Data Transmission Service：Migrate data from an ApsaraDB RDS for SQL Server instance to an AnalyticDB for MySQL V3.0 cluster

Supported source databases

You can use DTS to migrate data from the following types of SQL Server databases to an AnalyticDB for MySQL V3.0 cluster. In this topic, an ApsaraDB RDS for SQL Server instance is used to describe how to configure a data migration task. You can also follow the procedure to configure data migration tasks for other types of SQL Server databases.

• ApsaraDB RDS for SQL Server instance

• Self-managed databases:

  • Self-managed database with a public IP address
  • Self-managed database that is hosted on Elastic Compute Service (ECS)
  • Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway
  • Self-managed database that is connected over Database Gateway

Prerequisites

• The new DTS console is used. You can configure a data migration task for this scenario only in the new DTS console.

• The source ApsaraDB RDS for SQL Server instance is created. For more information, see Overview of data migration scenarios and Create an ApsaraDB RDS for SQL Server instance.

  Important

  If the database version of the ApsaraDB RDS for SQL Server instance is 2008 or 2008 R2, incremental data migration is not supported.

• The destination AnalyticDB for MySQL V3.0 cluster is created. For more information, see Create a cluster.

• The available storage space of the destination AnalyticDB for MySQL V3.0 cluster is larger than the total size of the data in the source ApsaraDB RDS for SQL Server instance.

• If the source ApsaraDB RDS for SQL Server instance meets one of the following conditions, we recommend that you split the migration task into multiple subtasks:

  • The source instance contains more than 10 databases.

  • A single database of the source instance backs up its logs at an interval of less than 1 hour.

  • A single database of the source instance executes more than 100 DDL statements each hour.

  • Logs are written at a rate of 20 MB/s for a single database of the source instance.

  • The change data capture (CDC) feature needs to be enabled for more than 1,000 tables in the source ApsaraDB RDS for SQL Server instance.

Limits

Billing

Migration types

• Schema migration

  DTS migrates the schemas of the selected objects from the source database to the destination database.

  • DTS supports schema migration for the following types of objects: schema, table, view, function, and procedure.

  • DTS does not migrate the schemas of assemblies, service brokers, full-text indexes, full-text catalogs, distributed schemas, distributed functions, Common Language Runtime (CLR) stored procedures, CLR scalar-valued functions, CLR table-valued functions, internal tables, systems, or aggregate functions.

  Warning

  ApsaraDB RDS for SQL Server and AnalyticDB for MySQL are heterogeneous databases. The data types that they support do not have one-to-one correspondence. In this case, the task may fail or data loss may occur. We recommend that you evaluate the impact of data type mappings on your business. For more information, see Data type mappings between heterogeneous databases.

• Full data migration

  DTS migrates the historical data of required objects from the source database to the destination database.

• Incremental data migration

  After full data migration is completed, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.

SQL operations that can be incrementally migrated

Permissions required for database accounts

For more information about how to create a database account and grant permissions to the database account, see the following topics:

• ApsaraDB RDS for SQL Server instance: Create a privileged account or a standard account and Modify the permissions of an account

• AnalyticDB for MySQL V3.0 cluster: Create a database account

Procedure

1. Go to the Data Migration Tasks page.

   1. Log on to the Data Management (DMS) console.

   2. In the top navigation bar, move the pointer over DTS.

   3. Choose DTS (DTS) > Data Migration.

   Note

   • The actual operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.

   • You can also go to the Data Migration page of the new DTS console.

2. From the drop-down list on the right side of Data Migration Tasks, select the region in which your data migration instance resides.

   Note

   If you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.

3. Click Create Task. In the Create Task wizard, configure the source and destination databases. The following table describes the parameters.

   Warning

   After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

   Section	Parameter	Description
   N/A	Task Name	The name of the task. DTS automatically generates a task name. We recommend that you specify an informative name to identify the task. You do not need to specify a unique task name.
   Source Database	Database Type	The type of the source database. Select SQL Server.
   	Access Method	The access method of the source database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the source ApsaraDB RDS for SQL Server instance resides.
   	Instance ID	The ID of the source ApsaraDB RDS for SQL Server instance.
   	Database Account	The database account of the source ApsaraDB RDS for SQL Server instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password that is used to access the database instance.
   Destination Database	Database Type	The type of the destination database. Select AnalyticDB for MySQL 3.0.
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination AnalyticDB for MySQL V3.0 cluster resides.
   	Instance ID	The ID of the destination AnalyticDB for MySQL V3.0 cluster.
   	Database Account	The database account of the destination AnalyticDB for MySQL V3.0 cluster. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password that is used to access the database instance.

4. In the lower part of the page, click Test Connectivity and Proceed.

   If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the IP address whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must make sure that the ECS instance can access the database. If the self-managed database is hosted on multiple ECS instances, you must manually add the CIDR blocks of DTS servers to the security group rules of each ECS instance. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the IP address whitelist of the database to allow DTS to access the database. For more information, see the CIDR blocks of DTS servers section of the Add the CIDR blocks of DTS servers topic.

   Warning

   If the public CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database instance or to the security group rules of an ECS instance, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or security group rules and forbidding unauthorized CIDR blocks, or connecting the database instance to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

5. Configure the objects to be migrated and advanced settings.

   Parameter	Description
   Migration Types	To perform only full data migration, select Schema Migration and Full Data Migration. To migrate data without service downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If Full Data Migration is selected, you can migrate the schema and data of the table that is created by using the CREATE TABLE statement to the destination database. If Incremental Data Migration is not selected, 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.
   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.
   DDL and DML Operations to Be Synchronized	The SQL operations to be migrated during incremental data migration 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 the Map the name of a single object section of the Map object names topic. To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see the Map multiple object names at a time section of the Map object names topic. Note If you use the object name mapping feature to rename an object, other objects that depend on the object may fail to be migrated. 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.

6. Click Next: Advanced Settings to configure advanced settings.

   Parameter	Description
   Monitoring and Alerting	Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see Configure monitoring and alerting when you create a DTS task.
   Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you set different retry time ranges for multiple data migration tasks that have the same source or destination database, the shortest retry time range that is set takes precedence. When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
   Retry Time for Other Issues	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the change tracking task fails. Important The value of the Retry Time for Other Issues parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
   Configure ETL	Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.

7. Specify the primary key columns and distribution key columns of the tables that you want to migrate to the destination AnalyticDB for MySQL cluster.

   Note

   • If you select Schema Migration for the Migration Types parameter, you must configure the Type, Primary Key Column, and Distribution Key parameters for the tables that you want to migrate to the AnalyticDB for MySQL V3.0 cluster. For more information, see CREATE TABLE.

   • In the Primary Key Column field, you can select multiple columns to form a composite primary key. In this case, you must select one or more primary key columns as distribution keys.

8. In the lower part of the page, click Next: Save Task Settings and Precheck.

   You can move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters to view the parameters to be specified when you call the relevant API operation to configure the DTS task.

   Note

   • Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.

   • If the task fails to pass the precheck, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.

   • If an alert is triggered for an item during the precheck:

     • If an alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.

     • If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur, and your business may be exposed to potential risks.

9. Wait until Success Rate becomes 100%. Then, click Next: Purchase Instance.

10. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

    Section	Parameter	Description
    New Instance Class	Resource Group Settings	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
    	Instance Class	DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Specifications of data migration instances.

11. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

12. Click Buy and Start. In the dialog box that appears, click OK.

    You can view the progress of the task in the task list.