This topic describes how to synchronize data from an ApsaraDB RDS for MySQL instance to a PolarDB-X V2.0 instance by using Data Transmission Service (DTS).
Supported source databasesYou can use DTS to synchronize data from the following types of MySQL databases to a PolarDB-X V2.0 instance. This topic uses an ApsaraDB RDS for MySQL instance as an example to describe how to configure a data synchronization task. You can also follow the procedure to configure data synchronization tasks for other types of MySQL databases.
- ApsaraDB RDS for MySQL instance
- Self-managed database that is hosted on Elastic Compute Service (ECS)
- Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway
- Self-managed database that is connected over Database Gateway
- Self-managed database that is connected over Cloud Enterprise Network (CEN)
- A PolarDB-X V2.0 instance is created and the storage type is MySQL 5.x.
- The available storage space of the PolarDB-X V2.0 instance is larger than the total size of the data in the ApsaraDB RDS for MySQL instance.
|Limits on the source database||
If the source database is a self-managed MySQL database, take note of the following limits:
Supported synchronization topologies
- One-way one-to-one synchronization
- One-way many-to-one synchronization
SQL operations that can be synchronized
|Operation type||SQL statements|
|DML||INSERT, UPDATE, and DELETE|
- Go to the Data Synchronization page of the new DTS console.
- In the upper-left corner of the page, select the region where the data synchronization
- Click Create Task. On the page that appears, configure the source and destination databases.Warning After you select the source and destination instances, we recommend that you read the limits displayed at the top of the page. This helps you create and run the data synchronization task.
Section Parameter Description N/A Task Name
DTS automatically generates a task name. We recommend that you specify an informative name to identify the task. You do not need to use a unique task name.
Source Database Database Type Select MySQL. Access Method Select Alibaba Cloud Instance. Instance Region Select the region where the source ApsaraDB RDS for MySQL instance resides. Replicate Data Across Alibaba Cloud Accounts In this example, select No because data is synchronized within the same Alibaba Cloud account. RDS Instance ID Select the ID of the source ApsaraDB RDS for MySQL instance. Database Account Enter the database account of the source ApsaraDB RDS for MySQL instance. The account must have the REPLICATION CLIENT, REPLICATION SLAVE, SHOW VIEW, and SELECT permissions. Database Password
Enter the password of the database account.
Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data synchronization task. For more information, see Configure SSL encryption on an ApsaraDB RDS for MySQL instance.
Destination Database Database Type Select PolarDB-X 2.0. Access Method Select Alibaba Cloud Instance. Instance Region Select the region where the destination PolarDB-X V2.0 instance resides. Instance ID Select the ID of the destination PolarDB-X V2.0 instance. Database Account Enter the database account of the destination PolarDB-X V2.0 instance. The account must have the read and write permissions. Database Password
Enter the password of the database account.
- In the lower part of the page, click Test Connectivity and Proceed.
- Select objects for the task and configure advanced settings.
- Basic Settings
Parameter Description Task Stages
Incremental Data Synchronization is selected by default. You can select only Full Data Synchronization. You cannot select Schema Synchronization. After the precheck, DTS synchronizes the historical data of the selected objects from the source instance to the destination cluster. The historical data is the basis for subsequent incremental synchronization.
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 identical table names, the precheck is passed. Otherwise, an error is returned during precheck and the data synchronization task cannot be started.Note You can use the object name mapping feature to rename the tables that are synchronized to the destination database. You can use this feature if the source and destination databases contain 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 consistency is not guaranteed and your business may be exposed to potential risks.
- If the source and destination databases have the same schema, and a data record has
the same primary key as an existing data record in the destination database:
- During full data synchronization, DTS does not synchronize the data record to the destination database. The existing data record in the destination database is retained.
- During incremental data synchronization, DTS synchronizes the data record to the destination database. The existing data record in the destination database is overwritten.
- If the source and destination databases have different schemas, data may fail to be initialized. In this case, only some columns are synchronized or the data synchronization task fails.
- If the source and destination databases have the same schema, and a data record has the same primary key as an existing data record in the destination database:
Select one or more objects from the Source Objects section and click the icon to move the objects to the Selected Objects section.Note You can select columns, tables, or databases as the objects to be synchronized.
Rename Databases and Tables
- To rename an object that you want to synchronize to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
- To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
You can specify WHERE conditions to filter data. For more information, see Use SQL conditions to filter data.
Select the SQL operations to be synchronized In the Selected Objects section, right-click an object. In the dialog box that appears, select the DML operations that you want to synchronize. For more information, see SQL operations that can be synchronized.
- Advanced Settings
Parameter Description Set AlertsSpecify whether to set alerts for the data synchronization task. If the task fails or the synchronization latency exceeds the threshold, the alert contacts will receive notifications.
- Select No if you do not want to set alerts.
- Select Yes to set alerts. In this case, you must also set the alert threshold and alert contacts.
Capitalization of Object Names in Destination Instance
Specify 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 of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Replicate Temporary Tables When DMS Performs DDL OperationsIn this scenario, DTS does not synchronize DDL operations. You must set this parameter to No. However, DTS may support DDL operations for this scenario in the future. In this case, if you use Data Management (DMS) to perform online DDL operations on the source database, you can specify whether to synchronize temporary tables generated by the operations.
- Yes: DTS synchronizes the data of temporary tables generated by online DDL operations.
Note If online DDL operations generate a large amount of data, the data synchronization task may be delayed.
- No: DTS does not synchronize the data of temporary tables generated by online DDL operations.
Only the original DDL data of the source database is synchronized.
Note If you select No, the tables in the destination database may be locked.
Retry Time for Failed ConnectionSpecify the retry time for failed connections. Valid values: 10 to 1440. Unit: minutes. Default value: 120. We recommend that you set the retry time to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.Note
- If multiple DTS instances have the same source or destination database, the lowest value takes effect. For example, the retry time is set to 30 minutes for Instance A and 60 minutes for Instance B, DTS retries failed connections at an interval of 30 minutes.
- When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
- Basic Settings
- Click Next: Save Task Settings and Precheck in the lower part of the page. Note
- Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization task only after the task passes the precheck.
- If the task fails to pass the precheck, you can click the icon next to each failed item to view details.
- You can troubleshoot the issues based on the causes and run a precheck again.
- If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
- Wait until the Success Rate becomes 100%. Then, click Next: Purchase Instance.
- On the Purchase Instance page, specify the Billing Method and Instance Class parameters for the data synchronization
instance. The following table describes the parameters.
Section Parameter Description Parameters Billing Method
- Subscription: You can pay for your subscription when you create an instance. We recommend that you select the subscription billing method for long-term use because it is more cost-effective than the pay-as-you-go billing method. You can save more costs with longer subscription periods.
- Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. We recommend that you select the pay-as-you-go billing method for short-term use. If you no longer require your pay-as-you-go instance, you can release it to reduce costs.
Instance Class DTS provides several instance classes that have different performance in synchronization speed. You can select an instance class based on your business scenario. For more information, see Specifications of data synchronization instances. Subscription Length If you select the subscription billing method, set the subscription length and the number of instances that you want to create. The subscription length can be one to nine months or one to three years.Note This parameter is available only if you select the subscription billing method.
- Read and select Data Transmission Service (Pay-as-you-go) Service Terms.
- Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.