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This document describes how to use the data migration feature of DTS to migrate data from MySQL to TencentDB for MariaDB (Percona).

Data migration from MariaDB (Percona) to TencentDB for MariaDB (Percona) and from MariaDB to TencentDB for MariaDB has the same requirements as migration from MySQL to TencentDB for MariaDB (Percona). You can refer to relevant content in this document.

Notes

• During full data migration, DTS consumes certain source database resources, which may increase the load and pressure of the source database. If your database configuration is low, we recommend you migrate the data during off-peak hours.
• Full migration is implemented with tables locked, which causes write operations to be blocked for a few seconds.

Prerequisites

• You have created a TencentDB for MariaDB instance.
• The source and target databases must meet the requirements for the migration feature and version as instructed in Databases Supported by Data Migration.
• You have completed all preparations.
• You need to create a __tencentdb__ database in advance in the source MySQL database.
• You need to have the permissions of the source database.
  • To migrate the "entire instance", the following account permissions are required:

    CREATE USER 'migration account'@'%' IDENTIFIED BY 'migration password';  
    GRANT RELOAD,LOCK TABLES,REPLICATION CLIENT,REPLICATION SLAVE,SHOW DATABASES,SHOW VIEW,PROCESS ON *.* TO 'migration account'@'%';  
    GRANT INSERT, UPDATE, DELETE, DROP, SELECT, CREATE ON `__tencentdb__`.* TO 'migration account'@'%'; // If the source database is a TencentDB database, you need to grant the `__tencentdb__` permission
    GRANT SELECT ON *.* TO 'migration account';
    

  • To migrate the "specified objects", the following account permissions are required:

    CREATE USER 'migration account'@'%' IDENTIFIED BY 'migration password';  
    GRANT RELOAD,LOCK TABLES,REPLICATION CLIENT,REPLICATION SLAVE,SHOW DATABASES,SHOW VIEW,PROCESS ON *.* TO 'migration account'@'%';  
    GRANT INSERT, UPDATE, DELETE, DROP, SELECT, CREATE ON `__tencentdb__`.* TO 'migration account'@'%'; // If the source database is a TencentDB database, you need to grant the `__tencentdb__` permission
    GRANT SELECT ON `mysql`.* TO 'migration account'@'%';
    GRANT SELECT ON database to be migrated.* TO 'migration account';
    

• Permissions required of the target database: ALTER, ALTER ROUTINE, CREATE, CREATE ROUTINE, CREATE TEMPORARY TABLES, CREATE USER, CREATE VIEW, DELETE, DROP, EVENT, EXECUTE, INDEX, INSERT, LOCK TABLES, PROCESS, REFERENCES, RELOAD, SELECT, SHOW DATABASES, SHOW VIEW, TRIGGER, and UPDATE.

Application Restrictions

• Only basic tables can be migrated, while objects such as views, functions, triggers, and stored procedures cannot.
• System databases/tables and user information including information_schema, sys, performance_schema, __tencentdb__, and mysql cannot be migrated. After the migration is completed, if you want a view, stored procedure, or function in the target database to be called, you must grant the caller the read/write permissions.
• When exporting the view structure, only the definer that is the same as the target migration account's user@host can be migrated.
• Only data with the InnoDB database engine can be migrated. Tables with other engines will be skipped during migration by default.
• Correlated data objects must be migrated at the same time; otherwise, migration will fail.
• During incremental migration, if the source database has distributed transactions or generates binlog statements in the STATEMENT format, the migration will fail.

Operation Restrictions

• During migration, do not perform the following operations; otherwise, the migration task will fail:
  • Do not modify or delete user information (including username, password, and permissions) in the source and target databases and port numbers.
  • Do not run distributed transactions in the source database.
  • Do not write binlog data in the STATEMENT format into the source database.
  • Do not clear binlogs in the source database.
  • Do not delete the system table __tencentdb__ during incremental migration.
• If you only perform full data migration, do not write new data into the source database during migration; otherwise, the data in the source and target databases will be inconsistent. In scenarios with data writes, to ensure the data consistency in real time, we recommend you select full + incremental data migration.

Supported SQL Operations

Environment Requirements

Note：

The system will automatically check the following environment requirements before starting a migration task and report an error if a requirement is not met. If you can identify the failed check item, fix it as instructed in Requirements for Check Items; otherwise, wait for the system verification to complete and fix the problem according to the error message.

Directions

The data migration steps in different scenarios are basically the same. For detailed directions, see Migration from MySQL to TDSQL for MySQL.