This topic describes how to migrate data from a PolarDB-X instance to a PolarDB-X instance by using Data Transmission Service (DTS).
The source PolarDB-X instance and destination PolarDB-X instance are created. The two instances are compatible with MySQL 5.7. For more information, see Create a PolarDB-X 1.0 instance and Create a database.
The available storage space of the destination instance is larger than the total size of the data in the source instance.
Limits on the source database
Instance configuration fee
Internet traffic fee
Schema migration and full data migration
Free of charge.
Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview.
Incremental data migration
Charged. For more information, see Billing overview.
DTS migrates the schemas of objects from the source database to the destination database.
Full data migration
DTS migrates the existing data of objects from the source database to the destination database.
Incremental data migration
After full data migration is complete, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.
SQL operations that can be migrated during incremental data migration
INSERT, UPDATE, and DELETE
Permissions required for database accounts
Full data migration
Incremental data migration
PolarDB-X 1.0 instance
SELECT permission on the objects to be migrated, and REPLICATION SLAVE and REPLICATION CLIENT permissions. DTS automatically grants these permissions to the database account.
PolarDB-X 2.0 instance
Read and write permissions
- Go to the Data Migration Tasks page.
- Log on to the Data Management (DMS) console.
- In the top navigation bar, click DTS.
- In the left-side navigation pane, choose .
- From the drop-down list next to Data Migration Tasks, select the region in which the data migration instance resides. Note If you use the new DTS console, you must select the region in which the data migration instance resides in the upper-left corner.
Click Create Task. On the page that appears, configure the source and destination databases.
The name of the task. DTS automatically assigns a name to the task. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
The type of the source database. Select PolarDB-X 1.0.
The access method of the source database. Select Alibaba Cloud Instance.
The region in which the source PolarDB-X 1.0 instance resides.
Replicate Data Across Alibaba Cloud Accounts
Specifies whether to migrate data across Alibaba Cloud accounts. In this example, No is selected.
The ID of the source PolarDB-X 1.0 instance.
The database account of the source PolarDB-X 1.0 instance.
The password of the database account.
The type of the destination database. Select PolarDB-X 2.0.
The access method of the destination database. Select Alibaba Cloud Instance.
The region in which the destination PolarDB-X 2.0 instance resides.
The ID of the destination PolarDB-X 2.0 instance.
The database account of the destination PolarDB-X 2.0 instance.
The password of the database account.
In the lower part of the page for this step, click Test Connectivity and Proceed.Warning
If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database.
If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database, Alibaba Cloud database instance, or ECS security group rules, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.
After the DTS task is complete or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist or ECS security group rules.
Configure objects to synchronize and advanced settings.
To perform only full data migration, select Schema Migration and Full Data Migration.
To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.
If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
Processing Mode of Conflicting Tables
Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started.Note
You can use the object name mapping feature to rename the tables that are migrated to the destination database. You can use this feature if the source and destination databases contain tables that have identical table names and the tables in the destination database cannot be deleted or renamed. For more information, see Map object names.
Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases.Warning
If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to the following potential risks:
If the source and destination databases have the same schemas, DTS does not migrate data records that have the same primary key values as data records in the destination database.
If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
Capitalization of Object Names in Destination Instance
The capitalization of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that in the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section.
To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see the "Map the name of a single object" section of the Map object names topic.
To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see the "Map multiple object names at a time" section of the Map object names topic.
If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated.
Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts will receive notifications. Valid values:
No: does not configure alerting.
Yes: configures alerting. If you select Yes, you must also specify the alert threshold and alert contacts. For more information, see Configure monitoring and alerting.
Specify the retry time range for failed connections
The retry time range for failed connections. Valid values: 10 to 1440. Unit: minutes. Default value: 120. We recommend that you set the retry time range to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails.Note
If you set different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is set later takes precedence.
When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
Configure ETLSpecifies whether to configure the extract, transform, and load (ETL) feature. For more information, see What is ETL?. Valid values:
- Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task.
- No: does not configure the ETL feature.
In the lower part of the page, click Next: Save Task Settings and Precheck.Note
Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.
If the task fails to pass the precheck, click View Details next to each failed item. After you troubleshoot the issues based on the error message, you can run a precheck again.
If an alert is triggered for an item during the precheck:
If the alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.
If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.
Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.
On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.
New Instance Class
The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Specifications of data migration instances.
Read and select the check box to agree to the Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.