Parameter | Description |
Migration Types | To perform only full data migration, select Schema Migration and Full Data Migration. To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.
Note If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases. |
Processing Mode of Conflicting Tables | Precheck and Report Errors: checks whether the destination database contains tables that use the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started. Note If the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. For more information, see Map object names. Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases. Warning If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to the following potential risks: If the source and destination databases have the same schema, and a data record has the same primary key as an existing data record in the destination database, the following scenarios may occur: During full data migration, DTS does not migrate the data record to the destination database. The existing data record in the destination database is retained. During incremental data migration, DTS migrates the data record to the destination database. The existing data record in the destination database is overwritten.
If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
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SQL Server Incremental Synchronization Mode | Log-based Parsing for Non-heap Tables and CDC-based Incremental Synchronization for Heap Tables (Hybrid Log-based Parsing): Advantages: This mode supports heap tables, tables without primary keys, compressed tables, and tables with computed columns. This mode provides higher stability and a variety of complete DDL statements.
Disadvantages: DTS creates the trigger dts_cdc_sync_ddl, the heartbeat table dts_sync_progress, and the DDL storage table dts_cdc_ddl_history in the source database and enables change data capture (CDC) for the source database and specific tables. You cannot execute the SELECT INTO or TRUNCATE statement on tables with CDC enabled in the source database. Triggers created by DTS in the source database cannot be manually deleted.
Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported): Advantages: This mode does not modify the settings of the source database. Disadvantages: This mode does not support heap tables, tables without primary keys, compressed tables, or tables with computed columns.
Select Polling and querying CDC instances for incremental synchronization. Advantages: Full or incremental migration is supported when the source database is Amazon RDS SQL Server, Azure SQL Database, or Google Cloud SQL for SQL Server. If you use the native CDC component of SQL Server to obtain incremental data, incremental migration is more stable and occupies less network bandwidth.
Disadvantages: The source database account that is used by the DTS instance must have the permission to enable CDC. Incremental data migration takes about 10 seconds. If you configure a task to migrate multiple tables in multiple databases, stability and performance issues may occur.
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DDL and DML Operations to Be Synchronized | The SQL operations to be migrated at the instance level. For more information, see the SQL operations that can be incrementally migrated section of this topic. Note To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to incrementally migrate. |
Source Objects | Select one or more objects from the Source Objects section. Click the icon to add the objects to the Selected Objects section. Note In this scenario, data migration is performed between heterogeneous databases. Therefore, only tables can be migrated. Other objects such as views, triggers, or stored procedures are not migrated to the destination database. |
Selected Objects | - To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
- To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
Note - If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
- To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information about how to specify the conditions, see Specify filter conditions.
- To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate. For more information, see the SQL operations that can be incrementally migrated section of this topic.
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