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Migrate RDS for MySQL to Tablestore

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Data Transmission Service (DTS) allows you to migrate data from an ApsaraDB RDS for MySQL instance to a Tablestore instance.

Prerequisites

Considerations

Type

Description

Source database limitations

  • Tables to be synchronized must have a primary key or a unique constraint on unique columns. Otherwise, data duplication can occur in the destination database.

  • If you are migrating at the table level and need to edit the objects, for example, by mapping table or 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, we recommend splitting the tables across multiple data migration tasks or configuring a task to migrate the entire database.

  • If you need incremental migration, enable binary logging:

    • Set binlog_format to ROW and binlog_row_image to FULL. Otherwise, the precheck fails and the task cannot start.

      Important

      If your self-managed MySQL source is a dual-master cluster—where each instance acts as both master and slave—enable the log_slave_updates parameter. This ensures DTS can read all binary logs.

    • For RDS for MySQL instances, retain local binary logs for at least three days (seven days recommended). For self-managed MySQL databases, retain local binary logs for at least seven days. If DTS cannot access binary logs, the task fails. In extreme cases, data inconsistency or data loss may occur. Issues caused by binary log retention periods shorter than DTS requires are not covered under the DTS SLA.

      Note

      To set the retention period for local binary logs on an RDS for MySQL instance, see Automatically delete local logs.

  • 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 you need incremental migration, RDS for MySQL instances that do not record transaction logs—such as RDS for MySQL 5.6 read-only instances—are not supported as sources.

  • DTS does not migrate data generated by changes that do not write to binary logs. Examples include data restored from physical backups or created by cascade operations.

    Note

    If this occurs, re-run full migration after your business allows it.

  • If your source MySQL database is version 8.0.23 or later and contains invisible hidden columns, DTS cannot read those columns. This may cause data loss.

    Note

    Run ALTER TABLE <table_name> ALTER COLUMN <column_name> SET VISIBLE; to make the hidden column visible. For more information, see Invisible Columns.

Other limitations

  • Do not use tools such as pt-online-schema-change to perform online DDL operations on the migration objects in the source database. Otherwise, the migration task will fail.

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

  • Before you migrate data, evaluate the performance of the source and destination databases. We recommend migrating data during off-peak hours. This is because during full data migration, DTS consumes read and write resources of the source and destination databases, which may increase database loads.

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

  • DTS attempts to resume a failed data migration task within seven days. Therefore, before you switch workloads to the destination instance, you must end or release the data migration task. Alternatively, 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 being automatically resumed and overwriting data in the destination instance with data from the source database.

  • Make sure that the number of tables to be migrated meets the limit of the Tablestore instance (no more than 64). If your business requires more than this limit, request a higher limit for the destination Tablestore instance.

  • Make sure that the names of tables and columns to be migrated follow the naming conventions of Tablestore:

    • A table or column name can contain uppercase letters, lowercase letters, digits, and underscores (_). It must start with a letter or an underscore (_).

    • A table or column name must be 1 to 255 characters in length.

  • If your RDS for MySQL instance has Always-Encrypted enabled, full migration is not supported.

    Note

    RDS for MySQL instances with Transparent Data Encryption (TDE) enabled support schema migration, full migration, and incremental migration.

  • 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.

Special cases

  • For self-managed MySQL sources:

    • A master–standby switchover on the source database causes the migration task to fail.

    • DTS calculates latency by comparing the timestamp of the last record migrated to the destination database with the current time. If no DML operations run on the source for a long time, latency reporting becomes inaccurate. If latency appears too high, run a DML operation on the source to update the latency value.

      Note

      If you select full-database migration, create a heartbeat table. Update or write to it every second.

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

    • If your source is Amazon Aurora MySQL or another clustered MySQL instance, ensure the domain name or IP address configured for the task—and its DNS resolution—always points to a read–write (RW) node. Otherwise, the migration task may fail.

  • For RDS for MySQL sources:

    • If you need incremental migration, RDS for MySQL instances that do not record transaction logs—such as RDS for MySQL 5.6 read-only instances—are not supported as sources.

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

Billing

Migration type

Task configuration fee

Internet traffic fee

Schema migration and full data migration

Free.

Fees are charged for migrating data from Alibaba Cloud over the Internet. For more information, see Billing overview.

Incremental data migration

Charged. For details, see Billing overview.

Migration types

  • Schema migration

    DTS migrates the schemas of migration objects from the source database to the destination database.

  • Full data migration

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

  • Incremental data migration

    After a full data migration, DTS synchronizes incremental data updates from the source database to the destination database. This lets you complete the migration with minimal downtime for your self-managed applications.

Supported SQL operations for incremental migration

Operation type

SQL statement

DML

INSERT, UPDATE, and DELETE

Database account permissions

Database

Schema migration

Full data migration

Incremental data migration

ApsaraDB RDS for MySQL

SELECT permission

SELECT permission

The SELECT permission on the objects to be migrated, and the REPLICATION SLAVE and REPLICATION CLIENT permissions. DTS automatically grants these permissions to the database account.

To create a database account and grant permissions for an ApsaraDB RDS for MySQL instance, see Create an account and Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance.

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.

    Category

    Parameter

    Description

    N/A

    Task Name

    DTS automatically generates a task name. We recommend specifying a descriptive name, which does not need to be unique, for easier task identification.

    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 MySQL.

    Connection Type

    Select Alibaba Cloud Instance.

    Instance Region

    Select the region where the source ApsaraDB RDS for MySQL instance is located.

    Cross-account

    In this example, data is migrated within the same Alibaba Cloud account. Select No.

    RDS Instance ID

    Select the ID of the source ApsaraDB RDS for MySQL instance.

    Database Account

    Enter the database account for the source ApsaraDB RDS for MySQL instance. For more information about the required permissions, see Permissions required for database accounts.

    Database Password

    Enter the password for the database account.

    Connection Method

    Select Non-encrypted or SSL-encrypted based on your database requirements. If you set this parameter to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Quickly enable SSL encryption using a cloud certificate.

    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 Tablestore.

    Connection Type

    Select Alibaba Cloud Instance.

    Instance Region

    Select the region where the destination Tablestore instance is located.

    Instance ID

    Select the ID of the destination Tablestore instance.

    AccessKey ID of Alibaba Cloud Account

    Enter the AccessKey ID of your Alibaba Cloud account. For information about how to obtain an AccessKey ID, see Create an AccessKey pair.

    AccessKey Secret of Alibaba Cloud Account

    Enter the AccessKey Secret of your Alibaba Cloud account. For information about how to obtain an AccessKey Secret, see Create an AccessKey pair.

  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 of Conflicting 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.

      Operation Types

      Select the types of operations to synchronize based on your business requirements. By default, all operation types are selected.

      Processing Policy of Dirty Data

      Select the policy for handling data write errors. Valid values:

      • Skip

      • Block

      Data Write Mode

      Select the data writing mode. Valid values:

      • Update Row: Uses PutRowChange to perform row-level updates.

      • Overwrite Row: Uses UpdateRowChange to perform row-level overwrites.

      Batch Write Mode

      The API operation for batch writing. Valid values:

      • BulkImportRequest: Writes data offline.

      • BatchWriteRowRequest: Writes data in batches.

      We recommend that you select BulkImportRequest for higher read and write efficiency and lower costs for the Tablestore instance.

      More

      Configure the following parameters as needed:

      • Queue Size: The queue length for the data writing process of the Tablestore instance.

      • Thread Quantity: The number of callback handling threads for the data writing process of the Tablestore instance.

      • Concurrency: The maximum number of concurrent requests for the Tablestore instance.

      • Buckets: The number of concurrent buckets for sequential writing of incremental data. A larger value can improve concurrent writing capabilities.

        Note

        The value must be less than or equal to the concurrency.

      Capitalization of Object Names in Destination Instance

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

      Source Objects

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

      Note

      • You can select databases or tables as migration objects. If you select only tables, other objects such as views, triggers, and stored procedures are not migrated to the destination database.

      • You can migrate tables only from a single database. You can select either a single database or multiple tables from the same database.

      Selected Objects
      Note

      • Hover over a table you want to synchronize and click the Edit icon next to its name to set the data type for each column of the table in the Tablestore instance.

      • Only table names support the mapping feature. If you use the object name mapping feature, other objects that depend on the mapped object may fail to migrate.

      • To set a WHERE clause to filter data, right-click the table to migrate in the Selected Objects section and set the filter condition in the dialog box. For instructions, see Set filter conditions.

    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 based on your requirements. This parameter is optional for this example.

      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

      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 contact. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

    3. After completing the preceding configurations, click Next: Configure Database and Table Fields to configure the primary key columns for the tables to be synchronized in the Tablestore instance.

  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.

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