This topic describes how to migrate data from an ApsaraDB RDS for MariaDB TX instance to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. When you migrate data from an ApsaraDB RDS for MariaDB TX instance to an ApsaraDB RDS for MySQL instance, you can select all of the supported migration types to ensure service continuity.

Prerequisites

An ApsaraDB RDS for MySQL instance is created. For more information, see Create an ApsaraDB RDS for MySQL instance.
Note The available storage space of the ApsaraDB RDS for MySQL instance must be larger than the total size of the data in the ApsaraDB RDS for MariaDB TX instance.

Precautions

  • 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 automatically resumes a failed data migration 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 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 the required objects to the destination instance. DTS supports schema migration for the following types of object: table, view, trigger, stored procedure, and function. DTS does not support schema migration for events.

    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 instance, you must grant the read/write permissions to the user.
  • Full data migration
    DTS migrates historical data of the required objects to the destination instance.
    Note
    • During full data migration, concurrent INSERT operations cause segments in the tables of the destination instance. After full data migration is completed, the tablespace of the destination instance is larger than that of the source instance.
    • To ensure successful data migration, do not perform DDL operations on the source instance during full data migration.
  • Incremental data migration

    After full migration is completed, DTS retrieves binary log files from the source instance, and migrates incremental data to the destination instance in real time.

SQL operations that can be synchronized during incremental data migration

Operation type SQL statements
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

Permissions required for database accounts

Database Schema migration Full data migration Incremental data migration
Source ApsaraDB RDS for MariaDB TX instance The SELECT permission The SELECT permission The REPLICATION SLAVE permission, the REPLICATION CLIENT permission, the SHOW VIEW permission, and the permission to perform SELECT operations on the required objects
Destination ApsaraDB RDS for MySQL instance The read/write permissions The read/write permissions The read/write permissions

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

Procedure

  1. Log on to the DTS console.
  2. In the left-side navigation pane, click Data Migration.
  3. At the top of Migration Tasks the 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 for the data migration task.
    Configure the source and destination databases
    Section Parameter Description
    N/A Task Name DTS automatically generates a task name. We recommend that you use an informative name for easy identification. You do not need to use a unique task name.
    Source Database Instance Type Select RDS Instance.
    Instance Region Select the region where the source ApsaraDB RDS for MariaDB TX instance resides.
    RDS Instance ID Select the ID of the source ApsaraDB RDS for MariaDB TX instance.
    Database Account Enter the database account of the source ApsaraDB RDS for MariaDB TX 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 database account.

    After you specify the source database parameters, click Test Connectivity next to the Database Password parameter to verify whether the parameters are valid.

    Note If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the parameters based on the check results.
    Destination Database Instance Type Select RDS Instance.
    Instance Region Select the region where the destination ApsaraDB RDS for MySQL instance resides.
    RDS Instance ID Select the ID of the destination ApsaraDB RDS for MySQL instance.
    Database Account Enter the database account of the destination ApsaraDB RDS for MySQL 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 database account.

    After you specify the destination database parameters, click Test Connectivity next to the Database Password parameter to verify whether the parameters are valid.

    Note If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the parameters based on the check results.
    Encryption Select Non-encrypted or SSL-encrypted. If you select SSL-encrypted, you must have enabled SSL encryption for the ApsaraDB RDS for MySQL instance. For more information, see Configure SSL encryption for an RDS MySQL instance.
    Note The Encryption parameter is available only for data migration instances that reside in mainland China and Hong Kong (China).
  6. In the lower-right corner of the page, click Set Whitelist and Next.
    Note The CIDR blocks of DTS servers are automatically added to the whitelist of the destination instance. This ensures that DTS servers can connect to the destination instance.
  7. Select the migration types and objects to be migrated.
    Select the migration types and objects to be migrated
    Item Description
    Migration types
    • To perform only full data migration, select Schema Migration and Full Data Migration.
    • If you want to migrate data without business disruptions, select Schema Migration, Full Data Migration, and Incremental Data Migration.
    Note If Incremental Data Migration is not selected, do not write data into the source database during full data migration. This ensures data consistency between the source and destination databases.
    Objects to be migrated

    Select the objects to be migrated in the Available section and click > to move them to the Selected section.

    Note
    • Objects to be migrated can be databases, tables, or columns.
    • By default, the selected objects are not renamed after the migration. If you want to rename the objects that are migrated to the destination instance, you can use the object name mapping feature provided by DTS. For more information about how to use this feature, see Object name mapping.
    • If you use the object name mapping feature for an object, objects that depend on the object may fail to be migrated.
  8. Click Precheck on the lower right of the page.
    Note
    • 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 Note corresponding to each failed item to view the details. Fix the problems as instructed and run the precheck again.
  9. After the precheck is passed, click Next.
  10. On the Confirm Settings dialog box that appears, specify Channel Specification and select the Data Transmission Service (Pay-As-You-Go) Service Terms.
  11. Click Buy and Start to start the data 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, you can stop the migration task by using the following procedure.
  • 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 that are used for data migration have the read/write permissions. After the data migration is completed, you must delete the database accounts of both the ApsaraDB RDS for MariaDB TX instance and the ApsaraDB RDS for MySQL instance to ensure database security.