Data Transmission Service：Migrate data from Amazon Aurora PostgreSQL to an ApsaraDB RDS for PostgreSQL instance

Precautions

• DTS uses read and write resources of the source and destination databases during full data migration. This may increase the loads of the database servers. If the database performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source database, the tables have no primary keys, or a deadlock occurs in the destination database. Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. For example, you can migrate data when the CPU utilization of the source and destination databases is less than 30%.

• Amazon Aurora PostgreSQL 10.0 and earlier versions do not support incremental data migration.

• Each data migration task can migrate data from only a single database. To migrate data from multiple databases, you must create a data migration task for each database.

• DTS does not migrate functions that are written in the C programming language.

• The tables to be migrated in the source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records.

• If a data migration task fails, DTS automatically resumes the task. Before you switch your workloads to the destination instance, stop or release the data migration task. Otherwise, the data in the source instance overwrites the data in the destination instance after the task is resumed.

Billing rules

Migration types

• Schema migration

  DTS migrates the schemas of objects to the ApsaraDB RDS for PostgreSQL instance. DTS supports schema migration for the following types of objects: table, trigger, view, sequence, function, user-defined type, rule, domain, operation, and aggregate.

  Note

  DTS does not migrate functions that are written in the C programming language.

• Full data migration

  DTS migrates the existing data of objects from the Amazon RDS for PostgreSQL instance to the ApsaraDB RDS for PostgreSQL instance.

• Incremental data migration

  After full data migration is complete, DTS migrates incremental data from the Amazon RDS for PostgreSQL instance to the ApsaraDB RDS for PostgreSQL instance. Incremental data migration allows you to ensure service continuity when you migrate data from the Amazon RDS for PostgreSQL instance to the ApsaraDB RDS for PostgreSQL instance.

Permissions required for database accounts

For more information about how to create a database account and grant permissions to the account, see the following topics.

• Amazon Aurora PostgreSQL database: Understanding PostgreSQL roles and permissions

• ApsaraDB RDS for PostgreSQL instance: Create an account

Data migration process

To prevent data migration failures caused by dependencies between objects, DTS migrates the schemas and data of the source Amazon RDS for PostgreSQL instance in the following order:

1. Migrate the schemas of tables, views, sequences, functions, user-defined types, rules, domains, operations, and aggregates.

2. Perform full data migration.

3. Migrate the schemas of triggers and foreign keys.

4. Perform incremental data migration.

   Note

   Before incremental data migration, do not perform DDL operations on the objects in the Amazon RDS for PostgreSQL instance. Otherwise, the objects may fail to be migrated.

Preparation 1: Edit the inbound rule of the Amazon Aurora PostgreSQL instance

1. Log on to the Amazon Aurora console.

2. Go to the basic information page of the Amazon Aurora PostgreSQL instance.

3. Select the node that assumes the Writer role.

4. In the Connectivity & security section, click the name of the VPC security group that corresponds to the writer node.

   

5. On the Security Groups page, click the Inbound tab in the Security Group section. On the Inbound tab, click Edit. In the Edit inbound rules dialog box, add the CIDR blocks of DTS servers that reside in the corresponding region to the inbound rule. For more information, see Add the CIDR blocks of DTS servers.

   

   Note

   • You need to add only the CIDR blocks of DTS servers that reside in the same region as the destination database. For example, the source database resides in the Singapore region and the destination database resides in the China (Hangzhou) region. You need to add only the CIDR blocks of DTS servers that reside in the China (Hangzhou) region.

   • You can add all of the required CIDR blocks to the inbound rule at a time.

   • If you have other questions, see the official documentation of Amazon or contact technical support.

Preparation 2: Create a database and a schema in the destination ApsaraDB RDS for PostgreSQL instance

Create a database and a schema on the destination ApsaraDB RDS for PostgreSQL instance based on the database and schema information of the objects to be migrated. The schema name of the source and destination databases must be the same. For more information, see Create a database and Manage accounts by using schemas.

Procedure (in the new DTS console)

1. Go to the Data Migration Tasks page.

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

   2. In the top navigation bar, click DTS.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Migration.

   Note

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

   • You can also go to the Data Migration Tasks page of the new DTS console.

2. 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.

3. Click Create Task. In the Create Data Migration Task wizard, configure the source and destination databases. The following table describes the parameters.

   Warning

   After you configure the source and destination databases, we recommend that you read the limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

   Section	Parameter	Description
   N/A	Task Name	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.
   Source Database	Select a DMS database instance	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the source database. Select PostgreSQL.
   	Access Method	The access method of the source database. Select Public IP Address.
   	Instance Region	The region in which the Amazon Aurora PostgreSQL instance resides. Note If the region in which the Amazon Aurora PostgreSQL instance resides is not displayed in the drop-down list, select a region that is geographically closest to the Amazon Aurora PostgreSQL instance.
   	Hostname or IP address	The endpoint that is used to access the Amazon Aurora PostgreSQL instance. Note You can obtain the endpoint on the basic information page of the Amazon Aurora PostgreSQL instance.
   	Port Number	The service port number of the Amazon Aurora PostgreSQL instance. Default value: 5432.
   	Database Name	Enter the name of the source database in the Amazon Aurora PostgreSQL instance.
   	Database Account	The database account of the Amazon Aurora PostgreSQL instance. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account.
   Destination Database	Select a DMS database instance	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the destination database. Select PostgreSQL.
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination ApsaraDB RDS for PostgreSQL instance resides.
   	Instance ID	The ID of the destination ApsaraDB RDS for PostgreSQL instance.
   	Database Name	The name of the destination database in the ApsaraDB RDS for PostgreSQL instance. The name can be different from the name of the source database in the Amazon Aurora PostgreSQL instance. Note Before you configure the data migration task, make sure that the destination database is created in the ApsaraDB RDS for PostgreSQL instance. For more information, see Create a database.
   	Database Account	The database account of the destination ApsaraDB RDS for PostgreSQL instance. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account.

4. In the lower part of the page, click Test Connectivity and Proceed.

5. If an IP address whitelist is configured for your self-managed database, add the CIDR blocks of DTS servers to the IP address whitelist. Then, click Test Connectivity and Proceed.

   Warning

   If the public CIDR blocks of DTS servers are automatically or manually added to the whitelist of a database instance or to the security group rules of an ECS instance, 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 security group rules and forbidding unauthorized CIDR blocks, or connecting the database instance to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

6. Configure the objects to be migrated and advanced settings.

   Parameter	Description
   Migration Types	To perform full data migration only, select both Schema Migration and Full Data Migration. To migrate data without service downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note To ensure data consistency, do not write data to the source instance during data migration if Incremental Data Migration is not selected.
   Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that use 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 If the source and destination databases contain identical table names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. 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 schema, DTS does not migrate data records that have the same primary keys 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 of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
   Source Objects	Select one or more objects from the Source Objects section. Click the icon and add the objects to the Selected Objects section. Note You can select columns, tables, or schemas as the objects to be migrated. If you select tables or columns as the objects to be migrated, DTS does not migrate other objects, such as views, triggers, or stored procedures, to the destination database.
   Selected Objects	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 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. Note 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.

7. Click Next: Advanced Settings to configure advanced settings.

   • Data Verification Settings

     For more information about how to use the data verification feature, see Configure data verification.

   • Advanced Settings

     Parameter	Description
     Select the dedicated cluster used to schedule the task	By default, DTS schedules the task to a shared cluster. You do not need to configure this parameter. You can also purchase and specify a dedicated cluster of the required specifications to run the data migration task. For more information, see What is a DTS dedicated cluster.
     Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the retry time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected 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 specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified 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 requirements. You can also release the DTS instance at the earliest opportunity after the source database and destination instance are released.
     The wait time before a retry when other issues occur in the source and destination databases.	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Important The value of the The wait time before a retry when other issues occur in the source and destination databases parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
     Enable Throttling for Full Data Migration	Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only when you select Full Data Migration for the Migration Types parameter.
     Enable Throttling for Incremental Data Migration	Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only when you select Incremental Data Migration for the Migration Types parameter.
     Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is selected.
     Configure ETL	Specifies whether to enable 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.
     Monitoring and Alerting	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 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 the Configure monitoring and alerting for a new DTS task section of the "Configure monitoring and alerting" topic.

8. In the lower part of the page, click Next: Save Task Settings and Precheck.

   You can move the pointer over Next: Save Task Settings and Precheck and click Preview API Call to view the parameter settings of the API operation that is called to configure the instance.

   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 causes, run a precheck again.

   • If an alert is generated for an item during the precheck, perform the following operations based on the scenario:

     • 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.

9. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

10. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

    Section	Parameter	Description
    New Instance Class	Resource Group	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
    	Instance Class	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.

11. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

12. Click Buy and Start to start the data migration task. You can view the progress of the task on the Task Management page of the data migration task.

Procedure (in the old DTS console)

1. Log on to the DTS console.
   Note If you are redirected to the Data Management (DMS) console, you can click the icon in the lower-right corner to go to the previous version of the DTS console.
2. In the left-side navigation pane, click Data Migration.
3. At the top of the Migration Tasks page, select the region where the destination cluster resides.
4. In the upper-right corner of the page, click Create Migration Task.

5. Configure the source and destination databases.

   

   Section	Parameter	Description
   N/A	Task Name	The name of the task. DTS automatically generates a task name. We recommend that you specify a descriptive name to identify the task. You do not need to specify a unique task name.
   Source Database	Instance Type	The instance type of the source database. Select User-Created Database with Public IP Address.
   	Instance Region	The region in which the source instance resides. If you select User-Created Database with Public IP Address as the instance type, you do not need to configure the Instance Region parameter.
   	Database Type	The type of the source database. Select PostgreSQL.
   	Hostname or IP Address	The endpoint that is used to access the Amazon Aurora PostgreSQL instance. Note You can obtain the endpoint on the basic information page of the Amazon Aurora PostgreSQL instance.
   	Port Number	Enter the service port number of the Amazon Aurora PostgreSQL instance. The default port number is 5432.
   	Database Name	Enter the name of the source database in the Amazon Aurora PostgreSQL instance.
   	Database Account	The database account of the Amazon Aurora PostgreSQL instance. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account. Note After you configure the source database parameters, click Test Connectivity next to Database Password to verify whether the configured parameters are valid. If the configured parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed to modify the source database parameters based on the check results.
   Destination Database	Instance Type	The instance type of the destination database. Select RDS Instance.
   	Instance Region	The region in which the ApsaraDB RDS for PostgreSQL instance resides.
   	RDS Instance ID	The ID of the ApsaraDB RDS for PostgreSQL instance.
   	Database Name	The name of the destination database in the ApsaraDB RDS for PostgreSQL instance. The name can be different from the name of the source database in the Amazon Aurora PostgreSQL instance. Note You must create a database and a schema in the destination ApsaraDB RDS for PostgreSQL instance before you configure the data migration task. For more information, see the Preparation 2: Create a database and a schema in the destination ApsaraDB RDS for PostgreSQL instance section of this topic.
   	Database Account	The database account of the ApsaraDB RDS for PostgreSQL instance. For information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account. Note After you configure the destination database parameters, click Test Connectivity next to Database Password to verify whether the configured parameters are valid. If the configured parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed to modify the destination database parameters based on the check results.

6. In the lower-right corner of the page, click Set Whitelist and Next.

   If the source or destination database instance is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, or is a self-managed database hosted on Elastic Compute Service (ECS), DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the database instance or ECS security group rules. If the source or destination database is a self-managed database on data centers or is from other cloud service providers, you must manually add the CIDR blocks of DTS servers to allow DTS to access the database. For more information about the CIDR blocks of DTS servers, see the "CIDR blocks of DTS servers" section of the Add the CIDR blocks of DTS servers to the security settings of on-premises databases topic.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the 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: enhance the security of your username and password, limit the ports that are exposed, authenticate API calls, regularly check the whitelist or ECS security group rules and forbid unauthorized CIDR blocks, or connect the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

7. Select the objects to be migrated and the migration types.

   

   Setting	Description
   Select the migration types	To perform only full data migration, select both Schema Migration and Full Data Migration To migrate data without service downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note To ensure data consistency, do not write data to the Amazon Aurora PostgreSQL database during data migration if Incremental Data Migration is not selected.
   Select the objects to be migrated	Select one or more objects from the Available section and click the icon to move the objects to the Selected section. Note You can select columns, tables, or databases as the objects to migrate. By default, after an object is migrated, the object name in the destination database remains the same as the object name in the source database. You can use the object name mapping feature to rename the objects that are migrated to the destination database. For more information, see Object name mapping. 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.
   Specify whether to rename objects	You can use the object name mapping feature to rename the objects that are migrated to the destination instance. For more information, see Object name mapping.
   Specify the retry time range for a failed connection to the source or destination database	By default, if DTS fails to connect to the source or destination database, DTS retries within the next 12 hours. You can specify a retry time range based on your needs. If DTS reconnects to the source and destination databases within the specified period of time, DTS resumes the data migration task. Otherwise, the migration task fails. Note 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 requirements. You can also release the DTS instance at the earliest opportunity after the source and destination instances are released.

8. In the lower-right corner of the page, click 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, 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.
9. After the task passes the precheck, click Next.
10. In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.
11. Click Buy and Start to start the data migration task.
    Note We recommend that you do not manually stop the task during full data migration. Otherwise, the data migrated to the destination database will be incomplete. You can wait until the data migration task automatically stops.

    

12. Switch your workloads to the ApsaraDB RDS for PostgreSQL instance.