Oracle to OceanBase MySQL Data Replication

NineData supports schema, full, and incremental replication from Oracle to OceanBase MySQL.

Overview

NineData data replication supports schema, full data, and incremental data replication between data sources. For supported data sources, it also supports bidirectional replication for geo-distributed active-active architectures.

• Schema replication: Replicates object structures between homogeneous and heterogeneous data sources.
• Full data replication: Uses data sharding and row-level concurrent batch replication to improve throughput. Breakpoint resume helps preserve data accuracy, including for tables without primary keys.
• Incremental data replication: Replicates DML and DDL changes for supported object types. Row-level concurrency and hotspot merge processing help maintain replication throughput.
• Bidirectional real-time data replication (only between MySQL instances): Replicates changes in both directions between nodes so data can stay current across participating nodes.

Use these capabilities for full or incremental data replication, migration, synchronization, data integration, and low-downtime migration workflows.

Before you begin

• Add the Oracle source and OceanBase MySQL target to NineData. See Create an OceanBase MySQL Data Source. Data Replication supports OceanBase MySQL V4.0.

• The Oracle source must be 23ai, 21c, 19c, 18c, 12c, or 11g.

• Grant the following permissions to the source and target accounts:

  Replication type	Oracle source	OceanBase MySQL target
  Schema Replication	select connect select any dictionary select any table select_catalog_role	ALL Privileges on the database
  Full Replication	select connect select any dictionary select any table select_catalog_role	ALL Privileges on the database
  Incremental Replication	See Appendix 2: Oracle incremental replication account permissions.	ALL Privileges on the database

• For incremental replication, configure the Oracle source as follows:

  • Set the log mode to ARCHIVELOG. Run SELECT log_mode FROM v$database; to check the current mode.
  • Enable supplemental logging. Run SELECT supplemental_log_data_all allc FROM v$database; to check the setting. When needed, run ALTER DATABASE ADD SUPPLEMENTAL LOG DATA (ALL) COLUMNS;.

Restrictions

• Full initialization consumes read and write resources on both data sources. Run it during off-peak hours when possible.
• Each replicated table should have a primary key or unique constraint, and column names must be unique.
• Data type, object-name, and constraint compatibility at the target is determined by the precheck. Resolve incompatible objects before starting the task.

Procedure

1. Sign in to the NineData Console.

2. In the left navigation pane, click Replication > Data Replication.

3. On the Replication page, click Create Replication.

4. On the Source & Target tab, configure the fields in the table, and click Next.

   Parameter	Description
   Name	Enter a name for the data synchronization task. To make the task easier to find and manage later, use a meaningful name. Up to 64 characters are supported.
   Source	The data source that contains the objects to synchronize.
   Target	The data source that receives the synchronized objects.
   Target DB	Select the target database to which data is synchronized.
   Type	Select the replication type. Schema: Synchronize only the database and table schemas of the source data source, without synchronizing data. Full: Synchronize all objects and data from the source data source, namely full data replication. Incremental: After full synchronization completes, perform incremental synchronization based on the logs of the source data source.
   Incremental Started	Required only when Type is Incremental. From Started: Use the current replication task start time as the baseline for incremental replication. Customized Time: Select the point in time from which incremental replication starts. Select a time zone based on the region of your business. If the configured time point is earlier than the current replication task start time and DDL operations occurred during that period, the replication task will fail.
   Spec (Unavailable only when Schema is selected)	The specification of the replication task. A larger specification provides a higher replication rate. Hover over the icon to view the rate and configuration information of each specification. Each specification shows the available quantity and total quantity. When the available quantity is 0, the specification is grayed out and cannot be selected.
   If target table already exists (Required when Schema is selected)	Pre-Check Error and Stop Task: Stop the task when a table with the same name is detected during the precheck stage. Skip and Continue Task: When a table with the same name is detected during the precheck stage, display a message and continue the task. During schema replication, ignore the table with the same name. If you also perform data replication, data is appended to the table with the same name and existing data is not overwritten. Delete Objects and Rewrite: When a table with the same name is detected during the precheck stage, display a message and continue the task. During schema replication, delete the table with the same name in the target database and replicate the table schema again based on the source database. If you also perform data replication, data is written after schema replication completes.
   Target Table Exists Data (Required when Full is selected)	Pre-Check Error and Stop Task: Stop the task when data is detected in the target table during the precheck stage. Ignore existing target data and append to it.: When data is detected in the target table during the precheck stage, ignore that data and append other data. Clear target existing data before write: When data is detected in the target table during the precheck stage, delete that data and write it again.
   Incremental data conflict handling strategy for target table (Required when Incremental is selected)	Runtime error: During incremental replication, report an error when target data already exists and wait for manual intervention. Do not update target data: During incremental replication, do not write data when target data already exists, and continue subsequent tasks. Update target data: During incremental replication, overwrite the target data when target data already exists.

5. On the Objects tab, configure the parameters in the table, and click Next.

   Parameter	Description

   To create multiple replication tasks with the same replication objects, import a configuration file. Click Import Config, click Download Template to download the template, edit the file, and then click Upload to upload it and import the objects in bulk. The configuration file uses these fields:

7. On the Pre-check tab, wait for NineData to complete the precheck. After the precheck passes, click Launch.

   • Select Enable data consistency comparison to start a data consistency comparison task based on the source data source after synchronization completes. Based on the selected Type, Enable data consistency comparison starts at these times:

     • Schema: Starts after schema replication completes.
     • Schema+Full: Starts after full replication completes.
     • Full: Starts after full replication completes.
     • Schema+Full+Incremental, Incremental: Starts when incremental data is consistent with the source data source for the first time and Delay is 0 seconds. Click View Details to view synchronization delay on the Details page.

   • If the precheck fails, click Details in the Actions column for the failed check item, review the cause, fix the issue, and then click Check Again to run the precheck again until it passes.

   • Items with Warning in Result can be fixed or ignored if required.

8. On the Launch page, the Launch Successfully message appears, indicating that the synchronization task has started. Then perform these actions:

   • Click View Details to view the execution status of each stage of the synchronization task.
   • Click Back to list to return to the Replication task list page.

Result

1. Sign in to the NineData Console.

2. In the navigation menu, select Replication > Data Replication.

3. On the Replication page, click the Task ID of the target synchronization task. The task details page shows the following information.

   

   Number	Function	Description
   1	Sync Delay	The synchronization delay between the source and target data sources. 0 seconds means the target has caught up with the source. Switch traffic based on your migration plan.
   2	Configure Alerts	When the task fails, NineData notifies the selected channel through the configured alert.
   3	More	Pause: Pause the task. Only tasks with Running status are selectable. Duplicate: Create a new replication task with the same configuration as the current task. Terminate: Terminate tasks that are incomplete or still listening (that is, in incremental synchronization). After a task is terminated, it cannot be restarted, so proceed with caution. If the synchronization objects contain triggers, trigger replication options appear for selection. Delete: Delete the task. Once deleted, it cannot be recovered, so proceed with caution.
   4	Structure Replication (displayed in scenarios involving structure replication)	Displays the progress and detailed information of structure replication. Select Log to view the execution logs of structure replication. Select the to view the latest information. Select View DDL in the Actions column for the target object in the list to view SQL replay.
   5	Full Replication (displayed in scenarios involving full replication)	Displays the progress and detailed information of full replication. Select Monitor to view various monitoring indicators during full replication. During full replication, select Flow Control Settings on the monitoring page to limit the rate of writing to the target data source per second. The unit is rows/second. Select Log to view the execution logs of full replication. Select the to view the latest information.
   6	Incremental Replication (displayed in scenarios involving incremental replication)	Displays incremental replication indicators. Select View Threads to view the operations currently being executed by the current replication task, including: Thread ID: Replication tasks are executed in multiple threads, and this shows the current thread number. Execute SQL: Details of the SQL statement currently being executed by the current thread. Response Time: The response time of the current thread. If this value increases, it indicates that the current thread may be stuck for some reason. Event Time: The timestamp when the current thread was started. Status: The status of the current thread. Select Flow Control Settings to limit the rate of writing to the target data source per second. The unit is rows/second. Select Log to view the execution logs of incremental replication. Select the to view the latest information.
   7	Modify Object	Displays the modification records of synchronization objects. Select Modify Objects to configure the synchronization objects. Select the to view the latest information.
   8	Data Comparison	Displays the comparison results between the source and target data sources. If data comparison is not enabled, select Enable Comparison on the page to enable it. Select Re-compare to rerun the comparison for the current source and target data sources. Select Stop to stop the comparison task immediately after it starts. Select Log to view the execution logs of consistency comparison. Select Monitor (displayed only in data comparison) to view the trend chart of RPS (records per second) comparison. Select Details to view earlier records. Select the in the Actions column in the comparison list (displayed under the Data tab only when inconsistencies are found) to view details of the comparison between the source and target data sources. Select the in the Actions column in the comparison list (displayed only when inconsistencies are found): Generate change SQL. Copy this SQL to the target data source and run it to fix the mismatch.
   9	Expand	Displays detailed information of the current replication task. Common actions: Export table configuration: Export the current task's database and table configuration for quick import when creating another replication task with the same objects. Alert Rules: Configure alerts for the current task.

Appendix 1: Precheck items

Check item	What NineData checks
Source data source connection check	Oracle gateway status, instance accessibility, and account information.
Target data source connection check	OceanBase MySQL gateway status, instance accessibility, and account information.
Source database permission check	Whether the Oracle source account has the required permissions.
Target database permission check	Whether the OceanBase MySQL target account has the required permissions.
Target database data existence check	Whether replicated objects already contain data at the target.
Target database same-name object existence check	Whether replicated objects already exist at the target.
Source database log archiving mode check	Whether the Oracle source uses ARCHIVELOG.
Source database supplemental logging check	Whether Oracle supplemental logging is enabled and set to ALL.
Source database table key check	Whether replicated objects lack a primary key or unique key.

Appendix 2: Oracle incremental replication account permissions

Below Oracle 12c

Designate a user with DBA privileges for incremental data replication tasks with Oracle as the source.

-- Create NineData sync account
CREATE USER test_dba IDENTIFIED BY "ninedatasync";
-- Grant DBA privileges to the account
GRANT dba to test_dba;

Oracle 12c and above

Designate a user with DBA privileges for incremental data replication tasks with Oracle as the source.

-- Create NineData sync account in the global environment
CREATE USER c##test_dba IDENTIFIED BY "ninedatasync";
-- Grant DBA and connect privileges to the account, specifying the scope of the privileges
GRANT dba, connect to c##nine_data container=all;

Next steps

• Create an OceanBase MySQL Data Source
• Data Replication overview