This topic describes how to synchronize data from an ApsaraDB RDS for MySQL 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 MySQL instance contain primary keys.
  • An AnalyticDB for PostgreSQL instance is created. For more information, see Create an instance.

Notes

DTS uses read and write resources of the source and destination databases during initial full data synchronization. This may increase the database load. 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 synchronizing data, you must evaluate the performance of the source and destination databases. We recommend that you synchronize data during off-peak hours. For example, you can synchronize data when the CPU loads of the source and destination databases are less than 30%.

Limits

  • 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.
  • We recommend that you do not use gh-ost or pt-online-schema-change to perform DDL operations on objects during data synchronization. Otherwise, data synchronization may fail.

Supported SQL operations

  • DML operations: INSERT, UPDATE, and DELETE
  • DDL operations: ADD COLUMN, and RENAME COLUMN
    Note The CREATE TABLE operation is not supported. To synchronize data from a new table, you must add the table to the selected objects. For more information, see Add an object to a data synchronization task.

Supported synchronization topologies

  • One-way one-to-one synchronization
  • One-way one-to-many synchronization
  • One-way many-to-one synchronization

Term mappings

Term in MySQL Term in AnalyticDB for PostgreSQL
Database Schema
Table Table

Procedure

  1. Purchase a data synchronization instance. For more information, see Purchase procedure.
    Note On the purchase page, select MySQL for the source instance and AnalyticDB for PostgreSQL for the destination instance. Select One-Way Synchronization as the synchronization topology.
  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 instances
    Section Parameter Description
    Synchronization Task Name N/A DTS automatically generates a task name. We recommend that you use 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 value is the same as that you selected when purchasing the data synchronization instance. You cannot change the value of this parameter.
    Instance ID Select the ID of the source RDS instance.
    Database Account Enter the database account for the source ApsaraDB RDS for MySQL instance.
    Note If the database type of the source RDS instance is MySQL 5.5 or MySQL 5.6, you do not need to configure the database account and database password.
    Database Password Enter the password for the database account.
    Encryption Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the RDS instance before configuring the data synchronization task. For more information, see Configure SSL encryption for an RDS for MySQL instance.
    Note The Encryption parameter is available only in mainland China and Hong Kong(China).
    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 value is the same as that you selected when purchasing the data synchronization instance. You cannot change the value of this parameter.
    Instance ID Select the ID of the destination AnalyticDB for PostgreSQL instance.
    Database Name The name of the destination database.
    Database Account Enter the database account for the destination 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 for the database account.
  7. In the lower-right corner of the page, click Set Whitelist and Next.
    Note The CIDR blocks of DTS servers are automatically added to the whitelists of the source and destination instances. This ensures that DTS servers can connect to the source and destination instances.
  8. Configure the synchronization policy and objects.
    Configure the synchronization policy and objects
    Section Parameter Description
    Synchronization policy Initial Synchronization You must select both Initial Schema Synchronization and Initial Full Data Synchronization in most cases. After the precheck, DTS synchronizes the schemas and data of the required objects from the source instance to the destination instance. The schemas and data are 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 new data to the existing data during initial full data synchronization. You can select this mode if you want to synchronize data from multiple tables to one table.

    Synchronization Type

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

    • Insert
    • Update
    • Delete
    • Alter Table
    Objects to be synchronized N/A

    Select tables from the Available section and click the right arrow (Right arrow) icon to add the tables to the Selected section.

    Note
    • You can select only tables as the objects to be synchronized.
    • You can change the names of columns in the destination database by using the object name mapping feature provided by DTS. For more information about how to use this feature, see Specify the name of an object in the destination instance.
  9. Specify the primary key column and distribution column of the table that you want to synchronize to the AnalyticDB for PostgreSQL instance.
    Note The page in this step appears only if you select Initial Schema Synchronization.
  10. 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.
  11. Close the Precheck dialog box after the following message is displayed: The precheck is passed.
  12. 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.