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.
  • An AnalyticDB for PostgreSQL instance is created. For more information, see Create an 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 run the following statement on the new tables before they can be synchronized:
    ALTER TABLE schema.table REPLICA IDENTITY FULL;

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. You must also restart the data synchronization task.

SQL operations that can be synchronized

Only INSERT, UPDATE, and DELETE operations can be synchronized.

Preparations

  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 modification. We recommend that you evaluate the impact on your business and change the setting during off-peak hours.
    1. Log on to the ApsaraDB for RDS console.
    2. In the upper-left corner of the page, select the region where the RDS instance resides.
    3. Find the target 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 reference.

Procedure

  1. Purchase a data synchronization instance. For more information, see Purchase procedure.
    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 databases.
    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 region of the source instance. The region is the same as the source region that you selected when you purchased the data synchronization instance. 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.
    Note The account must have the owner permission on schemas.
    Database Password Enter the password of the source database account.
    Destination Instance Details Instance Type The value of this parameter is set to AnalyticDB for PostgreSQL and cannot be changed.
    Instance Region The region of the destination instance. The region is the same as the destination region that you selected when you purchased the data synchronization instance. 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 destination database must exist in the ApsaraDB RDS for PostgreSQL instance. For more information, see Create a database.
    Database Account Enter the database account of the AnalyticDB for PostgreSQL instance.
    Note The database account must have the SELECT, INSERT, UPDATE, DELETE, COPY, TRUNCATE, and ALTER TABLE permissions.
    Database Password Enter the password of the destination 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 source ApsaraDB RDS for PostgreSQL instance and the destination AnalyticDB for PostgreSQL instance. This ensures that DTS servers can connect to the source and destination instances.
  8. Configure the synchronization policy and objects.
    Select the objects to be synchronized
    Section Parameter Description
    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.
    Processing Mode In Existed Target Table
    • 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
    • Alter Table
    Objects to be synchronized N/A

    Select tables from the Available section and click the Right arrow icon to move the tables to the Selected section.

    Note
    • You can select only tables as the objects to be synchronized.
    • You can change the names of the columns that are synchronized to the destination database by using the object name mapping feature. For more information about how to use this feature, see Specify the name of an object in the destination instance.
  9. In the lower-right corner of the page, click Precheck.
    Note
    • Before you can start the data synchronization task, a precheck is performed. You can start the data synchronization task only after the task passes the precheck.
    • If the task fails to pass the precheck, click the Info icon icon next to each failed item to view details. Troubleshoot the issues based on the causes and run the precheck again.
  10. Close the Precheck dialog box after the following message is displayed: The precheck is passed.
  11. Wait until the initial synchronization is complete and the data synchronization task is in the Synchronizing state.
    On the Synchronization Tasks page, view the status of the data synchronization task.View the status of a data synchronization task.