Custom DML/DDL configurations

This topic introduces how to customize DDL and DML configuration in incremental synchronization when configuring data migration tasks.

Background information

When configuring a data migration task, if you select Incremental Synchronization in the Select Migration Type and Objects step, DML synchronization is supported by default. You can customize the configuration of DML or DDL.

• DML Synchronization: When configuring a data migration task, you can set synchronization strategies for DML SQL statements that need to be synchronized. Only SQL statements that meet the set conditions will be synchronized to the target. This feature is commonly used in historical table and transaction detail table scenarios.

• DDL Synchronization: When configuring a data migration task, you can set whether to synchronize DDL. Only after setting DDL synchronization will DDL statements such as CREATE, ALTER, DROP, or TRUNCATE TABLE be synchronized to the target. This feature is commonly used for long-term data migration tasks and can significantly reduce the cost of task maintenance.

Limitations

• DML Synchronization

  • The scope of DML filtering applies to the entire data migration task.

  • Full data verification is not supported for data migration tasks with DML filtering selected.

• DDL Synchronization

  • Except for supported incremental DDL types, other types are not supported.

    Note

    For the DDL statement CREATE TABLE, Migrations only supports creating a table with the same name after DROP TABLE using CREATE TABLE. Currently, it does not support using CREATE TABLE to create new tables.

  • If the tables to be synchronized involve unsupported DDL types, the data migration task may be interrupted and cause data issues, which cannot be recovered.

  • Do not perform DDL operations that change the schema of databases or tables during schema migration and full migration, as this may cause the data migration task to be interrupted.

Procedure

1. Configure the data migration task to the Select Type & Objects step.

   For more information, see the documentation on creating data migration tasks in the Data migration module for the respective types.

   

2. On the Select Type & Objects page, check Incremental Synchronization, and DML synchronization is checked by default.

   

3. Customize DML/DDL synchronization configuration.

   • Customize DML synchronization configuration

     Click the Edit icon in the Incremental Synchronization > DML Synchronization area. In the DML Synchronization Configuration dialog box, select the DML to be synchronized and click Save.

     DML synchronization supports INSERT, DELETE, and UPDATE. You can filter as needed.

     

   • Customize DDL synchronization configuration

     After checking DDL Synchronization, click the displayed Edit icon. In the DDL Synchronization Configuration dialog box, select the DDL to be synchronized and click Save.

     For the range of DDL synchronization supported by different types of data migration tasks, see DDL synchronization range. You can customize the DDL configuration based on the supported DDL synchronization range.

     

4. Configure the subsequent task according to the prompts.