This topic describes how to migrate full data from a self-managed PostgreSQL database to an ApsaraDB RDS for PostgreSQL instance by using Data Transmission Service (DTS). DTS supports schema migration, full data migration, and incremental data migration. To migrate full data from a self-managed PostgreSQL database, you can select schema migration and full data migration when you configure a task.

Background information

Prerequisites

  • The version of the self-managed PostgreSQL database is 9.2, 9.3, 9.4, 9.5, 9.6, 10.x, 11, 12, or 13.
  • The available storage space of the ApsaraDB RDS for PostgreSQL instance is larger than the total size of the data in the self-managed PostgreSQL database.
  • The service port of the self-managed PostgreSQL database is accessible over the Internet.

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%.
  • The name of the source database cannot contain hyphens (-), for example, dts-testdata.
  • 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.
  • A single data migration task can migrate data from only one database. To migrate data from multiple databases, you must create a data migration task for each database.
  • 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 Use the failover slot feature for logical subscriptions.
    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.
  • 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 database will overwrite the data in the destination instance after the task is resumed.

Migration types

  • Schema migration

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

  • Full data migration

    DTS migrates historical data of the required objects from the self-managed PostgreSQL database to the destination database in the ApsaraDB RDS for PostgreSQL instance.

Billing

Migration type Task configuration fee Internet traffic fee
Full data migration Free of charge Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Pricing.

Permissions required for database accounts

Database Schema migration Full data migration
Self-managed PostgreSQL database The USAGE permission on pg_catalog The SELECT permission on the objects to be migrated
ApsaraDB RDS for PostgreSQL instance The CREATE and USAGE permissions on the objects to be migrated The permissions of the schema owner

For information about how to create and authorize a database account, see the following topics:

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.
    Note Functions that are written in the C programming language cannot be migrated.
  2. Migrate full data.
  3. Migrate the schemas of triggers and foreign keys.

Before you begin

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 RDS instance resides. Select a region
  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 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 an instance type based on the deployment of the source database. In this example, select User-Created Database with Public IP Address.
    Note If you select other instance types, you must deploy the network environment for the source database. For more information, see Preparation overview.
    Instance Region If the instance type is set to User-Created Database with Public IP Address, you do not need to specify the Instance Region parameter.
    Note If a whitelist is configured for the self-managed PostgreSQL database, you must add the CIDR blocks of DTS servers to the whitelist of the database. You can click Get IP Address Segment of DTS next to Instance Region to obtain the CIDR blocks of DTS servers.
    Database Type Select PostgreSQL.
    Hostname or IP Address Enter the endpoint that is used to connect to the self-managed PostgreSQL database. In this example, enter the public IP address.
    Port Number Enter the service port number of the self-managed PostgreSQL database. The default port number is 5432.
    Database Name Enter the name of the self-managed PostgreSQL database.
    Database Account Enter the account that is used to log on to the self-managed PostgreSQL database. 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 appears. If the Failed message appears, 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 RDS instance resides.
    RDS Instance ID Select the ID of the destination RDS instance.
    Database Name Enter the name of the destination database in the RDS instance. The name can be different from the name of the self-managed PostgreSQL database.
    Note Before you configure the data migration task, create a database and schema in the destination RDS instance. For more information, see Before you begin.
    Database Account Enter the database account of the destination RDS 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 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.
    Note DTS adds the CIDR blocks of DTS servers to the whitelist of the destination RDS instance. This ensures that DTS servers can connect to the destination RDS instance.
  7. Select the migration types and the objects to be migrated. Select the migration types and the objects to be migrated
    Setting Description
    Select the migration types
    • To perform only full data migration, select Schema Migration and Full Data Migration.
    • To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration.

    In this example, you must select Schema Migration and Full Data Migration.

    Note To ensure data consistency, we recommend that you do not write data to the self-managed PostgreSQL database during full data migration.
    Select the objects to be migrated

    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 schemas 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. Click Precheck.
    Note
    • A precheck is performed before the migration task starts. The migration task only starts after the precheck succeeds.
    • If the precheck fails, click the Note icon next to each failed check item to view the related details. Fix the issues as instructed and run the precheck again.
  9. After the task passes the precheck, click Next.
  10. In the Confirm Settings dialog box, specify the Channel Specification 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 a data migration task. Otherwise, the data migrated to the destination instance will be incomplete. You can wait until the data migration task automatically stops.
  12. Switch your workloads to the destination RDS instance.

What to do next

The database accounts that are used for data migration have the read and write permissions. After data migration is complete, you must delete the accounts of both the self-managed PostgreSQL database and the ApsaraDB RDS for PostgreSQL instance to ensure security.