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    Data Transmission Service:Migrate from PolarDB for MySQL to AnalyticDB for PostgreSQL

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    Data Transmission Service:Migrate from PolarDB for MySQL to AnalyticDB for PostgreSQL

    Last Updated:Aug 21, 2026

    Use Data Transmission Service (DTS) to migrate data from a PolarDB for MySQL cluster to an AnalyticDB for PostgreSQL instance.

    Prerequisites

    • A target AnalyticDB for PostgreSQL instance must exist. For more information, see Create an AnalyticDB for PostgreSQL instance.

    • The target AnalyticDB for PostgreSQL instance must have more available storage space than the storage used by the source PolarDB for MySQL cluster.

    Usage notes

    Note

    • DTS migrates foreign keys during schema migration.

    • During full and incremental data migration, DTS temporarily disables constraint checks and foreign key cascades at the session level. Cascade updates or deletes on the source database while the task runs may cause data inconsistency.

    Type

    Description

    Source database limitations

    • Bandwidth requirements: The server that hosts the source database must have sufficient outbound bandwidth. Otherwise, the data migration speed will be affected.

    • The tables to be migrated must have a primary key or a unique constraint, and the values in the columns must be unique. Otherwise, duplicate data may appear in the destination database.

    • If you migrate data at the table level and need to perform edits such as column mapping, a single data migration task supports a maximum of 1,000 tables. To migrate more tables, we recommend splitting them into multiple tasks or configuring a task to migrate the entire database. Otherwise, a request error may occur after you submit the task.

    • If you perform incremental migration:

      • You must enable binary logging and set the loose_polar_log_bin parameter to on. Otherwise, the precheck reports an error and the data migration task cannot start. For more information about how to enable binary logging and modify parameters, see Enable binary logging and Modify parameters.

        Note

        Enabling binary logging for a PolarDB for MySQL cluster consumes storage space and incurs storage fees.

      • The binary logs of the PolarDB for MySQL cluster must be retained for at least 3 days. We recommend a retention period of 7 days. Otherwise, DTS may fail to obtain the binary logs, which can cause the task to fail. In extreme cases, this can lead to data inconsistency or data loss. Issues caused by a binary log retention period shorter than the DTS requirement are not covered by the DTS Service-Level Agreement (SLA).

        Note

        For more information about how to set the retention period for binary logs of a PolarDB for MySQL cluster, see Modify the retention period.

    • During the schema migration and full migration phases, do not perform DDL operations that change the database or table schema. Otherwise, the data migration task will fail.

      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.

    • 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.

    • If the data to be migrated from the source database contains the date 0000-00-00 00:00:00, the task may fail.

      Note

      When DTS migrates the date data to the destination database, the data is converted to null. You can temporarily change the data in the source database to 0001-01-01 00:00:00 or set the corresponding field in the destination database to be nullable.

    Other limitations

    • DTS cannot migrate read-only nodes of a source PolarDB for MySQL cluster.

    • DTS does not support the migration of OSS external tables from the source PolarDB for MySQL instance.

    • Migration of PARTITION, VIEW, PROCEDURE, FUNCTION, TRIGGER, FK, and INDEX objects is not supported.

    • Only table-level migration is supported. Append-optimized (AO) tables are not supported as destination tables.

    • DTS does not support primary/standby switchover scenarios for the database instance during full data migration. In such a scenario, reconfigure the migration task promptly.

    • If your source database uses temporary-table-mode online DDL operations—including multi-table merge scenarios—or adds function-based indexes to unique key columns, data loss or task failure may occur on the destination database.

    • If you use column mapping for a partial table migration or if the source and destination table schemas are inconsistent, data loss occurs for columns that exist in the source table but not in the destination table.

    • If a table to be migrated has a primary key, the primary key column in the destination table must be the same as that in the source table. If a table to be migrated does not have a primary key, the primary key column in the destination table must be the same as the distribution key.

    • The unique key of the destination table, including the primary key column, must contain all columns of the distribution key.

    • Full data migration consumes read and write resources on the source and destination databases, which can increase their load. We recommend evaluating the performance of both databases and performing the migration during off-peak hours.

    • For columns of the FLOAT or DOUBLE data type, DTS uses ROUND(COLUMN,PRECISION) to read values. If you do not explicitly define the precision, DTS uses a default migration precision of 38 digits for FLOAT and 308 digits for DOUBLE. Make sure the precision meets your requirements.

    • DTS attempts to resume a failed migration task within seven days. Before you perform a workload switchover to the destination instance, you must stop or release the migration instance. Alternatively, you can run the REVOKE command to revoke the write permissions from the account that DTS uses to access the destination instance. This prevents the task from automatically resuming and overwriting data in the destination instance.

    • 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.

    Other usage notes

    • DTS periodically executes the CREATE DATABASE IF NOT EXISTS test command in the source database to advance the binlog position.

    • During full data migration, concurrent INSERT operations cause table fragmentation in the destination database. As a result, tables in the destination database consume more storage space than those in the source instance after full data migration is complete.

    Billing

    Migration type

    Instance configuration fee

    Internet traffic fee

    Schema migration and full data migration

    Free of charge.

    When the Access Method parameter of the destination database is set to Public IP Address, you are charged for Internet traffic. For more information, see Billing overview.

    Incremental data migration

    Charged. For more information, see Billing overview.

    Migration types

    • Schema migration

      DTS migrates object schemas from the source database to the destination database.

    • Full data migration

      DTS migrates all existing data from the source database to the destination database.

    • Incremental data migration

      Building on the full data migration, DTS migrates incremental data from the source database to the destination database. This process ensures a smooth migration with minimal downtime for your self-managed applications.

    SQL operations for incremental migration

    Type

    SQL statement

    DML

    INSERT, UPDATE, and DELETE

    Note

    The system automatically converts an UPDATE statement to a REPLACE INTO statement when writing to the destination AnalyticDB for PostgreSQL instance. If an UPDATE statement modifies a primary key, the system converts it into DELETE and INSERT statements.

    DDL

    CREATE TABLE, ALTER TABLE, TRUNCATE TABLE, and DROP TABLE

    Permission requirements for database accounts

    Database

    Permission requirements

    References

    PolarDB for MySQL cluster

    Read permissions on the objects to be migrated

    Create and manage a database account

    AnalyticDB for PostgreSQL

    Read and write permissions on the destination database for the objects to be migrated

    Create and manage users

    Note

    You can also use an account with the RDS_SUPERUSER permission. For instructions, see Manage users and permissions.

    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.

      Section

      Parameter

      Description

      N/A

      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 for MySQL.

      Access Method

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region of the source PolarDB for MySQL instance.

      Cross-account

      This example is for a migration within the same Alibaba Cloud account. Select No.

      PolarDB Cluster ID

      Select the ID of the source PolarDB for MySQL instance.

      Database Account

      Enter the database account of the source PolarDB for MySQL instance. For information about the required permissions, see Permission requirements for database accounts.

      Database Password

      Enter the password for the database account.

      Encryption

      Select a connection type as needed. For more information about the SSL encryption feature, see Enable SSL encryption.

      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 AnalyticDB for PostgreSQL.

      Access Method

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region of the destination AnalyticDB for PostgreSQL instance.

      Instance ID

      Select the ID of the destination AnalyticDB for PostgreSQL instance.

      Database Name

      Enter the name of the database in the destination AnalyticDB for PostgreSQL instance where you want to migrate the objects.

      Database Account

      Enter the database account of the destination AnalyticDB for PostgreSQL instance. For information about the required permissions, see Permission requirements for database accounts.

      Database Password

      Enter the password for the database account.

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

      Note

      • Ensure that the IP address segment of the DTS service is 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.

      • If the source or destination database is a self-managed database (the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.

    5. Configure the task objects.

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

        Parameter

        Description

        Migration Types

        • If you only need to perform a full migration, select both Schema Migration and Full Data Migration.

        • To perform a migration with no downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration.

        Note

        • If you do not select Schema Migration, you must ensure that a database and tables to receive the data exist in the destination database. You can also use the object name mapping feature in the Selected Objects box as needed.

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

        Processing Mode for Existing Destination Tables

        • Precheck and Report Errors: DTS checks for tables with the same names in the destination database. The precheck passes if no such tables are found. If duplicates exist, an error is reported during the precheck and the data migration task cannot be started.

          Note

          If you cannot delete or rename the tables in the destination database, you can change the names of the tables in the destination database. For more information, see Map table and column names.

        • Clear Destination Table: Clears existing data from the destination tables. Proceed with caution.

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

          Warning

          If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to risks. For example:

          • If the source and destination databases have the same schema and a record in the destination database has the same primary key value as a record in the source database:

            • During a full migration, DTS retains the record in the destination database and does not migrate the record from the source database.

            • During an incremental migration, the record from the source database overwrites the record in the destination database.

          • If the source and destination databases have different schemas, data may fail to be initialized, only some columns can be migrated, or the migration may fail.

        Select DDL and DML for Instance-Level Synchronization

        Select the SQL operations for incremental migration at the instance level. For information about the supported operations, see Supported SQL operations for incremental migration.

        Note

        To select SQL operations for incremental migration at the database or table level, right-click a migration object in the Selected Objects box and select the SQL operations that you want to migrate in the dialog box that appears.

        Case Policy for Destination Object Names

        You can configure the case sensitivity policy for the names of databases, tables, and columns in the destination instance. By default, DTS default policy is selected. You can also select a policy to be consistent with the source or destination database. For more information, see Case sensitivity policy for destination object names.

        Storage Engine Type

        Select a storage engine for the destination tables based on your business requirements. The default value is Beam.

        Note

        This parameter is available only if the destination AnalyticDB for PostgreSQL instance has a kernel version of v7.0.6.6 or later and you selected Migration Types for the Schema Migration parameter.

        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

        The granularity for selecting migration objects is schema, table, and column. If you select only tables or columns as migration objects, other objects such as views, triggers, and stored procedures are not migrated to the destination database.

        Selected Objects
        Note

        • If you use the object name mapping feature, the migration of dependent objects may fail.

        • To specify WHERE conditions to filter data, right-click a table to be migrated in the Selected Objects box and specify the filter conditions 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 a migration object in the Selected Objects box and select the desired SQL operations in the dialog box that appears.

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

        Parameter

        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.

        Copy temporary tables created by online DDL tools from the source table to the destination database

        If you use Data Management (DMS) or gh-ost to perform online DDL changes in the source database, you can choose whether to migrate the data from the temporary tables generated by the online DDL changes.

        Important

        • DTS tasks do not support using tools such as pt-online-schema-change to perform online DDL changes. Otherwise, the DTS task fails.

        • The processing methods for each phase are as follows: The Schema Migration and Full Data Migration phases do not allow DDL operations that change the database or table structure. Therefore, they are not controlled by the online DDL policy.

          • Schema Migration: Not controlled by the online DDL policy. Related temporary tables are created.

          • Full Data Migration: Not controlled by the online DDL policy. The migration of temporary tables is not included in the full migration objects. All tables whose names match the regular expression (^_(.+)_(?:gho|new)$ or ^_(.+)_(?:ghc|del|old)$) are filtered out.

          • Incremental Data Migration: Controlled by the online DDL policy.

            • Yes: Migrates data changes from temporary tables (for example, _table_name_gho) generated by online DDL operations.

            • No, Adapt to DMS Online DDL and No, Adapt to gh-ost: Filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules.

        • Yes: Migrates the data from the temporary tables generated by online DDL changes.

          Note

          If online DDL changes generate a large amount of data in temporary tables, it may cause task latency.

        • No, Adapt to DMS Online DDL: Does not migrate the data from the temporary tables generated by online DDL changes. It only migrates the original DDL statements executed using Data Management (DMS).

          Note

          This option causes tables in the destination database to be locked.

        • No, Adapt to gh-ost: Does not migrate the data from the temporary tables generated by online DDL changes. It supports custom filtering rules. DTS filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules. You can modify the default regular expressions used to match shadow and useless tables as needed:

          • Shadow table: ^_(.+)_(?:gho|new)$

          • Useless table: ^_(.+)_(?:ghc|del|old)$

          Note

          This option causes tables in the destination database to be locked.

        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 Full Data Migration

        During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database.

        Note

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

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

        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.

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

        Choose whether DTS writes heartbeat SQL information to the source database while the instance is running.

        • Yes: Does not write heartbeat SQL information to the source database. The DTS instance may display latency.

        • No: Writes heartbeat SQL information to the source database. This may interfere with source database operations like physical backups and cloning.

        Environment Tag

        You can select environment tags to identify the instance. In this example, you do not need to select a tag.

        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.

      3. After you configure the parameters, click Next: Configure Database and Table Fields at the bottom of the page to set the primary key and distribution key columns for the tables to be migrated in the destination AnalyticDB for PostgreSQL instance.

        Note

        This page appears only if Schema Migration is selected for Migration Types. For more information about primary key and distribution key columns, see Manage tables and Define table distribution.

    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 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.