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ApsaraDB RDS:Migrate data from a self-managed MySQL database to an ApsaraDB RDS for MySQL instance

Last Updated:Aug 13, 2024

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

Note

Before you use DTS, make sure that DTS has the permissions to access Alibaba Cloud resources. For more information, see Authorize DTS to access Alibaba Cloud resources.

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 with a public IP address and the destination database is hosted in an ApsaraDB RDS for MySQL instance. You can follow the procedure to configure data migration tasks for other types of MySQL databases.

Source database

Destination database

  • ApsaraDB RDS for MySQL instance

  • 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
  • ApsaraDB RDS for MySQL instance

  • 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

Prerequisites

  • The engine version of the self-managed MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.

  • The CIDR blocks of DTS servers are added to the IP address whitelist of the source MySQL database if the database is an on-premises database. This setting ensures that DTS servers can access the source MySQL database. For more information, see Add the CIDR blocks of DTS servers.

  • The destination ApsaraDB RDS for MySQL instance is created. For more information, see Create an ApsaraDB RDS for MySQL instance.

  • The available storage space of the ApsaraDB RDS for MySQL instance is larger than the total size of the data in the self-managed MySQL database.

Limits

Note
  • During schema migration, DTS migrates foreign keys from the source database to the destination database.

  • During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If you perform the cascade and delete operations on the source database during data migration, data inconsistency may occur.

Category

Description

Limits on the source database

  • The server on which the source database is deployed must have sufficient outbound bandwidth. Otherwise, the data migration speed decreases.

  • 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 the objects to be migrated and you want to modify the tables in the destination database, such as renaming tables or columns, you can migrate up to 1,000 tables 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 configure multiple tasks to migrate the tables or configure a task to migrate the entire database.

  • If you want to migrate incremental data, the following requirements for binary logs must be met:

    • The binary logging feature is enabled. The binlog_format parameter is set to row and the binlog_row_image parameter is set to full. Otherwise, error messages are returned during the precheck and the data migration task fails to be started.

      Important

      If the source database is a self-managed MySQL database deployed in a dual-primary cluster, you must set the log_slave_updates parameter to ON. This ensures that DTS can obtain all binary logs.

    • The binary logs of the source database must be stored for at least seven days. Otherwise, DTS may fail to obtain the binary logs and the task may fail. In exceptional circumstances, data inconsistency or loss may occur. Make sure that you configure the retention period of binary logs based on the preceding requirements. Otherwise, the service reliability or performance stated in the Service Level Agreement (SLA) of DTS may not be guaranteed.

  • Limits on operations to be performed on the source database:

    • During schema migration and full data migration, do not execute DDL statements 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 inconsistency between the source and destination databases occurs. 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, the versions of the source and destination MySQL databases must be the same.

  • 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 the read and write resources of the source and destination databases. This may increase the loads on 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 meet 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 columns of the FLOAT data type to 38 digits and the precision for columns of 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 database, you must stop or release the failed task. You can also execute the REVOKE statement to revoke the write permissions from the accounts that are used by DTS to access the destination database. Otherwise, the data in the source database overwrites the data in the destination database after a failed task is resumed.

  • If DDL statements fail to be executed in the destination database, the DTS task continues to run. You can view the DDL statements that fail to be executed in task logs. For more information about how to view task logs, see View task logs.

  • If you write column names that differ only in capitalization to the same table in the destination MySQL database, the data migration result may not meet your expectations because the column names in MySQL databases are not case-sensitive.

  • After data migration is complete, we recommend that you run the analyze table <table name> command to check whether data is written to the destination table. For example, if a high-availability (HA) switchover is triggered in the source MySQL database, data may be written only to the memory. As a result, data loss occurs.

  • If the source database is an ApsaraDB RDS for MySQL instance for which the EncDB feature is enabled, full data migration cannot be performed.

Special cases

  • If the source database is a self-managed MySQL database, take note of the following limits:

    • If you perform a primary/secondary switchover 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 data migration task is excessively 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 to be migrated, you can create a heartbeat table. The heartbeat table is updated or receives data every second.

    • DTS executes the CREATE DATABASE IF NOT EXISTS `test` statement in the source database as scheduled to move forward the binary log file position.

  • If the source database is an Apsara RDS for MySQL instance, take note of the following limit:

    In incremental data migration, an ApsaraDB RDS for MySQL instance that does not record transaction logs, such as a read-only ApsaraDB RDS for MySQL V5.6 instance, cannot be used as the source database.

  • If the destination database is an ApsaraDB RDS for MySQL instance, take note of the following limit:

    DTS automatically creates a database in the destination ApsaraDB RDS for MySQL instance. However, if the name of the source database does not comply with the database naming conventions of ApsaraDB RDS for MySQL, you must manually create a database in the destination ApsaraDB RDS for MySQL instance before you configure the data migration task. For more information, see Manage databases.

Billing

Migration typeInstance configuration feeInternet traffic fee
Schema migration and full data migrationFree of charge. Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview.
Incremental data migrationCharged. For more information, see Billing overview.

Migration types

  • Schema migration

    Data Transmission Service (DTS) migrates the schemas of the selected objects from the source database to the destination database.

    Note
    • DTS supports schema migration for the following types of objects: tables, views, triggers, stored procedures, and stored functions.

    • During schema migration, DTS changes the value of the SECURITY attribute from DEFINER to INVOKER for views, stored procedures, and stored functions.

    • DTS does not migrate user information. To call a view, stored procedure, or stored function of the destination database, you must grant the read and write permissions to INVOKER.

  • Full data migration

    DTS migrates the historical data of the selected 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 allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.

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

    Important

    RENAME TABLE operations may cause data inconsistency between the source and destination databases. For example, if you select a table as the object to be migrated and rename the table during data migration, the data of this table is not migrated to the destination database. To prevent this situation, select the database to which this table belongs as the object to be migrated when you configure the data migration task. Make sure that the databases to which the table belongs before and after the RENAME TABLE operation are added to the objects to be migrated.

  • TRUNCATE TABLE

Permissions required for database accounts

Database

Schema migration

Full data migration

Incremental data migration

Self-managed MySQL database

SELECT permission

SELECT permission

SELECT permission on the objects to be migrated

REPLICATION CLIENT, REPLICATION SLAVE, and SHOW VIEW permissions

Permissions to create databases and tables. The permissions allow DTS to create a database named dts to record heartbeat data during migration.

ApsaraDB RDS for MySQL instance

Read and write permissions

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

Procedure

  1. Go to the Data Migration page.

    1. Log on to the Data Management (DMS) console.

    2. In the top navigation bar, move the pointer over DTS.

    3. Choose DTS (DTS) > Data Migration.

    Note
  2. From the drop-down list on the right side of Data Migration Tasks, select the region in which your data migration instance resides.

    Note

    If you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.

  3. Click Create Task. In the Create Task wizard, configure the source and destination databases. The following table describes the parameters.

    Warning

    After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

    Section

    Parameter

    Description

    None

    Task Name

    The name of the task. DTS automatically assigns a name to the task. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.

    Source Database

    Select a DMS database instance

    The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements.

    • If you select an existing instance, DTS automatically populates the parameters for the database.

    • If you do not select an existing instance, you must configure parameters for the source database.

    Database Type

    The type of the source database. Select MySQL.

    Access Method

    The access method of the source database. Select an access method based on the deployment location of the source database. In this example, Public IP Address is selected.

    Note

    If you select other access methods, you must set up the environment that is required for the self-managed database. For more information, see Preparation overview.

    Instance Region

    The region in which the source MySQL database resides.

    Hostname or IP address

    The endpoint that is used to access the source MySQL database. In this example, the public IP address is entered.

    Port Number

    The service port number of the source MySQL database. The port must be accessible over the Internet. Default value: 3306.

    Database Account

    The account of the source MySQL database. For more information about the permissions that are required for the account, see Permissions required for database accounts.

    Database Password

    The password of the database account.

    Destination Database

    Select a DMS database instance

    The database instance that you want to use. You can choose whether to use an existing instance based on your business requirements.

    • If you select an existing instance, DTS automatically populates the parameters for the instance.

    • If you do not select an existing instance, you must configure parameters for the destination database.

    Database Type

    The type of the destination database. Select MySQL.

    Access Method

    The access method of the destination instance. In this example, select Alibaba Cloud Instance.

    Instance Region

    The region in which the destination ApsaraDB RDS for MySQL instance resides.

    RDS Instance ID

    The ID of the destination ApsaraDB RDS for MySQL instance.

    Database Account

    The database account of the destination instance. For information about the permissions that are required for the account, see Permissions required for database accounts.

    Database Password

    The password of the database account.

    Encryption

    Specifies whether to encrypt the connection to the source database instance. Select Non-encrypted or SSL-encrypted based on your business requirements. If you select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data migration task. For more information, see Configure the SSL encryption feature.

  4. In the lower part of the page, click Test Connectivity and Proceed.

  5. If an IP address whitelist is configured for your self-managed database, add the CIDR blocks of DTS servers to the IP address whitelist. Then, click Test Connectivity and Proceed.

    Warning

    If the public CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database instance or to the security group rules of an ECS instance, 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 security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or security group rules and forbidding unauthorized CIDR blocks, or connecting the database instance to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

  6. Configure the objects to be migrated and advanced settings.

    Parameter

    Description

    Migration Types

    • 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 you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.

    Processing Mode of Conflicting Tables

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

      Note

      If the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. 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 the following 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. Proceed with caution.

    Capitalization of Object Names in Destination Instance

    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.

    Source Objects

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

    Note

    You can select columns, tables, or schemas as the objects to be migrated. If you select tables or columns as the objects to be migrated, DTS does not migrate other objects, such as views, triggers, or stored procedures, to the destination database.

    Selected Objects

    • 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.

    • To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Set filter conditions.

    • To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to migrate. For more information about the SQL operations that can be migrated, see SQL operations that can be performed for incremental data migration.

  7. Click Next: Advanced Settings to configure advanced settings.

    Parameter

    Description

    Monitoring and Alerting

    Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values:

    Copy the temporary table of the Online DDL tool that is generated in the source table to the destination database

    If you use DMS or the gh-ost tool to perform online DDL operations on the source database, you can specify whether to migrate the data of temporary tables generated by online DDL operations. Valid values:

    Important

    You cannot use tools such as pt-online-schema-change to perform online DDL operations on the source database. Otherwise, the DTS task fails.

    • Yes: DTS migrates the data of temporary tables generated by online DDL operations.

      Note

      If online DDL operations generate a large amount of data, latency may occur for the data migration task.

    • No, Adapt to DMS Online DDL: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using DMS are migrated.

      Note

      If you select No, Adapt to DMS Online DDL, the tables in the destination database may be locked.

    • No, Adapt to gh-ost: DTS does not migrate the data of temporary tables generated by online DDL operations. Only the original DDL operations that are performed by using the gh-ost tool are migrated. You can use the default or custom regular expressions to filter out the shadow tables of the gh-ost tool and tables that are not required.

      Note

      If you select No, Adapt to gh-ost, the tables in the destination database may be locked.

    Retry Time for Failed Connections

    The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails.
    Note
    • If you set different retry time ranges for multiple data migration tasks that have the same source or destination database, the shortest retry time range that is set 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 requirements. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.

    Configure ETL

    Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values:

    Whether to delete SQL operations on heartbeat tables of forward and reverse tasks

    Specifies whether to write SQL operations on heartbeat tables to the source database while the DTS instance is running.

    • Yes: does not write SQL operations on heartbeat tables. In this case, a latency of the DTS instance may be displayed.

    • No: writes SQL operations on heartbeat tables. In this case, specific features such as physical backup and cloning of the source database may be affected.

  8. In the lower part of the page, click Next: Save Task Settings and Precheck.

    You can move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters to view the parameters to be specified when you call the relevant API operation to configure the DTS task.

    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, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.

    • If an alert is generated for an item during the precheck, perform the following operations based on the scenario:

      • If the alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.

      • If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.

  9. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

  10. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

    Section

    Parameter

    Description

    New Instance Class

    Resource Group Settings

    The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?

    Instance Class

    DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Instance classes of data migration instances.

  11. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

  12. Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.

FAQ

What do I do if the "JDBC: [conn_error, cause: null, message from server: "Host 'XXX' is not allowed to connect to this MySQL server"]; PING: []; TELNET: []; requestId=[XXX]" error message is displayed during a connectivity test?

The error message indicates that a Java Database Connectivity (JDBC) exception occurs. In this case, you must check the username, password, and permissions of the account for JDBC. Alternatively, you can use a privileged account to test connectivity.