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    Data Transmission Service:Migrate from PolarDB-X 1.0 to Elasticsearch

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    Data Transmission Service:Migrate from PolarDB-X 1.0 to Elasticsearch

    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 an Elasticsearch cluster.

    Prerequisites

    • You have 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 a destination Elasticsearch cluster. For more information, see Create an Alibaba Cloud Elasticsearch cluster.

    • The available storage space on the destination Elasticsearch cluster must exceed the total data size of the source PolarDB-X 1.0 instance.

    Notes

    Type

    Description

    Source database limitations

    • Tables to be migrated must have a PRIMARY KEY or a UNIQUE constraint, and the fields in the key or constraint must be unique. Otherwise, this may cause duplicate data in the destination database.

    • 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 data migration, the source database must meet the following binary log requirements:

      • Enable the binary log feature, and set the binlog_row_image parameter to full. Otherwise, the precheck fails and the data migration task cannot start.

      • For incremental data migration tasks, DTS requires that the binary logs of the source database be retained for at least 24 hours. For tasks that include both full data migration and incremental data migration, the binary logs must be retained for at least 7 days. You can change the retention period to 24 hours after the full data migration is complete. If the binary logs are not retained for the required period, DTS may fail to obtain them, which can cause task failures or even data inconsistency and loss. The DTS SLA does not cover issues caused by an insufficient binary log retention period.

    • Data migration from PolarDB-X 1.0 read-only instances is not supported.

    • Operational restrictions on the source database:

      • During data migration, do not perform operations such as scaling out, scaling in, migrating hot-spot tables, changing the sharding key, or executing DDL statements. 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 the partition key is changed in the source database and the primary key in the target table does not include the source partition key, data loss may occur in the target database.

        • Reason: A PolarDB-X 1.0 instance has multiple RDS for MySQL instances attached to it. DTS creates a separate migration link for each RDS for MySQL instance. A change to a partition key causes data to be deleted from one RDS for MySQL instance and inserted into another. Because the links execute independently, the execution order of the DELETE and INSERT operations is not guaranteed. If the primary key of the target database does not include the partition key, a DELETE operation that executes later may accidentally delete the newly inserted data.

        • Recommendation: To prevent data loss caused by out-of-order operations, ensure that the primary key of the target table includes the partition key column from 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 switch the network type of the PolarDB-X 1.0 instance during migration, update the migration link's network connection information after the switch is complete.

      • If you perform only full data migration, do not write new data to the source database during the migration. Otherwise, data will become inconsistent 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

    • DTS does not support migrating indexes, partitions, views, procedures, functions, triggers, or foreign keys.

    • To add a column to a table during migration, first modify the mapping of the corresponding table in the Elasticsearch instance, then execute the required DDL operation on the source database, and finally pause and restart the migration task.

    • Do not migrate data to a destination index that contains parent-child relationships or a Join field type mapping. Otherwise, this may cause task exceptions or query failures in the destination database.

    • 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.

    • DTS supports the Timestamp type for time fields. When the time field in the source database is 0, DTS automatically converts the corresponding time field in the target database to null.

    • Before you migrate data, evaluate the performance of the source and target databases. Migrate data during off-peak hours. During a full migration, DTS consumes read and write resources on both the source and target databases, which can increase the database load.

    • DTS attempts to resume a failed migration task within seven days. Therefore, before you switch your workloads to the target instance, you must stop or release the task, or revoke write permissions from the account that DTS uses to access the target instance by using the revoke command. This prevents the task from automatically resuming and overwriting data in the target instance with data from the source.

    • Development and test specifications of Elasticsearch instances are not supported.

    • 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

    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 the schema definitions of the migration objects from the source database to the destination database.

    • Full migration

      DTS migrates all historical data of the specified migration objects from the source database to the destination database.

    • Incremental migration

      After a full migration is complete, DTS migrates incremental data updates from the source database to the destination database. Incremental migration lets you smoothly migrate data without interrupting your self-managed applications.

    SQL operations for incremental migration

    Type

    SQL statement

    DML

    INSERT, UPDATE, and DELETE

    Note

    Using an UPDATE statement to remove a column is not a supported operation.

    Database account permissions

    Database

    Schema migration

    Full migration

    Incremental migration

    PolarDB-X instance

    SELECT

    SELECT

    Read and write permissions on the objects to migrate.

    Note

    For more information, see Manage accounts.

    Elasticsearch instance

    The database account must have read and write permissions. This account is typically elastic.

    Data type mapping

    • A source database and an Elasticsearch instance support different data types that cannot always be mapped directly. During structure initialization, DTS maps data types based on those supported by the target Elasticsearch instance. For more information, see Data type mapping for structure initialization.

      Note

      During the DTS schema migration process, DTS does not set the dynamic parameter in mapping. The behavior of this parameter depends on the settings of your Elasticsearch instance. If your source data is of the JSON type, you must ensure that for a specific key, its corresponding values have the same data type across all rows in a table. Otherwise, DTS may encounter synchronization issues. For more information, see dynamic.

    • The mapping between Elasticsearch and a relational database varies by Elasticsearch version.

      Important

      Starting with Elasticsearch 7.0, an index no longer supports multiple types, and types were completely removed in Elasticsearch 8.0. By default, when you configure a synchronization or migration task, DTS maps a table from a relational database to an index in Elasticsearch. You can change this mapping when you configure the objects to synchronize or migrate.

      Elasticsearch 7.0 and later

      Elasticsearch

      Relational database

      index

      table

      document

      row

      field

      column

      mapping

      schema

      Versions before Elasticsearch 7.0

      Elasticsearch

      Relational database

      index

      database

      type

      table

      document

      row

      field

      column

      mapping

      schema

    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-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 topic uses a data migration task within the same Alibaba Cloud account as an example. Select No.

      RDS 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 information about the required permissions, see Permissions required for database accounts.

      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 Elasticsearch.

      Connection Type

      Select Alibaba Cloud Instance.

      Instance Region

      Select the region where the destination Elasticsearch instance is located.

      Type

      Select Cluster or Serverless based on your business requirements.

      Instance ID

      Select the ID of the destination Elasticsearch instance.

      Database Account

      Enter the account for your Elasticsearch instance. This is the Username that you specified when you created the instance. The default account is elastic.

      Database Password

      Enter the password for the database account.

      Encryption

      Select HTTP or HTTPS as needed.

    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

        Synchronization Type

        • 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: Checks whether tables with the same names exist in the destination database. If no tables with the same names exist, the precheck is passed. If tables with the same names exist, an error is reported during the precheck, and the data migration task does not start.

          Note

          If a table in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the table in the destination database. For more information, see Object name mapping.

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

          Warning

          Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example:

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

            • During full migration, DTS keeps the record in the destination database. The record from the source database is not migrated.

            • During incremental migration, DTS does not keep the record in the destination database. The record from the source database overwrites the record in the destination database.

          • If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.

        Index Name

        • If you select Table Name, the index created in the destination Elasticsearch instance uses the same name as the source table.

        • If you select Database Name_Table Name, the index created in the destination Elasticsearch instance is named in the database_name_table_name format.

        Note

        The index name mapping configuration takes effect for all tables.

        Case Policy for Destination Object Names

        You can configure the case sensitivity of database, table, and column names for the migrated objects in the destination instance. By default, DTS default policy is selected. You can also choose to align with the default policies of the source or destination database. For more information, see Case sensitivity of object names in the destination database.

        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

        Select objects to migrate at the table level. If you select an entire database, any changes to add or delete tables in that database will not be migrated to the destination.

        Selected Objects
        Note

        • Only underscores (_) are supported as special characters in index and type names.

        • If you use the object name mapping feature, other objects that depend on the renamed object may fail to be migrated.

        • To filter data by using WHERE conditions, right-click a table 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 the SQL operations to be migrated 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.

        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.

        Environment Tag

        You can select an environment tag to identify the instance. For this example, no tag is needed.

        Shard Configuration

        Set the number of primary shards and replica shards for the index based on the maximum shard configuration of the indexes in the destination Elasticsearch cluster.

        String Index

        The method used to index strings in the destination Elasticsearch instance.

        • analyzed: The string is analyzed and then indexed. You also need to select a specific analyzer. For more information about analyzer types and their functions, see Analyzers.

        • not analyzed: The string is indexed with its original value without analysis.

        • no: The string is not indexed.

        Time Zone

        When DTS migrates time-related data types such as DATETIME and TIMESTAMP to the destination Elasticsearch instance, you can select a time zone for the data.

        Note

        If this type of data in the destination instance does not require a time zone, you must set the document type (type) for this data type in the destination instance in advance.

        DOCID

        By default, the DOCID is the primary key of the table. If the table does not have a primary key, the DOCID is an ID column automatically generated by Elasticsearch.

        Configure ETL

        Based on your business needs, select whether to configure the ETL feature to process data.

        • Yes: Configures the ETL feature. You must also enter data processing statements in the text box.

        • No: Does not configure the ETL feature.

        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 complete the settings, click Next: Configure Database and Table Fields. On the next page, set the _routing policy and _id value for the tables to be migrated to the destination Elasticsearch cluster.

        Type

        Description

        Set _routing

        The _routing feature allows you to route documents to a specific shard in the destination Elasticsearch instance. For more information, see _routing.

        • If you select Yes, you can specify custom columns for routing.

        • If you select No, the _id value is used for routing.

        Note

        If the destination Elasticsearch instance is version 7.x, you must select No.

        _routing Column

        Select the column to use for routing.

        Note

        This parameter is required only if you select Yes for Set _routing.

        Value of _id

        Select the column to use as the document ID.

    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.