Data Transmission Service:Synchronize data from a PolarDB-X 1.0 instance to an AnalyticDB for PostgreSQL instance

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 or specifications are unfavorable, 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%.
• When the data synchronization task is running, do not upgrade or downgrade the PolarDB-X instance, migrate frequently-accessed tables, change shard keys, or perform DDL operations on source objects. Otherwise, the data synchronization task fails.
• If you need to change the network type of a PolarDB-X instance during data synchronization, you must modify the network connection information of the data synchronization task after you complete the network type change.
• After a data synchronization task is started, new tables that are created in the source database can be synchronized. To do this, you must add the tables to the selected objects of the task. For more information, see Add an object to a data synchronization task.

Limits

• Only tables can be selected as the objects to synchronize.
• DTS does not synchronize the following types of data: JSON, GEOMETRY, CURVE, SURFACE, MULTIPOINT, MULTILINESTRING, MULTIPOLYGON, and GEOMETRYCOLLECTION.

SQL operations that can be synchronized

INSERT, UPDATE, and DELETE

Term mappings

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 PostgreSQL, and set Synchronization Topology to One-Way Synchronization.
2. Log on to the DTS console.
   Note If you are redirected to the Data Management (DMS) console, you can click the icon in the lower-right corner to go to the previous version of the DTS console.
3. In the left-side navigation pane, click Data Synchronization.
4. In the upper part of the Data Synchronization Tasks page, select the region in which the destination instance resides.
5. Find the data synchronization instance and click Configure Task in the Actions column.
6. Configure the source and destination instances.
   

   Section	Parameter	Description
   N/A	Synchronization Task Name	The task name that DTS automatically generates. We recommend that you specify a descriptive name that makes it easy to identify the task. 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	The ID of the source PolarDB-X instance.
   Destination Instance Details	Instance Type	This parameter is set to AnalyticDB for PostgreSQL and cannot be changed.
   	Instance Region	The destination region that you selected on the buy page. The value of this parameter cannot be changed.
   	Instance ID	The ID of the AnalyticDB for PostgreSQL instance.
   	Database Name	The name of the destination database in the AnalyticDB for PostgreSQL instance.
   	Database Account	The database account of the AnalyticDB for PostgreSQL instance.
   	Database Password	The password of the database account.

7. In the lower-right corner of the page, click Set Whitelist and Next.
   Note

   • You do not need to modify the security settings for ApsaraDB instances (such as ApsaraDB RDS for MySQL and ApsaraDB for MongoDB) and ECS-hosted databases. DTS automatically adds the CIDR blocks of DTS servers to the whitelists of ApsaraDB instances or the security group rules of Elastic Compute Service (ECS) instances. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
   • After data synchronization is complete, we recommend that you remove the CIDR blocks of DTS servers from the whitelists or security groups.
8. Set the synchronization policy and objects to synchronize.
   

   Setting	Parameter	Description
   Set the synchronization policy	Initial Synchronization	The synchronization policy. In most cases, you must select both Initial Schema Synchronization and Initial Full Data Synchronization. After the precheck is complete, DTS synchronizes the schemas and data of 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 check for empty destination tables during the precheck. Clears the data in destination tables before initial full data synchronization. If you want to synchronize your business data after you test the data synchronization task, you can select this mode. Ignore Skips the check for empty destination tables during the precheck. Synchronizes data to the destination tables without clearing the tables during initial full data synchronization. If you want to synchronize data from multiple tables to a single table, you can select this mode.
   	Synchronization Type	The operations that you want to synchronize based on your business requirements. Insert Update Delete
   Select the objects to synchronize	None	Select one or more tables from the Available section and click the icon to add the tables to the Selected section. Note You can select only tables as the objects to synchronize. You can use the object name mapping feature to rename the columns that are synchronized to the destination database. For more information, see Rename an object to be synchronized.
   Rename Databases and Tables	None	You can use the object name mapping feature to rename the objects that are synchronized to the destination instance. For more information, see Object name mapping.
   Retry Time for Failed Connections	None	By default, if DTS fails to connect to the source or destination database, DTS retries within the next 720 minutes (12 hours). You can specify the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Note When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.

9. In the lower-right corner of the page, click Next.
10. Specify the primary key columns and distribution columns of the tables 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 in Step 8. For more information about primary key columns and distribution columns, see Define constraints and Define table distribution.
11. In the lower-right corner of the page, click Precheck.
    Note

    • Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization task only after the task passes the precheck.
    • If the task fails to pass the precheck, click the icon next to each failed item to view details.
      • After you troubleshoot the issues based on the causes, run a precheck again.
      • If you do not need to troubleshoot the issues, ignore failed items and run a precheck again.
12. Close the Precheck dialog box after the following message is displayed: Precheck Passed. Then, the data synchronization task starts.
13. Wait until initial synchronization is complete and the data synchronization task enters the Synchronizing state.
    You can view the status of the data synchronization task on the Synchronization Tasks page.