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Migrating Data to RDS for PostgreSQL Using psql

Updated at: Apr 20, 2020 GMT+08:00

Preparing for Data Migration

PostgreSQL supports logical backups. You can use the pg_dump logical backup function to export backup files and then import them to RDS using psql.

You can access RDS DB instances through an EIP or ECS.

Preparations

  1. Prepare an ECS for accessing DB instances in the same VPC subnet or prepare a device for accessing RDS through a public network.
    • To connect to a DB instance through an ECS, you must first create an ECS.

      For details about how to create and connect to an ECS, see How Can I Create and Connect to an ECS?

    • To connect to a DB instance through an EIP, you must:
      1. Bind the EIP to the DB instance. For details, see Binding an EIP.
      2. Ensure that the local device can access the EIP that has been bound to the DB instance.
  2. Install the PostgreSQL client on the ECS or device that was prepared in step 1.

    For details, see How Can I Install the PostgreSQL Client?

    The PostgreSQL client version must be the same as the version of RDS for PostgreSQL. The PostgreSQL database or client will provide pg_dump and psql.

Exporting Data

Before migrating an existing PostgreSQL database to RDS, you need to export the PostgreSQL database.

  • The export tool must match the DB engine version.
  • Database migration is performed offline. Before the migration, you must stop any applications using the source database.
  1. Log in to the prepared ECS or device that can access RDS DB instances.
  2. Use the pg_dump tool to export the source database into an SQL file.

    pg_dump --username=<DB_USER> --host=<DB_ADDRESS> --port=<DB_PORT> --format=plain --file=<BACKUP_FILE> <DB_NAME>

    • DB_USER indicates the database username.
    • DB_ADDRESS indicates the database address.
    • DB_PORT indicates the database port.
    • BACKUP_FILE indicates the name of the file to which the data will be exported.
    • DB_NAME indicates the name of the database to be migrated.

    Enter the database password as prompted.

    Example:

    $ pg_dump --username=root --host=192.168.151.18 --port=5432 --format=plain --file=backup.sql my_db

    Password for user root:

    After this command is executed, a backup.sql file will be generated as follows:

    [rds@localhost ~]$ ll backup.sql

    -rw-r-----. 1 rds rds 2714 Sep 21 08:23 backup.sql

Importing Data

This section describes how to use an ECS or a device that can access RDS to connect to a DB instance and import the exported SQL file into RDS.

  1. Ensure that the destination database to which data is to be imported exists.

    If the destination database does not exist, run the following command to create a database:

    # psql --host= <RDS_ADDRESS> --port=< DB_PORT> --username= root --dbname=postgres -c " create database <DB_NAME>;"
    • RDS_ADDRESS indicates the IP address of the RDS DB instance.
    • DB_PORT indicates the RDS DB instance port.
    • DB_NAME indicates the name of the database to be imported.

  2. Import the exported file into RDS.

    # psql --host=<RDS_ADDRESS> --port=<DB_PORT> --username=root --dbname=<DB_NAME> --file=<BACKUP_DIR>/backup.sql

    • RDS_ADDRESS indicates the IP address of the RDS DB instance.
    • DB_PORT indicates the RDS DB instance port.
    • DB_NAME indicates the name of the database to which data is to be imported. Ensure that the database exists.
    • BACKUP_DIR indicates the directory where the backup.sql file is stored.

    Enter the password for the RDS DB instance as prompted.

    Example:

    # psql --host=172.16.66.198 --port=5432 --username=root --dbname=my_db --file=backup.sql

    Password for user root:

  3. View the import result.

    my_db=> \l my_db

    In this example, the database named my_db has been imported.

    my_db=> \l my_db
    List of databases
    Name  | Owner | Encoding | Collate     | Ctype       | Access privileges
    ------+-------+----------+-------------+-------------+-----------
    my_db | root  | UTF8     | en_US.UTF-8 | en_US.UTF-8 | 
    (1 row)

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