This topic describes how to migrate data from a user-created TiDB database to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS).
- The destination ApsaraDB RDS for MySQL instance reside in the China (Hangzhou), China (Shanghai), China (Qingdao), China (Beijing), China (Shenzhen), China (Zhangjiakou-Beijing Winter Olympics), China (Hong Kong), Singapore, US (Silicon Valley), US (Virginia). The feature is available only in these regions.
- The available storage space of the destination ApsaraDB RDS for MySQL instance is larger than the total size of the data in the user-created TiDB database.
- DTS uses read and write resources of the source and destination databases during full data migration. This may increase the database load. 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 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 usage of the source and destination databases is less than 30%.
- The source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, duplicate data may exist in the destination database.
- DTS uses the
ROUND(COLUMN,PRECISION)function to retrieve values from columns of the float or double data type. If the precision is not specified, 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
Note For more information about how to create a database and the database naming conventions, see Create databases and accounts.
- DTS automatically resumes a failed data migration task. Before you switch your workloads to the destination database, stop or release the data migration task. Otherwise, the data in the source database will overwrite the data in the destination database after the task is resumed.
|Migration type||Instance configuration||Internet traffic|
|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.|
|Schema migration||DTS migrates the schemas of the required objects to the destination database. DTS
supports schema migration for the following types of objects: database, table, and
Warning Heterogeneous databases support different data types. DTS maps a data type in the source database to a data type supported by the destination database during schema migration. 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.
Notice 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.
Permissions required for database accounts
|Database||Schema migration||Full data migration|
|TiDB database||The SELECT permission||The SHOW VIEW permission and the SELECT permission on the required objects.|
|ApsaraDB RDS for MySQL instance||The read/write permissions||The read/write permissions|
For more information about how to create and authorize a database account in the ApsaraDB RDS for MySQL instance, see Create an account for an ApsaraDB RDS for MySQL instance and Modify the permissions of an account for an RDS instance.
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.
- Log on to the DTS console.
- In the left-side navigation pane, click Data Migration.
- At the top of Migration Tasks the page, select the region where the destination cluster resides.
- In the upper-right corner of the page, click Create Migration Task.
- Configure the source and destination databases for the data migration task.
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 where the source database is deployed. The procedure in this topic uses a user-created database hosted on ECS as an example.Note If you select other instance types, you must prepare the environments that are 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. For more information about the permissions that are required for the account, see Permissions required for database accounts. 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. For more information about the permissions that are required for the account, see Permissions required for database accounts. 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 for an RDS MySQL instance.Notice The Encryption parameter is available only for regions in mainland China and the Hong Kong (China) region.
- 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.
- Select the migration types and objects to be migrated.
Parameter Description 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 data migration. Objects
Select objects from the Available section and click the 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 change the names of the objects that are migrated to the destination database by using the object name mapping feature. For more information about how to use this feature, 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.
- Click Precheck on the lower right of the page.
- A precheck is performed for a data migration task. A data migration task can be started only if it passes the precheck.
- If the precheck fails, click icon corresponding to each failed item to view the details. Fix the problems as instructed and run the precheck again.
- After the precheck is passed, click Next.
- On the Confirm Settings dialog box that appears, specify Channel Specification and select the Data Transmission Service (Pay-As-You-Go) Service Terms.
- Click Buy and Start to start the migration task.
Warning We recommend that you do not manually stop a data migration task. Otherwise, data migrated to the destination database will be incomplete. Wait until the migration task automatically stops.