This topic describes how to migrate full data from an Amazon RDS for PostgreSQL instance to an ApsaraDB RDS for PostgreSQL instance by using Data Transmission Service (DTS).

Prerequisites

  • An Amazon RDS for PostgreSQL instance is created and the database engine version is 9.4, 9.5, 9.6, or 10.0.
  • The Public accessibility option of the Amazon RDS for PostgreSQL instance is set to Yes. This ensures that DTS can access the instance over the Internet.
  • An ApsaraDB RDS for PostgreSQL instance is created. For more information, see Create an ApsaraDB RDS for PostgreSQL instance.
    Note The database engine version of the ApsaraDB RDS for PostgreSQL instance is 9.4 or 10.0.
  • The available storage space of the ApsaraDB RDS for PostgreSQL instance is larger than the total size of the data in the Amazon 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%.
  • Incremental data migration is not supported in this scenario. Before you start the data migration task, you must stop the services that run on the Amazon RDS for PostgreSQL instance. To ensure data consistency, we recommend that you do not write data to the Amazon RDS for 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.
  • To ensure that the data migration task runs as expected, you can perform a primary/secondary switchover only on an ApsaraDB RDS for PostgreSQL instance V11. In this case, you must set the rds_failover_slot_mode parameter to sync. For more information, see Logical Replication Slot Failover.
    Warning If you perform a primary/secondary switchover on a self-managed PostgreSQL database or an ApsaraDB RDS for PostgreSQL instance of other versions, the data migration task stops.

Billing

Migration type Task 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 Pricing.

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

Database Schema migration Full data migration
Amazon RDS PostgreSQL The USAGE permission on pg_catalog The SELECT permission on the objects to migrate
ApsaraDB RDS for PostgreSQL The CREATE and USAGE permissions on the objects to migrate Permissions of the schema owner

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 RDS for PostgreSQL instance

  1. Log on to the Amazon RDS Management Console.
  2. Go to the Basic Information page of the Amazon RDS for PostgreSQL instance.
  3. In the Security group rules section, click the name of the security group corresponding to the existing inbound rule.
    Security group rule
  4. 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.
    Edit the inbound rule of the Amazon RDS for PostgreSQL instance
    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 (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.

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

Create a database and schema in the destination ApsaraDB RDS instance based on the database and schema information of the objects to migrate. 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.
    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 specify a unique task name.
    Source Instance Details Instance Type Select User-Created Database with Public IP Address.
    Instance Region The region where the source instance resides. If you select User-Created Database with Public IP Address for the instance type, you do not need to specify the Instance Region parameter.
    Database Type Select PostgreSQL.
    Hostname or IP Address The endpoint that is used to access the Amazon RDS for PostgreSQL instance.
    Note You can find the endpoint on the Basic Information page of the Amazon RDS for PostgreSQL instance.
    Endpoint
    Port Number The service port number of the Amazon RDS for PostgreSQL instance. Default value: 5432.
    Database Name The name of the source database in the Amazon RDS for PostgreSQL instance.
    Database Account The database account of the Amazon RDS for PostgreSQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password 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 appears. If the Failed message appears, click Check next to Failed. Modify the source database parameters based on the check results.
    Destination Instance Details Instance Type Select RDS Instance.
    Instance Region The region where 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 RDS for 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 ApsaraDB RDS instance.
    Database Account The database account of the ApsaraDB RDS for PostgreSQL instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password 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 appears. If the Failed message appears, 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.
  7. Select migration types and the objects to migrate.
    Select migration types and the objects to migrate
    Setting Description
    Select migration types Select Schema Migration and Full Data Migration. In this scenario, Incremental Data Migration is not supported.
    Note To ensure data consistency, we recommend that you do not write data to the Amazon RDS for PostgreSQL instance during data migration.
    Select objects to migrate

    Select one or more objects from the Available section and click the Rightwards arrow icon to add 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 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 ApsaraDB RDS instance. For more information, see Object name mapping.
    Specify the retry time range 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 following 12 hours. You can specify the retry time range based on your business requirements. If DTS is reconnected to the source and destination databases within the specified time range, 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 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.
  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 Info icon 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.
    Full data migration
  12. Switch your workloads to the ApsaraDB RDS for PostgreSQL instance.