This topic describes how to migrate data from a self-managed MySQL database to Migrate data from a self-managed MySQL database to an ApsaraDB MyBase 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 a self-managed MySQL database to Alibaba Cloud, you can select all of the supported migration types to ensure service continuity.

In this topic, operations are performed in the new version of the DTS console. For information about how to migrate data from a self-managed MySQL database to an ApsaraDB MyBase for MySQL instance in the old version of the DTS console, see Migrate data from a self-managed MySQL database to an ApsaraDB MyBase for MySQL instance.

Prerequisites

  • The version of the self-managed MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.
  • An ApsaraDB MyBase for MySQL instance is created. For more information, see Create an ApsaraDB MyBase for MySQL instance.
  • The available storage space of the instance is larger than the total size of the data in the self-managed MySQL database.
  • If the source MySQL database is an on-premises database, the CIDR blocks of DTS servers must be added to the IP whitelist of the database. This ensures that DTS servers can access the source MySQL database. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.

Supported source and destination databases

You can use DTS to migrate data between the following types of MySQL databases. In this example, the source database is a self-managed MySQL database hosted on an Elastic Compute Service (ECS) instance and the destination database is an ApsaraDB MyBase for MySQL instance. You can also follow the procedure to configure data migration tasks for other types of MySQL databases.
Source database Destination database
  • Instances deployed on Alibaba Cloud
  • Self-managed databases:
    • Self-managed database with a public IP address
    • Self-managed database that is hosted on Elastic Compute Service (ECS)
    • Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway
    • Self-managed database that is connected over Database Gateway
  • Instances deployed on Alibaba Cloud
  • Self-managed databases:
    • Self-managed database with a public IP address
    • Self-managed database that is hosted on Elastic Compute Service (ECS)
    • Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway
    • Self-managed database that is connected over Database Gateway

Limits

Category Description
Limits on the source database
  • Bandwidth requirements: The server to which the source database belongs must have sufficient egress bandwidth. Otherwise, the data migration slows down.
  • The tables to be migrated must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
  • If you select tables as objects that you want to migrate and you need to edit tables (such as renaming tables or columns) in the destination database, up to 1,000 tables can be migrated in a single data migration task. If you run a task to migrate more than 1,000 tables, a request error occurs. In this case, we recommend that you split the tables and configure multiple tasks to migrate the tables, or configure a task to migrate the entire database.
  • If you want to migrate incremental data, make sure that the following requirements are met:
    • The binary logging feature must be enabled. The binlog_format parameter must be set to row. The binlog_row_image parameter must be set to full. Otherwise, error messages are returned during precheck and the data migration task fails to be started.
      Notice If the self-managed MySQL database is deployed in a dual-primary cluster, you must set log_slave_updates to ON. This ensures that DTS can obtain all binary logs.

    • If you perform only incremental data migration, the binary logs of the source database must be stored for more than 24 hours. If you perform full data migration and incremental data migration, the binary logs of the source database must be stored for at least seven days. After full data migration is completed, you can set the retention period to more than 24 hours. Otherwise, DTS may fail to obtain the binary logs and the task may fail. In extreme cases, data may be inconsistent or lost. Make sure that you set the retention period of binary logs based on the preceding requirements. Otherwise, the Service Level Agreement (SLA) of DTS does not guarantee service reliability and performance.

  • Limits on operations that are performed on the source database:
    • During schema migration and full data migration, do not perform DDL operations to change the schemas of databases or tables. Otherwise, the data migration task fails.
    • If you perform only full data migration, do not write data to the source database during data migration. Otherwise, data will be inconsistent between the source and destination databases. To ensure data consistency, we recommend that you select Schema Migration, Full Data Migration, and Incremental Data Migration as the migration types.
Other limits
  • To ensure compatibility, we recommend that you use the same engine versions for the source and destination MySQL databases.
  • 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. During full data migration, DTS uses read and write resources of the source and destination databases. This may increase the loads of the database servers.
  • 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.
  • You must make sure that the precision settings for columns of the FLOAT or DOUBLE data type meets your business requirements. 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.
  • DTS attempts to resume data migration tasks that failed within the last seven days. Before you switch workloads to the destination instance, stop or release the data migration task. You can also run the revoke command to revoke the write permissions from the accounts that are used by DTS to access the destination instance. Otherwise, the data in the source database will overwrite the data in the destination instance after the task is resumed.
Special cases
  • If the source database is a self-managed MySQL database, take note of the following points:
    • If a failover is performed on the source database when the data migration task is running, the task fails.
    • DTS calculates migration latency based on the timestamp of the latest migrated data in the destination database and the current timestamp in the source database. If no DML operation is performed on the source database for a long time, the migration latency may be inaccurate. If the latency of the task is too high, you can perform a DML operation on the source database to update the latency.
      Note If you select an entire database as the object that you want to migrate, you can create a heartbeat table. The heartbeat table is updated or receives data every second.
  • If the destination database is a database in the ApsaraDB MyBase for MySQL instance, take note of the following points:

    DTS automatically creates a destination database in the ApsaraDB MyBase for MySQL instance. However, if the name of the source database does not meet the naming conventions specified in ApsaraDB MyBase for MySQL, you must create a database in the ApsaraDB MyBase for MySQL instance before you configure the migration task. For more information, see Create a database.

Billing

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

Migration types

  • Schema migration

    DTS migrates the schemas of required objects from the source database to the destination database.

    Note
    • DTS supports schema migration for the following types of objects: table, view, trigger, stored procedure, and function.
    • 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. To call a view, stored procedure, or function of the destination database, you must grant the read and write permissions to INVOKER.
  • Full data migration

    DTS migrates historical data of required objects from the source database to the destination database.

  • Incremental data migration

    After full data migration is completed, DTS migrates incremental data from the source database to the destination database. Incremental data migration ensures service continuity when you migrate data between self-managed databases.

SQL operations that can be performed for incremental data migration

Operation type SQL statement
DML INSERT, UPDATE, and DELETE
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
Self-managed MySQL database that is hosted on an ECS instance The SELECT permission The SELECT permission Incremental data migration: the SELECT permission on the objects to be migrated

The REPLICATION CLIENT, REPLICATION SLAVE, and SHOW VIEW permissions
ApsaraDB MyBase for MySQL instance The read and write permissions

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

Procedure

  1. Go to the Data Migration page of the new DTS console.
    Note You can also log on to the Data Management (DMS) console. In the top navigation bar, click DTS.
  2. In the upper-left corner of the page, select the region in which the data migration instance resides.
    Region
  3. Click Create Task. Configure source and destination databases.
    Warning After you select the source and destination instances, we recommend that you read the limits displayed at the top of the page. This helps you create and run the data migration task.
    Configure 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 to identify the task. You do not need to use a unique task name.
    Source Database Select Instance
    You have the option to select an existing instance based on your requirements.
    • If you use an existing instance, DTS automatically applies the parameter settings of the instance.
    • If you do not use an existing instance, you must configure the following parameters.
    Database Type Select MySQL.
    Access Method Select an instance type based on the location where the source database is deployed. In this example, select Self-managed Database on ECS.
    Instance Region Select the region where the source MySQL database is deployed.
    ECS Instance ID Select the ECS instance from which you want to migrate data.
    Port Number Enter the service port number of the source MySQL database. The port must be accessible over the Internet. The default port number is 3306.
    Database Account Enter the account of the source MySQL database. For 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.

    Encryption Select Non-encrypted or SSL-encrypted based on data security requirements. In this example, select Non-encrypted.
    Destination Database Select Instance
    You have the option to select an existing instance based on your requirements.
    • If you use an existing instance, DTS automatically applies the parameter settings of the instance.
    • If you do not use an existing instance, you must configure the following parameters.
    Database Type Select MySQL.
    Access Method Select Cloud Instance.
    Instance Region Select the region where the destination ApsaraDB MyBase for MySQL instance is deployed.
    RDS Instance ID Select the ID of the destination ApsaraDB MyBase for MySQL instance.
    Database Account Enter the database account of the destination ApsaraDB MyBase for MySQL instance. For 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.

    Encryption Select Non-encrypted or SSL-encrypted based on data security requirements. In this example, select Non-encrypted.
  4. After you specify the parameters, click Test Connectivity and Proceed.
  5. If a whitelist is configured for your self-managed database, you must add the CIDR blocks of DTS servers to the whitelist. Then, click Test Connectivity and Proceed.
    Note
    • If the source or destination database is a database instance deployed on Alibaba Cloud, such as an ApsaraDB MyBase for MySQL instance, or is a self-managed database hosted on an ECS instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database.
    • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database instance or ECS security group rules, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the password strength of your account, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
    • After the DTS task is complete or released, we recommend that you manually detect and delete the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
  6. If a whitelist is configured for your self-managed database, you must add the CIDR blocks of DTS servers to the whitelist. Then, click Test Connectivity and Proceed.
    Warning
    • If the source or destination database instance is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, or is a self-managed database hosted on Elastic Compute Service (ECS), DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database.
    • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database instance or ECS security group rules, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhance the security of your account and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
    • After the DTS task is completed or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
  7. Select objects for the task and configure advanced settings.
    • Basic settings
      Parameter Description
      Task Stages
      • To perform only full data migration, select Schema Migration and Full Data Migration.
      • To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.
      Note If Incremental Data Migration is not selected, we recommend that you do not write data to the source instance during data migration. This ensures data consistency between the source and destination instances.
      Processing Mode of Conflicting Tables

      • Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain identical table names, the precheck is passed. Otherwise, an error is returned during precheck and the data migration task cannot be started.

        Note You can use the object name mapping feature to rename the tables that are migrated to the destination database. You can use this feature if the source and destination databases contain identical table names and the tables in the destination database cannot be deleted or renamed. For more information, see Map object names.
      • Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases.
        Warning If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to potential risks.
        • If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database.
        • If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails.
      Select Objects

      Select one or more objects from the Source Objects section and click the Rightwards arrow icon to add the objects to the Selected Objects section.

      Note
      • To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
      • To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
      Note If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
    • Advanced settings
      Parameter Description
      Set Alerts
      Specify whether to set alerts for the data migration task. If the task fails or the migration latency exceeds the threshold, the alert contacts will receive notifications.
      • Select No if you do not want to set alerts.
      • Select Yes to set alerts. In this case, you must also set the alert threshold and alert contacts.
      Capitalization of Object Names in Destination Instance

      Specify the capitalization of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.

      Replicate Temporary Tables When DMS Performs DDL Operations
      If you use Data Management (DMS) to perform online DDL operations on the source database, you can specify whether to migrate temporary tables generated by online DDL operations.
      • Yes: DTS migrates the data of temporary tables generated by online DDL operations.
        Note If online DDL operations generate a large amount of data, the migration task may be delayed.
      • No: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL data of the source database is migrated.
        Note If you select No, the tables in the destination database may be locked.
      Retry Time for Failed Connections
      Specify the retry time range for failed connections. Valid values: 10 to 720. Unit: minutes. Default value: 720. We recommend that you set the retry time range to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.
      Note
      • If an instance serves as the source or destination database of multiple data synchronization tasks, the value that is set later takes precedence.
      • When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
  8. After you specify the preceding parameters, click Next: Save Task Settings and Precheck.
    Note
    • Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.
    • If the task fails to pass the precheck, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  9. Wait until the Success Rate becomes 100%. Then, click Next: Purchase Instance.
  10. On the Purchase Instance page, specify the Instance Class parameter for the data migration instance. The following table describes the parameter.
    Section Parameter Description
    Parameters Instance Class

    DTS provides various migration specifications that provide different performance. The migration speed varies based on the migration specifications that you select. You can select a migration specification based on your business scenario. For more information, see Specifications of data migration instances.

  11. Read and select Data Transmission Service (Pay-as-you-go) Service Terms.
  12. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.

What to do next

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