration. The server deployed with OMS must be able to connect to both source and destination database instances at the same time. You can start a data migration task simply after you configure the source and destination databases and select the objects to be migrated.
OMS automatically performs all the procedures in a data migration task, replicating the database objects, existing data, or incremental data in the source database (data table) to the destination database (data table). It also ensures the real-time synchronization of incremental data from the source database to the destination database.
Supported migration processes
OMS provides online data migration and real-time incremental data synchronization. The following migration processes are supported:
Migrate data from a MySQL database to a MySQL tenant of OceanBase Database
Migrate data from a MySQL tenant of OceanBase Database to a MySQL database
Migrate data from an Oracle database to a MySQL tenant of OceanBase Database
Migrate data from an Oracle tenant of OceanBase Database to an Oracle database
Migrate data from an Oracle database to an Oracle tenant of OceanBase Database
Migrate data from a DB2 LUW database to an Oracle tenant of OceanBase Database
Migrate data from an Oracle tenant of OceanBase Database to a DB2 LUW database
Migrate data from a DB2 LUW database to a MySQL tenant of OceanBase Database
Migrate data from a MySQL tenant of OceanBase Database to a DB2 LUW database
Migrate data within OceanBase Database in active-active disaster recovery scenarios
Migrate data from a TiDB database to a MySQL tenant of OceanBase database
Migrate data from a PostgreSQL database to a MySQL tenant of OceanBase Database.
Note:
For more information about the version restrictions on data sources, see Limits.
OMS V1.4.4 supports data migration between more types of databases. For more information, see the product documentation for OMS V1.4.4.
Supported migration types
For more information about the operations for each type of data migration project, see Start a data migration project.
| Migration type | Description |
|---|---|
| Schema migration | The migration of the definitions of data objects (tables, indexes, constraints, comments, and views) from the source database to the destination OceanBase database. Temporary tables are automatically filtered out. If the source database is not an OceanBase database, OMS performs format conversion and encapsulation based on the syntax definition and standard of the tenant type of the destination OceanBase database, and then OMS replicates the data to the destination OceanBase database. |
| Full migration | The migration of the existing data from tables in the source database to corresponding tables in the OceanBase database. You can view table objects and table indexes on the Full Migration page. The status of the full migration changes to Completed only after migration of the table objects and table indexes is completed. On the Table Indexes page, you can click View Creation Syntax next to the target table object to view its index creation syntax. You can combine full migration with incremental migration to ensure data consistency between the source and destination databases. If any objects failed to be migrated during a full migration, the causes of the failure are displayed. |
| Incremental migration | The migration of changed data of the source database to the corresponding table in OceanBase Database. Data changes include data addition, modification, and deletion. When services are continuously writing data to the source database, OMS starts the incremental data pull module to pull incremental data from the source instance, parses and encapsulates the incremental data, and then stores the data in OMS, before it starts the full data migration. After a full data migration task is completed, OMS starts the incremental data replay module to pull incremental data from the incremental data pull module. The incremental data is synchronized to the destination instance after being filtered, mapped, and converted. |
| Full verification | After the full data migration and incremental data migration are completed, OMS automatically initiates a full data verification task to verify the data tables in the source database and the tables in the destination database. OMS also provides corresponding APIs for you to initiate custom data verification tasks in the incremental data synchronization process. You can view the information of specific columns where inconsistent data is detected. OMS runs SQL scripts to correct the data in the destination database based on the data in the source database. The correction operation is not supported if the source database has no corresponding data. |
| Forward switchover | Forward switchover is the abstraction and standardization of the conventional system cutover process, a type of switchover that does not operate business application connections, and a task flow that needs to be executed before and after the data migration link of OMS is used for application switchover. You need to make sure that the entire forward switchover process is completed before the application connections are switched over to OceanBase Database. Forward switchover will be included if you choose to perform data migration. You need to terminate forward incremental synchronization, delete the additional columns and unique indexes that the migration depends on, add the filtered CHECK constraint, and activate the triggers and foreign keys in the destination database to ensure the data integrity and availability of the destination database. If reverse incremental migration is configured, the subtasks for starting reverse incremental migration and disabling triggers and foreign keys in the source database are included in the forward switchover process to start real-time incremental synchronization from the destination database to the source database. |
| Reverse incremental migration | After the migration is completed, you can start the incremental data synchronization link on the OMS to synchronize the incremental data from the destination database to the source database (that is, in the reverse direction) before the business database switchover is completed for business cutover scenarios. Then, the changed data that occur in the destination OceanBase database after the business cutover are synchronized to the source business database in real time. You can check the performance of the reverse synchronization on OMS, including:
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