This topic describes how to synchronize data from an ApsaraDB RDS for PostgreSQL instance to an AnalyticDB for PostgreSQL instance by using Data Transmission Service (DTS). The data synchronization feature provided by DTS allows you to transfer and analyze data with ease.

Prerequisites

  • The tables to be synchronized from the ApsaraDB RDS for PostgreSQL instance contain primary keys.
  • The destination AnalyticDB for PostgreSQL instance is created. For more information, see Create an AnalyticDB for PostgreSQL instance.

Precautions

  • A single data synchronization task can synchronize data from only one database. To synchronize data from multiple databases, you must create a data synchronization task for each database.
  • During data synchronization, new tables that are created in the source database can also be synchronized. However, to ensure data consistency, you must execute the following statement on the new tables before they can be synchronized:
    ALTER TABLE schema.table REPLICA IDENTITY FULL;
  • To ensure that the data synchronization task runs as expected, you can perform 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 primary/secondary switchover on a self-managed PostgreSQL database or an ApsaraDB RDS for PostgreSQL instance of other versions, the data synchronization task stops.

Limits

  • Initial schema synchronization is not supported. DTS does not synchronize the schemas of the required objects from the source database to the destination database.
  • You can select only tables as the objects to be synchronized.
  • You cannot synchronize the following types of data: BIT, VARBIT, GEOMETRY, ARRAY, UUID, TSQUERY, TSVECTOR, and TXID_SNAPSHOT.
  • If you perform a DDL operation on an object to be synchronized in the source database during data synchronization, you must perform the operation in the destination database. Then, you must restart the data synchronization task.

SQL operations that can be synchronized

INSERT, UPDATE, and DELETE

Before you begin

  1. Change the value of the wal_level parameter for the source RDS instance.
    Warning After you change the value of the wal_level parameter, you must restart the instance to apply the change. We recommend that you evaluate the impact on your business and change the parameter setting during off-peak hours.
    1. Log on to the ApsaraDB RDS console.
    2. In the top navigation bar, select the region where the RDS instance resides.
    3. Find the RDS instance and click its ID.
    4. In the left-side navigation pane, click Parameters.
    5. On the Parameters page, find the wal_level parameter and change the parameter value to logical.
  2. Create a database, schema, and table in the destination AnalyticDB for PostgreSQL instance based on the schema of the objects to be synchronized. For more information, see SQL statements.

Procedure

  1. Purchase a data synchronization instance. For more information, see Purchase a DTS instance.
    Note On the buy page, set Source Instance to PostgreSQL, set Target Instance to AnalyticDB for PostgreSQL, and set Synchronization Topology to One-Way Synchronization.
  2. Log on to the DTS console.
  3. In the left-side navigation pane, click Data Synchronization.
  4. At the top of the Synchronization Tasks page, select the region where the destination instance resides.
    Select a region
  5. Find the data synchronization instance and click Configure Synchronization Channel in the Actions column.
  6. Configure the source and destination instances.
    Configure the source and destination databases
    Section Parameter Description
    N/A Synchronization 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 Instance Details Instance Type Select RDS Instance.
    Instance Region The source region that you selected on the buy page. You cannot change the value of this parameter.
    Instance ID Select the ID of the ApsaraDB RDS for PostgreSQL instance.
    Database Name Enter the name of the source database.
    Database Account Enter the database account of the ApsaraDB RDS for PostgreSQL instance. The database account must have the SUPERUSER permission.
    Note If the source database runs on an ApsaraDB RDS for PostgreSQL instance V9.4 and you synchronize only DML operations, the database account must have the REPLICATION permission.
    Database Password Enter the password of the database account.
    Destination Instance Details Instance Type This parameter is set to AnalyticDB for PostgreSQL and cannot be changed.
    Instance Region The destination region that you selected on the buy page. You cannot change the value of this parameter.
    Instance ID Select the ID of the AnalyticDB for PostgreSQL instance.
    Database Name Enter the name of the destination database.
    Note The database must exist in the AnalyticDB for PostgreSQL instance. Otherwise, you must create a database.
    Database Account Enter the initial account of the AnalyticDB for PostgreSQL instance. For more information, see Create a database account.
    Note You can also enter an account that has the RDS_SUPERUSER permission. For more information, see Manage users and permissions.
    Database Password Enter the password of the database account.
  7. In the lower-right corner of the page, click Set Whitelist and Next.
    Note DTS adds the CIDR blocks of DTS servers to the whitelists of the ApsaraDB RDS for PostgreSQ and AnalyticDB for PostgreSQL instances. This ensures that DTS servers can connect to the source and destination instances.
  8. Select the synchronization policy and the objects to be synchronized.
    Select the objects to be synchronized
    Setting Parameter Description
    Select the synchronization policy Initial Synchronization Initial Full Data Synchronization is selected by default. After the precheck, DTS synchronizes historical data of the required objects from the source instance to the destination instance. The data is the basis for subsequent incremental synchronization.
    Select the processing mode of conflicting tables
    • Clear Target Table

      Skips the Schema Name Conflict item during the precheck. Clears the data in the destination table before initial full data synchronization. If you want to synchronize your business data after testing the data synchronization task, you can select this mode.

    • Ignore

      Skips the Schema Name Conflict item during the precheck. Adds data to the existing data during initial full data synchronization. If you want to synchronize data from multiple tables to one table, you can select this mode.

    Synchronization Type

    Select the types of operations that you want to synchronize based on your business requirements.

    Note The Alter Table operation is not supported.
    • Insert
    • Update
    • Delete
    • AlterTable
    Select the objects to be synchronized N/A

    Select one or more tables from the Available section and click the Rightwards arrow icon to move the tables to the Selected section.

    Note
    • You can select only tables as the objects to be synchronized.
    • You can use the object name mapping feature to rename the columns that are synchronized to the destination database. For more information, see Rename an object to be synchronized.
    N/A
    N/A
  9. In the lower-right corner of the page, click Precheck.
    Note
    • Before you can start the data synchronization task, DTS performs a precheck. The data synchronization task can be started only after it 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.
  10. Close the Precheck dialog box after the following message is displayed: The precheck is passed. Then, the data synchronization task starts.
  11. Wait until the initial synchronization is complete and the data synchronization task is in the Synchronizing state.
    You can view the status of the data synchronization task on the Synchronization Tasks page. View the status of a data synchronization task