This topic describes how to synchronize data from a user-created MySQL database connected over Express Connect, VPN Gateway, or Smart Access Gateway to an AnalyticDB for PostgreSQL instance by using Data Transmission Service (DTS). The data synchronization feature allows you to transfer and analyze data with ease.

Prerequisites

  • The version of the user-created MySQL database is 5.1, 5.5, 5.6, 5.7, or 8.0.
  • The tables to be synchronized from the source database contain primary keys.
  • The binary logging feature is enabled for the source database. A database account is created for the data synchronization task. For more information, see Create an account for a user-created MySQL database and configure binary logging.
    Note The account must have the REPLICATION SLAVE permission, the REPLICATION CLIENT permission, the SHOW VIEW permission, and the permission to perform SELECT operations on the required objects.
  • The on-premises network to which the user-created MySQL database belongs is connected to Alibaba Cloud VPC over Express Connect, VPN Gateway, or Smart Access Gateway. DTS is allowed to access the network to which Express Connect, VPN Gateway, or Smart Access Gateway belongs. For more information, see Allow DTS to access the network connected over Express Connect, VPN Gateway, or Smart Access Gateway.
    Note For more information about how to connect a VPC to an on-premises data center, see Connect to local IDCs.
  • An AnalyticDB for PostgreSQL instance is created. For more information, see Create an instance.

Precautions

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 you synchronize data, 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 usage of the source and destination databases is 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.

SQL operations that can be synchronized

  • 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 buy page, set Source Instance to MySQL, 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 instances
    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 User-Created Database Connected over Express Connect, VPN Gateway, or Smart Access Gateway.
    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.
    Peer VPC Select the ID of the VPC that is connected to the user-created MySQL database.
    Database Type The value of this parameter is set to MySQL and cannot be changed.
    IP Address Enter the server IP address of the user-created MySQL database.
    Port Number Enter the service port number of the user-created MySQL database. The default port number is 3306.
    Database Account Enter the account of the user-created MySQL database.
    Note The account must have the REPLICATION SLAVE permission, the REPLICATION CLIENT permission, the SHOW VIEW permission, and the permission to perform SELECT operations on the required objects.
    Database Password Enter the password for 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 destination AnalyticDB for PostgreSQL instance.
    Database Name Enter the name of the destination database.
    Database Account Enter the database account of the destination AnalyticDB for PostgreSQL instance.
    Note The account must have the SELECT, INSERT, UPDATE, DELETE, COPY, TRUNCATE, and ALTER TABLE permissions.
    Database Password Enter the password for the destination 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 whitelist of the destination AnalyticDB for PostgreSQL instance. This ensures that DTS servers can connect to the destination AnalyticDB for PostgreSQL instance.
  8. Configure the synchronization policy and objects.
    Synchronize data from MySQL to AnalyticDB for PostgreSQL
    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 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.

    • 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. 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. For more information about primary key columns and distribution columns, see Table constraints and Partition keys.
  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. Then, the data synchronization task starts.
  12. 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.