PolarDB:Synchronize data from a self-managed MySQL database hosted on ECS to a PolarDB for MySQL cluster

Step 1: Purchase a DTS instance

Purchase a DTS instance. On the purchase page, set:

• Source Instance: MySQL

• Destination Instance: PolarDB

• Synchronization Topology: One-way Synchronization

Step 2: Configure source and destination databases

1. Log on to the DTS console.

   If you are redirected to the Data Management (DMS) console, click the icon in the to return to the previous version of the DTS console.

2. In the left-side navigation pane, click Data Synchronization.

3. At the top of the Synchronization Tasks page, select the region where the destination instance resides.

4. Find the synchronization instance and click Configure Task in the Actions column.

5. Configure the source and destination databases using the following parameters.

   Source database

   Parameter	Description
   Task Name	A descriptive name for the task. Does not need to be unique.
   Instance Type	Select User-Created Database in ECS Instance.
   Instance Region	The source region you selected on the purchase page. Read-only.
   ECS Instance ID	The ID of the ECS instance that hosts the self-managed MySQL database.
   Database Type	Set to MySQL. Read-only.
   Port Number	The port number of the self-managed MySQL database.
   Database Account	The account with the required permissions listed in the Prerequisites.
   Database Password	The password for the database account.

   Destination database

   Parameter	Description
   Instance Type	Set to PolarDB Instance. Read-only.
   Instance Region	The destination region you selected on the purchase page. Read-only.
   PolarDB Instance ID	The ID of the destination PolarDB for MySQL cluster.
   Database Account	The account with read and write permissions on the objects to be synchronized.
   Database Password	The password for the database account.

Step 3: Configure the whitelist

Click Set Whitelist and Next in the lower-right corner.

• If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the IP address whitelist of the instance.

• If the source or destination database is a self-managed database hosted on an ECS instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance. If the database is hosted across multiple ECS instances, manually add the DTS CIDR blocks to the security group rules of each instance.

• If the source or destination database is a self-managed database deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the IP address whitelist of the database.

For more information, see Add the CIDR blocks of DTS servers.

Step 4: Select objects and configure conflict handling

Configure the following settings, then click Next.

Setting	Description
Processing mode for existing target tables	Pre-check and Intercept (default): DTS checks whether the destination cluster has tables with the same names as the source. The task fails precheck if conflicts are found. Use the object name mapping feature to resolve naming conflicts without deleting destination tables.<br><br>Ignore: Skips the name conflict check. During initial synchronization, DTS skips records that share primary keys with existing destination records. During incremental synchronization, DTS does write those records. If schemas differ between source and destination, the task may fail or synchronize only partial data.
Objects to synchronize	Select tables or databases from the Available section and click to move them to the Selected section. Selecting a database synchronizes all schema changes within that database to the destination cluster.
Rename databases and tables	Use object name mapping to rename objects in the destination cluster.
Source table DMS_ ONLINE_ Do you want to copy the temporary table to the target database during DDL	If you use Data Management (DMS) to run online DDL operations on the source database, choose whether to synchronize the temporary tables generated by those operations.<br><br>Yes: Synchronizes temporary table data. Large online DDL operations may increase synchronization latency.<br><br>No: Skips temporary tables and synchronizes only the original DDL. Destination tables may be temporarily locked.
Retry time for failed connections	Default is 720 minutes (12 hours). If DTS reconnects within this window, the task resumes automatically. If the retry window expires without reconnection, the task fails. DTS charges apply while retries are in progress.

Step 5: Select initial synchronization types

Select the synchronization types to include.

Selecting both Initial Schema Synchronization and Initial Full Data Synchronization causes DTS to replicate existing schemas and data before switching to incremental synchronization.

Step 6: Run the precheck and start synchronization

1. Click Precheck in the lower-right corner.

2. If the precheck fails, click the icon next to each failed item to view details. Fix the issues and run the precheck again. If you do not need to fix an issue, ignore the failed item and start a new precheck.

3. After the Precheck Passed message appears, close the Precheck dialog box. The synchronization task starts automatically.

4. On the Synchronization Tasks page, monitor the task status. Wait until initial synchronization is complete and the task enters the Synchronizing state.