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

Prerequisites

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

Precautions

  • DTS uses read and write resources of the source and destination databases during full data migration. This may increase the load of the database server. 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 how to create a database and the database naming conventions, 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 database will overwrite the data in the destination instance after the task is resumed.

Billing

Migration type Instance 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 the 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 the 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 tablespace of the destination database is larger than that of the source database.

Before you begin

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.
    Select a region
  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 DTS automatically generates a task name. We recommend that you specify an informative name for easy identification. You do not need to use a unique task name.
    Source Database Instance Type Select an instance type based on the deployment of the source database. In this example, select User-Created Database in ECS Instance.
    Note If you select other instance types, you must prepare the environment that is required for the source database. For more information, see Preparation overview.
    Instance Region Select the region of the ECS instance on which the source TiDB database is deployed.
    Database Type Select TiDB.
    Port Number Enter the service port number of the source TiDB database. The default port number is 4000.
    Database Account Enter 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 Enter the password of the source database account.
    Notice After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the source database parameters based on the check results.
    Destination Database Instance Type Select RDS Instance.
    Instance Region Select the region where the destination RDS instance resides.
    RDS Instance ID Select the ID of the destination RDS instance.
    Database Account Enter the database account of the destination RDS instance. The account must have the 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 Enter the password of the destination database account.
    Notice After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the parameters are valid. If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the destination database parameters 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 RDS instance before you configure the data migration task. For more information, see Configure SSL encryption on an ApsaraDB RDS for MySQL instance.
    Notice The Encryption parameter is available only for regions in mainland China and the China (Hong Kong) region.
  6. In the lower-right corner of the page, click Set Whitelist and Next.
    DTS adds the CIDR blocks of DTS servers to the whitelist of the destination ApsaraDB RDS for MySQL instance. This ensures that DTS servers can connect to the destination RDS instance.
  7. Select the migration types and the objects to be migrated.
    Select the objects to be migrated from a TiDB database
    Setting Description
    Select the 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 write data to the source TiDB database during full data migration.
    Select the objects to be migrated

    Select objects from the Available section and click the Right arrow icon to move the objects to the Selected section.

    Notice
    • You can select columns, tables, or databases as the objects to be migrated.
    • 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 change the names of the objects that are migrated to the destination database. For more information, see Object name mapping.
    • If you use the object name mapping feature on an object, other objects that are dependent on the object may fail to be migrated.
  8. In the lower-right corner of the page, click Precheck.
    Notice
    • Before you can start the data migration task, a precheck is performed. A data migration task can be started only if it passes the precheck.
    • If the task fails to pass the precheck, click the Info icon icon next to each failed item to view details. Troubleshoot the issues based on the causes and perform 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 migration task.
    Warning Do not manually stop a task during full data migration. Otherwise, data migrated to the destination database will be incomplete. Wait until the migration task automatically stops.
    Full data migration