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    Data Transmission Service:Migrate PolarDB-X 1.0 to DataHub

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    Data Transmission Service:Migrate PolarDB-X 1.0 to DataHub

    Last Updated:Jun 27, 2026

    This topic describes how to use Data Transmission Service (DTS) to migrate data from a PolarDB-X 1.0 instance to a DataHub project.

    Prerequisites

    • You have created a source PolarDB-X 1.0 instance. For more information, see Create a PolarDB-X 1.0 instance.

      Note

      The PolarDB-X 1.0 instance must use ApsaraDB RDS for MySQL as its storage type. This includes both privately customized and separately purchased RDS instances. PolarDB for MySQL is not supported.

    • You have activated DataHub and created a project to receive the migrated data. For more information, see Quick start (synchronization example) and Manage projects.

    Limitations

    Type

    Description

    Source database limitations

    • If you migrate objects at the table level and need to edit them, for example, by mapping column names, a single data migration task supports a maximum of 1,000 tables. If you exceed this limit, the task submission will fail. In this case, split the tables into multiple data migration tasks or configure a task to migrate the entire database.

    • For incremental migration, the following binary log requirements apply:

      • The binary log must be enabled, and the binlog_row_image parameter must be set to full. Otherwise, the precheck fails and the data migration task cannot start.

      • If your task includes incremental migration, DTS requires the source database to retain its local binary log for at least 24 hours. We recommend a retention period of 7 days. If the retention period is insufficient, DTS may fail to obtain the binary log. This can cause the task to fail and, in extreme cases, lead to data inconsistency or loss. The SLA does not cover issues caused by a binary log retention period shorter than the required duration.

    • DTS does not support data migration from PolarDB-X 1.0 read-only instances.

    • Operational restrictions on the source database:

      • During data migration, do not perform scale-out, scale-in, hot table migration, shard key changes, or DDL changes. Otherwise, the data migration task fails.

        Note

        During the full migration phase, DTS queries the source database. This creates a metadata lock, which may block DDL operations on the source database.

      • During full and incremental migration, DTS temporarily disables constraint checks and foreign key cascading operations at the session level. If cascading update or delete operations occur on the source database while the task is running, data inconsistency may occur.

      • If you perform only a full data migration, do not write new data to the source database. Otherwise, data inconsistency will occur between the source and destination databases. To maintain real-time data consistency, select schema migration, full data migration, and incremental data migration.

    • The source PolarDB-X 1.0 instance must be version 5.2 or later.

    • Do not change the type of a broadcast table in the source PolarDB-X 1.0 instance while a DTS migration task is running (for example, from a broadcast table to a single table or a sharded table). If you need to change the table type, stop the migration task. After the change is complete, reconfigure the migration task.

    Other limitations

    • Schema migration, full migration, and incremental migration are supported.

    • The maximum length for a single String field in the target DataHub is 2 MB.

    • DTS relies on the continuity of XA transactions in the source PolarDB-X 1.0 instance to ensure data consistency for incremental migration tasks. If the continuity of XA transactions is broken, for example, during a disaster recovery scenario for the incremental data capture module, uncommitted XA transactions may be lost.

    • Before you migrate data, evaluate the performance of the source and target databases. We also recommend performing data migration during off-peak hours. Otherwise, the database load may increase.

    • DTS attempts to resume a failed task within seven days. Therefore, before the cutover to the target instance, you must end or release the task. Alternatively, revoke the write permissions from the account that DTS uses to access the target instance by using the revoke command. This prevents the source data from overwriting data in the target instance if the task automatically resumes.

    • If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters.

      Note

      Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters.

    Additional considerations

    DTS periodically updates the dts_health_check.ha_health_check table in the source database to advance the binlog position.

    Billing

    Migration type

    Instance configuration fee

    Internet traffic fee

    Schema migration

    Free of charge.

    Free of charge.

    Incremental migration

    Fees apply. For more information, see Billing overview.

    Migration types

    • Schema Migration

      DTS migrates the schema definitions of objects from the source database to the destination database.

    • Incremental Migration

      DTS migrates incremental data changes from the source database to the destination database. This enables a smooth migration with zero downtime for your applications.

    Supported SQL operations

    Operation type

    SQL statements

    DML

    INSERT, UPDATE, DELETE

    Account permissions

    Database

    Schema migration

    Incremental migration

    PolarDB-X 1.0 instance

    SELECT permission

    Read and write permissions for the migration objects.

    Note

    For information about how to grant permissions, see Manage accounts.

    Data type mappings

    For more information, see Data type mappings for schema migration.

    Procedure

    1. Navigate to the migration task list page for the destination region using one of the following methods.

      From the DTS console

      1. Log on to the Data Transmission Service (DTS) console.

      2. In the navigation pane on the left, click Data Migration.

      3. In the upper-left corner of the page, select the region where the migration instance is located.

      From the DMS console

      Note

      The actual operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode console and Customize the layout and style of the DMS console.

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

      2. In the top menu bar, choose Data + AI > Data Transmission (DTS) > Data Migration.

      3. To the right of Data Migration Tasks, select the region where the migration instance is located.

    2. Click Create Task to navigate to the task configuration page.

    3. Configure the source and destination databases.

      Warning

      After you select the source and destination instances, carefully read the Limits displayed at the top of the page to ensure your migration task can be created and run successfully.

      Category

      Setting

      Description

      Basic settings

      Task Name

      DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.

      Source Database

      Select Existing Connection

      • To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured.

        Note

        In the DMS console, this parameter is named Select a DMS database instance..

      • If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select PolarDB-X 1.0.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the source PolarDB-X 1.0 instance is located.

      Replicate Data Across Alibaba Cloud Accounts

      This tutorial demonstrates migration within the same Alibaba Cloud account. Select No.

      Instance ID

      Select the ID of the source PolarDB-X 1.0 instance.

      Database Account

      Enter the database account for the source PolarDB-X 1.0 instance. For permission requirements, see Account permissions.

      Database Password

      Enter the password for the database account.

      Destination Database

      Select Existing Connection

      • To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured.

        Note

        In the DMS console, this parameter is named Select a DMS database instance..

      • If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.

      Database Type

      Select DataHub.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the destination DataHub project is located.

      Project

      Select the ID of the destination DataHub project.

    4. After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page.

      Note

      Ensure that the DTS service IP address segments are automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add DTS server IP addresses to a whitelist.

    5. Configure the task objects.

      1. On the Configure Objects page, configure the objects that you want to migrate.

        Setting

        Description

        Migration Types

        When you migrate data from PolarDB-X 1.0 to DataHub, only Schema Migration and Incremental Data Migration are supported. Select the migration types based on your business requirements.

        Note

        • If you select Schema Migration, foreign keys from the source database are also migrated.

        • To ensure data consistency, do not write new data to the source instance during the migration if you do not select Incremental Data Migration.

        Processing Mode for Existing Destination Tables

        • Precheck and Report Errors: Checks if a table with the same name exists in the destination database. If no such table exists, the precheck passes. If a table with the same name exists, the precheck reports an error and the migration task does not start.

          Note

          If you cannot easily delete or rename the table in the destination database, you can change its name in the destination database. For more information, see Schema, table, and column name mapping.

        • Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database.

          Warning

          Selecting Ignore Errors and Proceed may cause data inconsistency and pose risks to your business, such as:

          • If the table structures are identical and records share a primary key:

            During incremental migration, Data Transmission Service (DTS) overwrites the record in the destination database with the record from the source database.

          • If the table structures are different, only some columns of data might be migrated, or the migration might fail. Proceed with caution.

        Naming Rules of Additional Columns

        When migrating data to DataHub, DTS adds several additional columns to the destination tables. If these additional column names conflict with existing column names, the migration fails. Select New Rule or Previous Rule based on your requirements.

        Warning

        Before you select a rule, assess whether name conflicts may occur between the additional columns and your existing columns. For more information about the rules and definitions, see Additional column names and definitions.

        Capitalization of Object Names in Destination Instance

        You can configure the capitalization policy for database, table, and column names in the destination instance. By default, the DTS policy is used. You can also choose to match the default policy of the source or destination database. For more information, see Capitalization of object names in the destination instance.

        Source Objects

        In the Source Objects box, click the objects to migrate, and then click Right arrow to move them to the Selected Objects box.

        Note

        We recommend that you select objects to migrate at the table level. If you select an entire database, changes such as adding or deleting tables in that database will not be migrated to the destination database.

        Selected Objects
        Note

        • Using the object name mapping feature can cause the migration of dependent objects to fail.

        • To filter data by using a WHERE clause, right-click a table in the Selected Objects box and specify the filter condition in the dialog box that appears. For more information, see Set filter conditions.

        • To select SQL operations to migrate at the database or table level, right-click an object in the Selected Objects box and choose the desired operations.

      2. Click Next: Advanced Settings to configure advanced parameters.

        Setting

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS schedules tasks on a shared cluster. You do not need to select one. If you want more stable tasks, you can purchase a dedicated cluster to run DTS migration tasks.

        Retry Time for Failed Connections

        After the migration task starts, if the connection to the source or destination database fails, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1440 minutes. We recommend that you set the duration to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails.

        Note

        • For multiple DTS instances that share the same source or destination, the network retry time is determined by the setting of the last created task.

        • Because you are charged for the task during the connection retry period, we recommend that you customize the retry time based on your business needs, or release the DTS instance as soon as possible after the source and destination database instances are released.

        Retry Time for Other Issues

        After the migration task starts, if a non-connectivity issue, such as a DDL or DML execution exception, occurs in the source or destination database, DTS reports an error and immediately begins to retry the operation. The default retry duration is 10 minutes. You can customize the retry time to a value from 1 to 1440 minutes. We recommend that you set the duration to more than 10 minutes. If the related operations succeed within the specified retry duration, the migration task automatically resumes. Otherwise, the task fails.

        Important

        The value of Retry Time for Other Issues must be less than the value of Retry Time for Failed Connections.

        Enable Throttling for Incremental Data Migration

        If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database.

        Note

        • This configuration item is available only if you select Incremental Data Migration for Migration Types.

        • You can also adjust the incremental migration speed after the migration instance is running.

        Environment Tag

        You can select an environment tag to identify the instance. This is not required for this tutorial.

        Configure ETL

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

        Monitoring and Alerting

        Select whether to set alerts and receive alert notifications based on your business needs.

        • No: Does not set an alert.

        • Yes: Configure alerts by setting an alert threshold and an alert notifications. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

    6. Save the task and run a precheck.

      • To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.

      • If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

      Note

      • Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.

      • If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.

      • If a warning is reported during the precheck:

        • For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.

        • For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.

    7. Purchase the migration instance.

      1. When the Success Rate is 100%, click Next: Purchase Instance.

      2. On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

        Category

        Parameter

        Description

        New Instance Class

        Resource Group Settings

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

        Instance Class

        DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

      3. After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.

      4. Click Buy and Start. In the OK dialog box that appears, click OK.

        You can view the progress of the migration task on the Data Migration Tasks list page.

        Note

        • If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.

        • If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.