AnalyticDB for MySQL is a real-time online analytical processing (RT-OLAP) service that is 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 a DRDS instance to an AnalyticDB for MySQL cluster by using Data Transmission Service (DTS). After you synchronize data, you can use AnalyticDB for MySQL to build internal business intelligence (BI) systems, interactive query systems, and real-time report systems.

Prerequisites

  • A database is created in the DRDS instance based on one or more ApsaraDB RDS for MySQL instances.
  • 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.

Precautions

  • DTS uses read and write resources of the source and destination databases during initial full data synchronization. This may increase the loads of the database servers. 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 impact of data synchronization on 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 utilization of the source and destination databases is less than 30%.
  • We recommend that you do not scale up or down the DRDS instance, migrate frequently-accessed tables, change shard keys, or perform DDL operations on objects during data synchronization. Otherwise, data synchronization may fail.
  • If you need to change the network type of a DRDS instance during data synchronization, you must submit a ticket to modify the network connection information.
  • We recommend that you do not use gh-ost or pt-online-schema-change to perform data definition language (DDL) operations on the required objects during data synchronization. Otherwise, data may fail to be synchronized.
  • Due to the limits of AnalyticDB for MySQL, if the disk space usage of the 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 that you want to synchronize. You must ensure that the destination cluster has sufficient storage space.
  • Prefix indexes cannot be synchronized. If the source database contains prefix indexes, data may fail to be synchronized.

SQL operations that can be synchronized

INSERT, UPDATE, and DELETE

Permissions required for database accounts

Database Required permissions
DRDS The SELECT permission on the objects to be synchronized, the REPLICATION CLIENT permission, and the REPLICATION SLAVE permission. These permissions are automatically granted by DTS.
AnalyticDB for MySQL The read and write permissions on the objects to be synchronized.

Data type mappings

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

Procedure

  1. Purchase a data synchronization instance. For more information, see Purchase a DTS instance.
    Note On the buy page, set Source Instance to PolarDB-X, set Target Instance to AnalyticDB for MySQL, 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 This parameter is set to DRDS Instance and cannot be changed.
    Instance Region The source region that you selected on the buy page. You cannot change the value of this parameter.
    DRDS Instance ID Select the ID of the source DRDS instance.
    Destination Instance Details Instance Type This parameter is set to AnalyticDB and cannot be changed.
    Instance Region The destination region that you selected on the buy page. You cannot change the value of this parameter.
    Version Select 3.0.
    Database Select the ID of the AnalyticDB for MySQL cluster.
    Database Account Enter the database account of the AnalyticDB for MySQL cluster. For information about the permissions that are required for the account, see Permissions required for database accounts.
    Database Password Enter the password of the database account.
  7. In the lower-right corner of the page, click Set Whitelist and Next.
    Note In this step, DTS adds the CIDR blocks of DTS servers to the whitelists of the source DRDS instance and the destination AnalyticDB for MySQL cluster. This ensures that DTS servers can connect to the source instance and the destination cluster.
  8. Select the synchronization policy and the objects to be synchronized.
    Select the synchronization policy and the objects to be synchronized
    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 source and destination databases do not contain identical table names, the precheck is passed. Otherwise, an error is returned during precheck and the data synchronization task cannot be started.
      Note You can use the object name mapping feature to rename the tables that are synchronized to the destination database. You can use this feature if the source and destination databases contain identical table names and the tables in the destination database cannot be deleted or renamed. 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 specific 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.
    • No is selected by default.
    Note You can merge the data source columns based on tasks rather than tables. To merge only the data source columns of specific 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.
    • Insert
    • Update
    • Delete
    Select the objects to be synchronized

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

    Note
  9. In the lower-right corner of the page, click Next.
  10. Specify a type for the tables that you want to synchronize 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 that you want to synchronize 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, 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.
  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.