Data Transmission Service:Migrate full data from an Amazon Aurora PostgreSQL instance 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%.
• You cannot use DTS to migrate incremental data from an Amazon Aurora PostgreSQL instance to an ApsaraDB RDS for PostgreSQL instance. Before you start the data migration task, you must stop the services that run on the Amazon Aurora PostgreSQL instance. To ensure data consistency, we recommend that you do not write data to the Amazon Aurora PostgreSQL instance during 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.
• Functions that are written in the C programming language cannot be migrated.
• 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. Therefore, 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

Migration types

• Schema migration

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

• Full data migration

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

Permissions required for database accounts

Process of full data migration

To prevent data migration failures caused by dependencies between objects, DTS migrates the schemas and data of the source PostgreSQL database 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.

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 to add the CIDR blocks of DTS servers in the corresponding region to the inbound rule. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
   

   Note

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

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

Create a database and schema in the destination RDS 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 on an ApsaraDB RDS for PostgreSQL instance and Appendix: User and schema management.

Procedure

1. Log on to 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	DTS automatically generates a task name. We recommend that you specify an informative name for easy identification. You do not need to use a unique task name.
   Source Database	Instance Type	Select User-Created Database with Public IP Address.
   	Instance Region	Select the region where the source instance resides. If the instance type is set to User-Created Database with Public IP Address, you do not need to specify the instance region.
   	Database Type	Select PostgreSQL.
   	Hostname or IP Address	Enter the endpoint that is used to access the Amazon Aurora PostgreSQL instance. Note You can find 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	Enter the database account of the Amazon Aurora PostgreSQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	Enter the password of the database account. Note After you specify the source database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed. Modify the source database parameters based on the check results.
   Destination Database	Instance Type	Select RDS Instance.
   	Instance Region	Select the region where the destination ApsaraDB RDS for PostgreSQL instance resides.
   	RDS Instance ID	Select the ID of the destination ApsaraDB RDS for PostgreSQL instance.
   	Database Name	Enter 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, you must create a database and schema in the ApsaraDB RDS for PostgreSQL instance. For more information, see Preparation 2: Create a database and schema in the destination RDS instance.
   	Database Account	Enter the database account of the destination ApsaraDB RDS for PostgreSQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
   	Database Password	Enter the password of the database account. Note After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid. If the specified parameters are valid, the Passed message is displayed. If the Failed message is displayed, click Check next to Failed. Modify the destination database parameters based on the check results.

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

   • 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. 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 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.
   • If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the 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: enhance the security of your account 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.
   • After the DTS task is completed or released, we recommend that you manually detect and remove the added CIDR blocks from the whitelist of the database instance or ECS security group rules.
7. Select the migration types and the objects to be migrated.
   

   Setting	Description
   Select the migration types	Select Schema Migration and Full Data Migration. In this data migration task, Incremental Data Migration is not supported. Note To ensure data consistency, we recommend that you do not write data to the Amazon Aurora PostgreSQL instance during data migration.
   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 be migrated. By default, after an object is migrated to the destination database, the name of the object remains unchanged. 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 for failed connections 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 the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data migration task. Otherwise, the data migration task fails. Note 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.

8. In the lower-right corner of the page, click Precheck.
   Note

   • Before you can start the data migration task, a precheck is performed. 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.