Migrate PolarDB-X 1.0 to Message Queue for Apache Kafka

Prerequisites

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

  Note

  The storage type of the source PolarDB-X 1.0 instance must be RDS for MySQL, including custom and separately purchased RDS instances. PolarDB for MySQL is not supported.

• You have created a destination ApsaraMQ for Kafka instance and a topic in that instance to receive the migrated data. For more information about ApsaraMQ for Kafka, see Overview.

  Note

  See Migration solution overview for the versions supported by the source and destination instances.

• The destination ApsaraMQ for Kafka instance must have more available storage space than the source PolarDB-X 1.0 instance's storage usage.

Precautions

Billing

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.

Supported SQL operations for incremental migration

Database account permissions

Data type mapping

For details, see Data Type Mappings for Initial Schema Synchronization.

Procedure

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

   From the DTS console

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

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

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

   From the DMS console

   Note

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

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

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

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

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

3. Configure the source and destination databases.

   Warning

   After selecting the source and destination instances, carefully read the Limits section at the top of the page. This helps ensure that the data migration task can be successfully created and run.

   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	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 example shows data migration within the same Alibaba Cloud account. Select No.
   	Instance ID	Select the ID of the source PolarDB-X 1.0 instance.
   	Database Account	Enter the database account for the source PolarDB-X 1.0 instance. Ensure the account has the required permissions.
   	Database Password	Enter the password for the database account.
   Destination Database	Select Existing Connection	To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured. Note In the DMS console, this parameter is named Select a DMS database instance.. If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.
   	Database Type	Select Kafka.
   	Connection Type	Select Express Connect, VPN Gateway, or Smart Access Gateway. Note In this case, the Message Queue for Apache Kafka instance is treated as a self-managed Kafka instance for this data migration task.
   	Instance Region	Select the region where the destination Kafka project is located.
   	Connected VPC	Select the Basic Information of the destination Kafka instance. You can find the VPC ID on the Basic Information page of the Kafka instance.
   	Domain Name or IP	Enter an IP address from the Default Endpoint of the Kafka instance. Note You can find the IP address of the Default Endpoint on the Basic Information page of the Kafka instance.
   	Port	The service port of the Kafka instance. The default value is 9092.
   	Database Account	Enter the database account and password for the destination Kafka instance. Note These parameters are required only for Message Queue for Apache Kafka instances with Access Control List (ACL) enabled. For more information about how to enable ACL, see SASL user authorization.
   	Database Password
   	Kafka Version	Select the version of your Kafka instance.
   	Encryption	Based on your business and security requirements, select Non-encrypted or SCRAM-SHA-256.
   	Topic	From the drop-down list, select the topic to receive the migrated data.
   	Use Kafka Schema Registry	Kafka Schema Registry provides a serving layer for your metadata. It offers a RESTful interface for storing and retrieving Avro schemas. No: Does not use Kafka Schema Registry. Yes: Uses Kafka Schema Registry. You must enter the URL or IP address for your Avro schema as registered in the Kafka Schema Registry.

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	Select the migration types based on your requirements and the types supported by each engine. 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.
      Data Format in Kafka	Select the data format for storing data in the destination Kafka instance. If you select DTS Avro, you must parse the data based on the DTS Avro schema definition. For more information, see DTS Avro Schema Definition and DTS Avro Deserialization Example. If you select Canal Json, see Canal JSON format for parameter descriptions and examples. Note PolarDB-X 1.0 does not support Canal Json. You must select DTS Avro.
      Kafka Data Compression Format	Select a compression format for Kafka messages based on your requirements. LZ4 (default): low compression ratio, high compression speed. GZIP: high compression ratio, low compression speed. Note High CPU consumption. Snappy: medium compression ratio, medium compression speed.
      Policy for Shipping Data to Kafka Partitions	This feature is not currently supported.
      Message acknowledgement mechanism	Select a message acknowledgment mechanism based on your business requirements.
      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	In the Source Objects box, click the objects to migrate, and then click to move them to the Selected Objects box. Note Select tables as the migration objects. If you select an entire database, changes such as adding or deleting tables in that database are not migrated to the destination database.
      Selected Objects	No additional configuration is required for this example. You can use the mapping feature to set the topic name, number of partitions, and partition key for the source table in the destination Kafka instance. For more information, see Map object names. Note If you use the object name mapping feature, other objects that depend on the mapped object may fail to be migrated. To select the SQL operations for incremental migration, right-click an 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	You do not need to select a dedicated cluster for this example. For more information about dedicated clusters, see What is a DTS dedicated cluster?.
      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 is not required for this example.
      Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables 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.

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.

Mapping information

1. In the Selected Objects area, hover over the destination topic name at the table level.

2. Click Edit next to the destination topic name.

3. In the Edit Table dialog box, configure the mapping information.

   Note

   • The dialog box is named Edit Schema at the database level and Edit Table at the table level. The Edit Schema dialog box has fewer parameters.

   • If you do not migrate the entire database, you cannot modify the Name of target Topic and Number of Partitions parameters in the Edit Schema dialog box.

   Parameter	Description
   Name of target Topic	The name of the topic that receives data from the source table. This defaults to the Topic you selected in the Destination Database section during the Configurations for Source and Destination Databases step. Important If the destination is a Message Queue for Apache Kafka instance, the specified topic must already exist in the destination instance. Otherwise, the data migration task fails. If the destination is a self-hosted Kafka database and the data migration task includes database and table structure migration, DTS attempts to create the specified topic in the destination database. If you change the Name of target Topic, DTS writes data to the specified topic.
   Filter Conditions	For more information, see Configure filter conditions.
   Number of Partitions	The number of partitions in the destination topic.
   Partition Key	This parameter is available when you set Policy for Shipping Data to Kafka Partitions to Ship Data to Separate Partitions Based on Hash Values of Primary Keys. You can specify one or more columns as the partition key. DTS then calculates a hash value for the specified columns and uses it to distribute rows across partitions in the destination topic. Note You can select Partition Key only in the Edit Table dialog box.

4. Click OK.