This topic describes how to migrate full data from a self-managed TiDB database to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS).

Prerequisites

An Create an ApsaraDB RDS for MySQL instance instance is created.
Notice
  • The destination ApsaraDB RDS for MySQL instance resides in the China (Hangzhou), China (Shanghai), China (Qingdao), China (Beijing), China (Shenzhen), China (Zhangjiakou), China (Hong Kong), Singapore (Singapore), US (Silicon Valley), or US (Virginia) region.
  • The available storage space of the destination ApsaraDB RDS for MySQL instance is larger than the total size of the data in the self-managed TiDB database.

Precautions

  • DTS uses read and write resources of the source and destination databases during full data migration. This may increase the loads of the database servers. If the database performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source database, the tables have no primary keys, or a deadlock occurs in the destination database. Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. For example, you can migrate data when the CPU utilization of the source and destination databases is less than 30%.
  • The tables to be migrated in the source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
  • DTS uses the ROUND(COLUMN,PRECISION) function to retrieve values from columns of the FLOAT or DOUBLE data type. If you do not specify a precision, DTS sets the precision for the FLOAT data type to 38 digits and the precision for the DOUBLE data type to 308 digits. You must check whether the precision settings meet your business requirements.
  • DTS automatically creates a destination database in the ApsaraDB RDS for MySQL instance. However, if the name of the source database is invalid, you must manually create a database in the ApsaraDB RDS for MySQL instance before you configure the data migration task.
    Note For more information about the naming conventions of ApsaraDB RDS for MySQL databases and how to create a database, see Create a database on an ApsaraDB RDS for MySQL instance.
  • If a data migration task fails, DTS automatically resumes the task. Before you switch your workloads to the destination instance, stop or release the data migration task. Otherwise, the data in the source instance will overwrite the data in the destination instance after the task is resumed.

Billing

Migration type Task configuration fee Internet traffic fee
Schema migration and full data migration Free of charge. Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Pricing.

Migration types

Migration type Description
Schema migration DTS migrates the schemas of required objects to the destination database. DTS supports schema migration for views, tables, and databases.
Warning TiDB and MySQL are heterogeneous databases. DTS does not ensure that the schemas of the source and destination databases are consistent after schema migration. We recommend that you evaluate the impact of data type conversion on your business. For more information, see Data type mappings between heterogeneous databases.
Full data migration DTS migrates historical data of required objects to the destination database.
Note During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the size of the used tablespace of the destination database is larger than that of the source database.

Preparations

If a whitelist is configured for the TiDB database, you must add the CIDR blocks of DTS servers to the whitelist of the database. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.

Procedure

  1. Log on to the DTS console.
  2. In the left-side navigation pane, click Data Migration.
  3. At the top of the Migration Tasks page, select the region where the destination cluster resides.
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Configure the source and destination databases.
    Configure the source and destination databases
    Section Parameter Description
    N/A Task Name The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
    Source Database Instance Type The type of the source database. In this example, User-Created Database in ECS Instance is selected.
    Note If you select other instance types, you must set up the environment that is required for the self-managed database. For more information, see Preparation overview.
    Instance Region The region of the Elastic Compute Service (ECS) instance on which the source TiDB database is deployed.
    Database Type Select TiDB.
    Port Number The service port number of the source TiDB database. Default value: 4000.
    Database Account The account of the source TiDB database. The account must have the SELECT permission on the objects to be migrated and the SHOW VIEW permission.
    Database Password The password of the database account.
    Notice After you specify the information about the self-managed Oracle database, you can click Test Connectivity next to Database Password to check whether the information is valid. If the information is valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Then, modify the information based on the check results.
    Destination Database Instance Type Select RDS Instance.
    Instance Region The region where the destination instance resides.
    RDS Instance ID The ID of the destination instance.
    Database Account The database account of the destination instance. The account must have read and write permissions on the destination database. For more information about how to create and authorize a database account, see Create an account on an ApsaraDB RDS for MySQL instance and Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance.
    Database Password The password of the database account.
    Notice After you specify the information about the RDS instance, you can click Test Connectivity next to Database Password to check whether the information is valid. If the information is valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Then, modify the information based on the check results.
    Encryption Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data synchronization task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance.
    Notice The Encryption parameter is available only for regions in the Chinese mainland and the China (Hong Kong) region.
  6. In the lower-right corner of the page, click Set Whitelist and Next.
    Warning
    • If the source or destination database instance is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, or is a self-managed database hosted on Elastic Compute Service (ECS), DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database.
    • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database instance or ECS security group rules, 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: enhance the security of your account and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
    • After the DTS task is completed or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
  7. Select the migration type and the objects to be migrated.
    Select the objects to be migrated from a TiDB database
    Setting Description
    Select migration types Select both Schema Migration and Full Data Migration. For more information about migration types, see Migration types.
    Notice To ensure data consistency, do not execute DDL statements on the source TiDB database during full data migration.
    Select the objects that you want to migrate

    Select one or more objects from the Available section and click the Rightwards arrow icon to add the objects to the Selected section.

    Notice
    • You can select columns, tables, or databases as the objects to migrate.
    • By default, after an object is migrated to the destination database, the name of the object remains unchanged. You can use the object name mapping feature to rename the objects that are migrated to the destination database. For more information, see Object name mapping.
    • 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.
    Specify whether to rename objects You can use the object name mapping feature to rename the objects that are migrated to the destination instance. For more information, see Object name mapping.
    Specify the retry time range for failed connections to the source and destination databases By default, if DTS fails to connect to the source and destination databases, DTS retries within the following 12 hours. You can specify the retry time range based on your business requirements. If DTS is reconnected to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note Within the time range in which DTS attempts to reconnect to the source and destination databases, 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 the earliest opportunity after the source and destination databases are released.
  8. In the lower-right corner of the page, click Precheck.
    Note
    • Before you can start the data migration task, a precheck is performed. You can start the data migration task only after the task passes the precheck.
    • If the task fails to pass the precheck, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  9. After the task passes the precheck, click Next.
  10. In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the data migration task.
    Warning We recommend that you do not manually stop the task during full data migration. Otherwise, the data migrated to the destination database may be incomplete. You can wait until the full data migration task automatically stops.
    Full data migration

What to do next

After full data migration is complete, you can perform incremental data migration. For more information, see Migrate incremental data from a self-managed TiDB database to an ApsaraDB RDS for MySQL instance.