This topic describes how to synchronize data from an ApsaraDB RDS for MySQL instance to an ApsaraDB RDS for PostgreSQL instance by using Data Transmission Service (DTS).
- A source ApsaraDB RDS for MySQL instance is created. For more information, see Create an ApsaraDB RDS for MySQL instance.
- A destination ApsaraDB RDS for PostgreSQL instance is created. For more information, see Create an ApsaraDB RDS for PostgreSQL instance.
- The available storage space of the destination instance is larger than the total size of the data in the source instance.
Supported synchronization topologies
- One-way one-to-one synchronization
- One-way one-to-many 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 Tasks page.
- Log on to the DMS console.
- In the top navigation bar, click DTS.
- In the left-side navigation pane, choose .
- On the right side of Data Synchronization Tasks, select the region where the data synchronization instance resides. Note If you use the new DTS console, you must select the region where the data synchronization instance resides in the top navigation bar.
- Click Create Task. On the page that appears, configure the source and destination databases.
Section Parameter Description N/A Task Name
The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to use a unique task name.
Source Database Database Type Select MySQL. Access Method Select Cloud Instance. Instance Region The region where the source ApsaraDB RDS for MySQL instance resides. Replicate Data Across Alibaba Cloud Accounts In this example, No is selected 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. Database Password
The password of the database account.
Select Non-encrypted or SSL-encrypted based on your requirements. If you want to select SSL-encrypted, you must enable SSL encryption for the source instance before you configure the data migration task. For more information, see Configure SSL encryption for an ApsaraDB RDS for MySQL instance.
Destination Database Database Type Select PostgreSQL. Access Method Select Cloud Instance. Instance Region Select the region where the destination ApsaraDB RDS for PostgreSQL instance resides. Instance ID Select the ID of the destination ApsaraDB RDS for PostgreSQL instance. Database Name Enter the name of the destination ApsaraDB RDS for PostgreSQL instance. Database Account Enter the database account of the destination ApsaraDB RDS for PostgreSQL instance. The account must have the permissions of the schema owner. For more information about how to create an account on an ApsaraDB RDS for PostgreSQL instance and grant permissions to this account, see Create an account on an ApsaraDB RDS for PostgreSQL instance. Database Password
The password of the database account.
- In the lower part of the page, click Test Connectivity and Proceed. Note
- You do not need to modify the security settings for ApsaraDB instances (such as ApsaraDB RDS for MySQL and ApsaraDB for MongoDB) and ECS-hosted databases. DTS automatically adds the CIDR blocks of DTS servers to the whitelists of ApsaraDB instances or the security group rules of ECS instances. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
- After data synchronization is complete, we recommend that you remove the CIDR blocks of DTS servers from the whitelists or security groups.
- Select the objects to migrate.
- Basic Settings
Parameter Description Task Stages
Incremental Data Synchronization is selected by default. You must also select Schema Synchronization and Full Data Synchronization. After the precheck is completed, DTS synchronizes the historical data of selected objects from the source database 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 the precheck and the data synchronization 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 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 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, initial data synchronization may fail. In this case, only part of the 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:
Capitalization of Object Names in Destination Instance
Specifies 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.
Select one or more objects from the Source Objects section and click the icon to add the objects to the Selected Objects section.Note You can select columns, tables, or databases as objects to synchronize. If you select tables or columns as the objects to synchronize, DTS does not synchronize other objects such as views, triggers, and stored procedures to the destination database.
Note The time field supports the TIMESTAMP data type. If the time field of the source database is 0, the time field of the destination database is automatically converted to null.
- To rename an object in 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 in the destination instance, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
- Advanced Settings
Parameter Description Set AlertsSpecifies whether to set alerts for the data synchronization task. If you select yes, DTS sends notifications to contacts if the task fails or the synchronization latency exceeds the upper limit.
- No: does not set alerts.
- Yes: sets alerts. In this case, you must also set the alert threshold and alert contacts.
Retry Time for Failed ConnectionSpecifies 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 time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.Note
- If an instance serves as the source or destination database of multiple data synchronization tasks, the less value that is specified for the instance 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 ETLSpecify whether you want to enable the ETL feature. For more information, see What is ETL?.
- If you select Yes, the ETL feature is enabled. You must specify a policy in the text box.
- If you select No, the ETL feature is disabled.
- 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.
- After you troubleshoot the issues based on the causes, you can 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 specifications for the data synchronization
instance. The following table describes related parameters.
Section Parameter Description Parameters Billing method
- Subscription: You pay for your subscription when you create an instance. The subscription billing method is more cost-effective than the pay-as-you-go billing method for long-term use.
- Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. For short-term use, we recommend that you select the pay-as-you-go billing method. If you no longer need a pay-as-you-go instance, you can release the instance 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 Duration If you select the subscription billing method, set the subscription duration and the number of instances that you want to create. The subscription duration 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.