This topic describes how to migrate data from a user-created MySQL database to MyBase for MySQL by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. When you migrate data from a user-created MySQL database to Alibaba Cloud, you can use all of the supported migration types to ensure service continuity.

Prerequisites

  • A MyBase for MySQL instance is created. For more information, see Create an instance in an ApsaraDB for MyBase dedicated cluster.
  • The version of the user-created MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.
  • The available storage space of the instance is larger than the total size of the data in the user-created MySQL database.

Notes

  • DTS consumes read and write resources of the source and destination databases during full data migration. This may increase the database loads. Database services may become unavailable in the following scenarios: the database performance is unfavorable, the server specifications cannot meet your requirements, and the data volume is large. For example, database services become unavailable when a large number of slow SQL queries are performed on the source database, tables in the source database 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 utilization rates of both the source and destination databases are 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 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 database in the MyBase for MySQL instance. However, if the name of the source database is not valid, you must create a database in the MyBase for MySQL instance before you configure the migration task.
    Note For information about how to create a database and the database naming conventions, see Create a database.
  • If a data migration task fails, DTS automatically resumes the 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.

Billing

Migration type Instance configurations 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.
Incremental data migration Charged. For more information, see Pricing.

Migration types

  • Schema migration

    DTS migrates the schemas of objects to the destination instance. DTS supports schema migration for tables, views, triggers, stored procedures, and functions.

    Note
    • During schema migration, DTS changes the value of the SECURITY attribute from DEFINER to INVOKER for views, stored procedures, and functions.
    • DTS does not migrate user information. Before a user can call views, stored procedures, and functions of the destination database, you must grant the read and write permissions to the user.
  • Full data migration
    DTS migrates all the data of the objects to be migrated from the user-created MySQL database to the database in the MyBase for MySQL instance.
    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.
  • Incremental data migration

    After full data migration is complete, DTS reads binary log files of the user-created MySQL database and synchronizes incremental data from the user-created MySQL database to the MyBase for MySQL instance. Incremental data migration allows you to ensure service continuity when you migrate data from a user-created MySQL database to Alibaba Cloud.

SQL operations that can be synchronized during incremental data migration

Operation SQL statement
DML INSERT, UPDATE, DELETE, and REPLACE
DDL
  • ALTER TABLE and ALTER VIEW
  • CREATE FUNCTION, CREATE INDEX, CREATE PROCEDURE, CREATE TABLE, and CREATE VIEW
  • DROP INDEX and DROP TABLE
  • RENAME TABLE
  • TRUNCATE TABLE

Database account permissions required for migration

Database Schema migration Full data migration Incremental data migration
User-created MySQL database The SELECT permission The SELECT permission The REPLICATION SLAVE, REPLICATION CLIENT, SHOW VIEW, and SELECT permissions
MyBase for MySQL instance The read and write permissions The read and write permissions The read and write permissions

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

Preparations

Create an account for a user-created MySQL database and configure binary logging

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 RDS instance resides.Select a region
  4. In the upper-right corner of the page, click Create Migration Task.
  5. Configure the source and destination databases for the data migration task. Configure the source and destination databases for the data migration task
    Section Parameter Description
    No 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 information Instance Type Select an instance type based on where the source database is deployed. In this example, select User-Created Database with Public IP Address.
    Note If you select another instance type, you must prepare the environment that is required for the source database. For more information, see Preparation overview.
    Instance Region If the instance type is set to User-Created Database with Public IP Address, you do not need to specify the instance region.
    Note If a whitelist is configured for the user-created MySQL database, you must manually add the CIDR blocks of DTS servers to the whitelist of the user-created MySQL database. You can click Get IP Address Segment of DTS next to Instance Region to obtain the CIDR blocks of DTS servers.
    Database Type Select MySQL.
    Hostname or IP Address Enter the endpoint that is used to connect to the user-created MySQL database. In this example, enter the public IP address.
    Port Enter the service port number of the user-created MySQL database. The default port number is 3306.
    Database Account Enter the account of the user-created MySQL database. For more information about the permissions that are required for the account, see Database account permissions required for migration.
    Database Password Enter the password for the source database account.
    Note 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 information Instance Type Select RDS Instance.
    Instance Region Select the region where the destination instance resides.
    RDS Instance ID Select the ID of the destination instance.
    Database Account Enter the database account of the destination instance. For more information about the permissions that are required for the account, see Database account permissions required for migration.
    Database Password Enter the password for the destination database account.
    Note 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 Specifies whether to enable encryption on the destination instance. 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.
    Note 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.
    Note The IP addresses of DTS servers are automatically added to a whitelist of the destination instance. This ensures that the DTS servers can connect to the destination instance.
  7. Select the migration types and the objects to be migrated. Select the migration types and the objects to be migrated
    Parameter Description
    Migration Types
    • To perform only full data migration, select Schema Migration and Full Data Migration.
    • To migrate data with minimal downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration.
    Note If Incremental Data Migration is not selected, do not write data to the source database during full data migration. This ensures data consistency between the source and destination databases.
    Objects

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

    Note
    • The selected objects can be databases, tables, or columns.
    • By default, the name of an object remains unchanged after migration. 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.
    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, click the Info icon icon next to each failed item to view details. Troubleshoot the issues based on the causes and run the precheck again.
  9. After the task passes the precheck, click Next.
  10. In the Confirm Settings dialog box, specify the Channel Specification and select the Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the migration task.

Stop the migration task

Warning We recommend that you prepare a rollback solution to migrate incremental data from the destination database to the source database in real time. This allows you to minimize the negative impact of switching your workloads to the destination database. For more information, see Switch workloads to the destination database. If you do not need to switch your workloads, perform the following steps to complete the migration task.
  • Full data migration

    Do not manually stop a task during full data migration. Otherwise, the system may fail to migrate all data. Wait until the migration task automatically ends.

  • Incremental data migration

    The task does not automatically end during incremental data migration. You must manually stop the migration task.

    1. Wait until the task progress bar shows Incremental Data Migration and The migration task is not delayed. Then, stop writing data to the source database for a few minutes. In some cases, the progress bar shows the delay time of incremental data migration.
    2. After the status of incremental data migration changes to The migration task is not delayed, manually stop the migration task.Stop a task during incremental migration

What to do next

The database accounts used for data migration have the read and write permissions. After you complete the data migration, delete the database accounts to ensure security.