AnalyticDB for MySQL is a real-time online analytical processing (RT-OLAP) service developed by Alibaba Cloud for online data analysis with high concurrency. AnalyticDB for MySQL can analyze petabytes of data from multiple dimensions at millisecond-level timing to provide you with data-driven insights into your business. This topic describes how to synchronize data from an Apsara PolarDB for MySQL cluster to an AnalyticDB for MySQL cluster by using Data Transmission Service (DTS). AnalyticDB for MySQL allows you to build internal business intelligence (BI) systems, interactive query systems, and real-time report systems.

Prerequisites

  • An AnalyticDB for MySQL cluster is created. For more information, see Create an AnalyticDB for MySQL cluster.
  • The destination AnalyticDB for MySQL cluster has sufficient storage space.
  • The binary logging feature is enabled for the Apsara PolarDB for MySQL cluster. For more information, see Enable binary logging.

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 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 usage of the source and destination databases is less than 30%.
  • 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.
  • If the disk space usage of nodes in an AnalyticDB for MySQL cluster reaches 80%, the cluster is locked. We recommend that you estimate the required disk space based on the objects to be synchronized. You must ensure that the destination cluster has sufficient storage space.

SQL operations that can be synchronized

  • DDL operations: CREATE TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE, ADD COLUMN, and DROP COLUMN
  • DML operations: INSERT, UPDATE, and DELETE
Note If the data type of a field in the source table is changed during data synchronization, an error message is generated and the data synchronization task stops. You can submit a ticket or manually troubleshoot the issue. For more information, see Troubleshoot the synchronization failure that occurs due to field type changes.

Permissions required for database accounts

Database Required permission
Apsara PolarDB for MySQL The read permission for the objects to be synchronized
AnalyticDB for MySQL The read/write permissions for the objects to be synchronized

For more information about how to create and authorize a database account, see Create an Apsara PolarDB for MySQL database account and Create an AnalyticDB for MySQL database account.

Data type mapping

For more information, see Data type mappings for initial schema synchronization.

Procedure

  1. Purchase a data synchronization instance. For more information, seePurchase procedure.
    Note On the buy page, set Source Instance to PolarDB, Target Instance to AnalyticDB for MySQL, and 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 use an informative name for easy identification. You do not need to use a unique task name.
    Source Instance Details Instance Type The value of this parameter is set to PolarDB Instance and cannot be changed.
    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.
    PolarDB Instance ID Select the ID of the source PolarDB cluster.
    Database Account Enter the database account of the source PolarDB cluster. For more information about permissions required for the account, see Permissions required for database accounts.
    Database Password Enter the password for the source database account.
    Destination Instance Details Instance Type The value of this parameter is set to AnalyticDB 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.
    Version Select 3.0.
    Database Select the ID of the destination AnalyticDB for MySQL cluster.
    Database Account Enter the database account of the AnalyticDB for MySQL cluster. For more information about permissions required for the account, see Permissions required for database accounts.
    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 whitelists of the Apsara PolarDB for MySQL cluster and the AnalyticDB for MySQL cluster. This ensures that DTS servers can connect to the source and destination clusters.
  8. Configure the synchronization policy and objects.
    Configure the synchronization policy and objects
    Parameter Description
    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 cluster. The schemas and data are the basis for subsequent incremental synchronization.
    Processing Mode In Existed Target Table
    • Pre-check and Intercept: checks whether the destination database contains tables that have the same names as tables in the source database. If the destination database does not contain tables that have the same names as tables in the source database, the precheck is passed. Otherwise, an error is returned during precheck and the data synchronization task cannot be started.
      Note If tables in the destination database have the same names as tables in the source database, and cannot be deleted or renamed, you can use the object name mapping feature. For more information, see Specify the name of an object in the destination instance.
    • Ignore: skips the precheck for identical table names in the source and destination databases.
      Warning If you select Ignore, data consistency is not guaranteed and your business may be exposed to potential risks.
      • If the source and destination databases have the same schema, DTS does not synchronize data records that have the same primary keys as data records in the destination database.
      • If the source and destination databases have different schemas, initial data synchronization may fail. In this case, only some columns are synchronized or the data synchronization task fails.
    Merge Multi Tables
    • If you select Yes, DTS adds the __dts_data_source column to each table to record data sources. In this case, DDL operations cannot be synchronized.
    • No is selected by default. In this case, DDL operations can be synchronized.
    Note You can merge the data source columns based on tasks rather than tables. To merge only the data source columns of some tables, you can create two data synchronization tasks.
    Synchronization Type Select the types of operations that you want to synchronize based on your business requirements. All operation types are selected by default.
    Note Only INSERT, UPDATE, DELETE, and ADD COLUMN operations can be synchronized.
    Objects to be synchronized

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

    You can select tables and databases as the objects to be synchronized.

    Note
    • If you select a database as the object to be synchronized, all schema changes in the database are synchronized to the destination database.
    • If you select a table as the object to be synchronized, only ADD COLUMN operations on the table are synchronized to the destination database.
    • After an object is synchronized to the destination database, the name of the object remains unchanged. You can change the name of an object in the destination cluster 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 Next.
  10. Specify a type for the tables to be synchronized to the destination database.
    Specify a table type
    Note After you select Initial Schema Synchronization, you must specify the type, primary key column, and partition key column for the tables to be synchronized to AnalyticDB for MySQL. For more information, see CREATE TABLE.
  11. 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.
  12. Close the Precheck dialog box after the following message is displayed: The precheck is passed.
  13. 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.