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    Data Transmission Service:Synchronize PolarDB for MySQL to AnalyticDB for MySQL 3.0

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    Data Transmission Service:Synchronize PolarDB for MySQL to AnalyticDB for MySQL 3.0

    Last Updated:Apr 15, 2026

    Use DTS to synchronize data from a PolarDB for MySQL cluster to an AnalyticDB for MySQL 3.0 cluster to quickly build internal business intelligence (BI), interactive query, and real-time reporting systems.

    Prerequisites

    Limitations

    Note

    • During schema synchronization, DTS does not synchronize foreign keys from the source database to the destination database.

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

    Type

    Description

    Source database limits

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

    • If you synchronize data at the table level and need to edit the tables, such as mapping column names, a single data synchronization task supports a maximum of 1,000 tables. If you exceed this limit, an error is reported when you submit the task. In this case, split the tables into multiple synchronization tasks or configure a task to synchronize the entire database.

    • Binary logs:

      • You must enable binary logging and set the loose_polar_log_bin parameter to ON. Otherwise, an error is reported during the precheck and the DTS instance fails to start. For more information about how to enable binary logging and modify parameters, see Enable binary logging and Set cluster and node parameters.

        Note

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

      • The binary logs of the PolarDB for MySQL cluster must be retained for at least 3 days. We recommend that you retain them for 7 days. Otherwise, the DTS task may fail because DTS cannot obtain the binary logs. In extreme cases, this may cause data inconsistency or data loss. Issues caused by a binary log retention period shorter than the required period 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 synchronization, do not perform DDL operations to modify primary keys or add comments to tables, such as ALTER TABLE table_name COMMENT='Table comment';. Otherwise, the DDL operations fail to be executed during data synchronization.

    • Do not run DDL operations that change database or table schemas during schema synchronization or full synchronization. Otherwise, the synchronization task fails.

      Note

      During full synchronization, DTS queries the source database. This creates metadata locks that may block DDL operations on the source database.

    Other limits

    • Synchronization of prefix indexes is not supported. If the source database has prefix indexes, the data synchronization may fail.

    • Primary/secondary failover of the database instance is not supported during initial full data synchronization. If a failover occurs, reconfigure the synchronization task promptly.

    • If your source database uses online DDL operations in temporary table mode—including but not limited to multi-table merge scenarios—or adds function-based indexes to unique key columns, data loss or task failure may occur in the destination database.

    • If a primary key or unique key conflict occurs while the task is running:

      • If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database:

        • During full data synchronization, DTS retains the destination record and skips the source record.

        • During incremental synchronization, DTS overwrites the destination record with the source record.

      • If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.

    • The destination database must contain a custom primary key. Or, in the Configurations for Databases, Tables, and Columns step, configure a Primary Key Column. Otherwise, synchronization may fail.

    • You cannot synchronize data from a read-only node of the source PolarDB for MySQL cluster.

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

    • You cannot synchronize OSS foreign tables from the source PolarDB for MySQL cluster.

    • Due to the limits of AnalyticDB for MySQL, if the disk space usage of a node in the AnalyticDB for MySQL cluster exceeds 80%, the DTS task becomes abnormal and latency occurs. Estimate the required space based on the objects to be synchronized in advance to ensure that the destination cluster has sufficient storage space.

    • If the destination AnalyticDB for MySQL 3.0 cluster is backing up while the DTS task runs, the task fails.

    • Before you synchronize data, evaluate the performance of the source and destination databases. We recommend that you synchronize data during off-peak hours. Otherwise, initial full data synchronization consumes read and write resources on the source and destination databases, which may increase the database load.

    • Initial full data synchronization runs concurrent INSERT operations, which causes fragmentation in the destination database tables. As a result, the tablespace of the destination instance is larger than that of the source instance after initial full data synchronization is complete.

    • For table-level data synchronization, do not use tools such as pt-online-schema-change to perform online DDL operations on the synchronization objects in the source database. Otherwise, the synchronization fails.

    • For table-level data synchronization, if no data other than the data from DTS is written to the destination database, you can use Data Management (DMS) to perform online DDL operations. For more information, see Change schemas without locking tables.

    • During DTS synchronization, do not write data other than the data from DTS to the destination database. Otherwise, data inconsistency between the source and destination databases may occur. For example, if you use DMS to perform online DDL operations while other data is being written to the destination database, data may be lost in the destination database.

    • If a DDL operation fails to be written to the destination database, the DTS task continues to run. You need to check the task logs for the failed DDL operation. For more information about how to view task logs, see View task logs.

    • 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 notes

    DTS periodically runs the CREATE DATABASE IF NOT EXISTS `test` command on the source database to advance the binary log offset.

    Billing

    Synchronization type

    Pricing

    Schema synchronization and full data synchronization

    Free of charge.

    Incremental data synchronization

    Charged. For more information, see Billing overview.

    One-way synchronization topologies

    • One-to-one

    • One-to-many

    • Many-to-one

    Supported SQL operations

    Operation type

    SQL statement

    DML

    INSERT, UPDATE, and DELETE

    Note

    When you write data to AnalyticDB for MySQL, it automatically converts UPDATE statements to REPLACE INTO statements. If you update a primary key, the system converts the UPDATE statement into DELETE and INSERT statements.

    DDL

    CREATE TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE, ADD COLUMN, MODIFY COLUMN, and DROP COLUMN

    Important

    The RENAME TABLE operation may cause data inconsistency. For example, if the synchronization object is a single table and you rename it on the source instance during synchronization, the data of that table is not synchronized to the destination database. To avoid this issue, you can configure the task to synchronize the entire database that contains the table. Make sure that the database to which the table belongs both before and after the RENAME TABLE operation is included in the synchronization objects.
    Warning

    If you change the data type of a field in a source table during data synchronization, the data synchronization task reports an error and stops. To manually fix the issue, follow these steps:

    1. In this example, a data synchronization task has failed because the data type of a field was changed in a source table (e.g., customer) during synchronization to an AnalyticDB for MySQL database.

    2. In your AnalyticDB for MySQL 3.0 cluster, create a new table (for example, customer_new) with the same schema as the customer table.

    3. Run the INSERT INTO SELECT statement to copy data from the customer table to the customer_new table. This ensures the data in the two tables is consistent.

    4. Rename or delete the customer table. Then, rename the customer_new table to customer.

    5. In the DTS console, restart the data synchronization task.

    Procedure

    1. Go to the data synchronization task list page in the destination region. You can do this in one of two ways.

      DTS console

      1. Log on to the DTS console.

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

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

      DMS console

      Note

      The actual steps may vary depending 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 DMS console.

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

      3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.

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

    3. Configure the source and destination databases.

      Warning

      After you select the source and destination instances, review the Limits at the top of the page. Otherwise, the task may fail or data inconsistency may occur.

      Category

      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

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

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

      Database Type

      Select PolarDB for MySQL.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region of the source PolarDB for MySQL cluster.

      PolarDB Cluster ID

      Select the instance ID of the source PolarDB for MySQL cluster.

      Database Account

      Enter the database account of the source PolarDB for MySQL cluster. This account must have read permissions on the objects to be synchronized.

      Database Password

      Enter the password for the specified database account.

      Encryption

      Select a method based on your requirements. For more information about SSL encryption, see Configure SSL encryption.

      Destination Database

      Select Existing Connection

      • Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.

        Note

        In the DMS console, this configuration item is Select a DMS database instance.

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

      Database Type

      Select AnalyticDB for MySQL 3.0.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region of the target AnalyticDB for MySQL 3.0 cluster.

      Instance ID

      Select the instance ID of the target AnalyticDB for MySQL 3.0 cluster.

      Database Account

      Enter the database account of the target AnalyticDB for MySQL 3.0 cluster. This account must have read and write permissions.

      Database Password

      Enter the password for the specified 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 blocks of the DTS service are added to the security settings of the source and destination databases, either automatically or manually, to allow access from DTS servers. For more information, see Add the IP address whitelist of DTS servers.

    5. Configure the task objects.

      1. On the Configure Objects page, specify the objects to synchronize.

        Parameter

        Description

        Synchronization Types

        DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.

        Note

        If you select Full Data Synchronization, the schemas and data of the tables that are created by using the CREATE TABLE statement can be synchronized to the destination database.

        DDL and DML Operations to Be Synchronized

        Select the DDL or DML operations to synchronize at the instance level. For information about supported operations, see Supported SQL operations.

        Note

        To select SQL operations to synchronize at the database or table level, right-click an object in the Selected Objects list and select the desired SQL operations from the shortcut menu.

        Merge Tables

        • Select Yes: In online transactional processing (TP) scenarios, sharding is often used to improve the response speed of business tables. In online analytical processing (OLAP) scenarios, a single table in the destination database can store large volumes of data, which simplifies single-table queries. In such scenarios, you can use the DTS table merging feature to synchronize multiple tables with the same schema (sharded tables) from the source database to a single table in the destination database. For details on this operation, see Enable table merging.

          Note

          • After you select multiple tables from the source database, you must use the object name mapping feature to change their names to the same table name in the destination database. For more information about the object name mapping feature, see Database Table Column Name Mapping.

          • DTS adds a __dts_data_source column of the TEXT type to the destination table to store the data source. The column value is written in the DTS instance ID:database name:schema name:table name format to distinguish the source of the table, for example, dts********:dtstestdata:testschema:customer1.

          • The table merging feature applies at the task level, not the table level. To merge only some tables, you must create a separate data synchronization task for them.

          Warning

          Do not perform DDL operations that change the database or table schema in the source database. Otherwise, data inconsistency or task failure may occur.

        • No: This is the default option.

        Processing Mode of Conflicting Tables

        • Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful.

          Note

          If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Database Table 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 put your business at risk. For example:

          • If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database:

            • During full data synchronization, DTS retains the destination record and skips the source record.

            • During incremental synchronization, DTS overwrites the destination record with the source record.

          • If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.

        Capitalization of Object Names in Destination Instance

        Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.

        Source Objects

        In the Source Objects box, click the objects, and then click 向右 to move them to the Selected Objects box.

        Note

        • You can select databases, tables, and columns as synchronization objects. If you select tables or columns as synchronization objects, DTS does not synchronize other objects such as views, triggers, and stored procedures to the destination database.

        • If you select an entire database as the synchronization object, the following default rule applies:

          • If a table to be synchronized in the source database has a primary key that contains one or more columns, DTS uses the primary key columns as the distribution key.

        Selected Objects

        • To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name.

        • To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk.

        Note

        • To select SQL operations to synchronize at the database or table level, right-click the object in the Selected Objects list and select the desired SQL operations in the dialog box that appears. For a list of supported operations, see Supported SQL operations.

        • To filter data by using a WHERE clause, right-click the table in the Selected Objects list and specify the filter condition in the dialog box that appears. For instructions, see Configure data filtering.

      2. Click Next: Advanced Settings.

        Parameter

        Description

        Dedicated Cluster for Task Scheduling

        By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.

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

        DDL operations cannot be synchronized. Select No, Adapt To DMS Online DDL or No, Adapt To Gh-ost. If DDL synchronization is supported for this scenario in the future, you can choose whether to synchronize the temporary tables that are generated when you use Data Management (DMS) or gh-ost for online DDL changes.

        • Yes: Synchronizes data in temporary tables created by online DDL changes.

          Note

          If the data of temporary tables generated by online DDL changes is too large, it may cause synchronization latency.

        • No, Adapt to DMS Online DDL: Does not synchronize data from temporary tables generated by online DDL changes. Only the original DDL statements executed in Data Management (DMS) are synchronized.

          Note

          This option causes locked tables in the destination database.

        • Do not adapt to gh-ost: This option does not synchronize data from temporary tables generated by online DDL changes. Instead, it only synchronizes the original DDL statements executed by gh-ost. You can use default or custom regular expressions for gh-ost shadow and junk tables.

          Note

          This option causes locked tables in the destination database.

        Retry Time for Failed Connections

        If the connection to the source or destination database fails after the synchronization task starts, 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 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails.

        Note

        • If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances.

        • DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.

        Retry Time for Other Issues

        If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails.

        Important

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

        Enable Throttling for Full Data Synchronization

        During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s).

        Note

        Enable Throttling for Incremental Data Synchronization

        You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).

        Environment Tag

        You can select an environment tag to identify the instance based on your requirements. This parameter is optional.

        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.

        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

        Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts.

      3. Click Data Verification to configure a data verification task.

        To use the data verification feature, see Configure data verification.

      4. Optional: After you complete the configuration, click Next: Configure Database and Table Fields to set the Type, Primary Key Column, Distribution Key, and partition key information (Partition Key, Partitioning Rules, and Partition Lifecycle) for the tables to sync in the destination database.

        Note

        • This step is available only if you select the Schema Synchronization checkbox for Synchronization Types during task object configuration. You can set Definition Status to All to make modifications.

        • You can use the Primary Key Column to specify a composite primary key that consists of multiple columns. You must then select one or more columns from the Primary Key Column to serve as the Distribution Key and Partition Key. For more information, see CREATE TABLE.

    6. Save the task and perform a precheck.

      • To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.

      • If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

      Note

      • Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.

      • If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.

      • If the precheck generates warnings:

        • For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.

        • For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.

    7. Purchase the instance.

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

      2. On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

        Category

        Parameter

        Description

        New Instance Class

        Billing Method

        • Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks.

        • Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.

        Resource Group Settings

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

        Instance Class

        DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.

        Subscription Duration

        In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years.

        Note

        This option appears only when the billing method is Subscription.

      3. Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.

      4. Click Buy and Start, and then click OK in the OK dialog box.

        You can monitor the task progress on the data synchronization page.