Create a data subscription

Source database requirements

Other limits

Limit	Details
DDL tracking	To track schema updates, create a trigger and a function in the source database to capture DDL information. For more information, see Use triggers and functions to implement incremental DDL migration for PostgreSQL databases.
Heartbeat table	DTS adds a heartbeat table named dts_postgres_heartbeat to the source database to maintain accurate latency metrics.
Replication slot management	DTS creates a replication slot prefixed with dts_sync_ for the source database. DTS clears historical replication slots every 90 minutes. If the task is released or fails, DTS clears the replication slot automatically. If a primary/secondary switchover is performed, log on to the secondary database to clear the replication slot manually.
Single database per task	A single change tracking task tracks data from only one database. Create a separate task for each database.
FLOAT and DOUBLE precision	DTS uses the ROUND(COLUMN,PRECISION) function to retrieve values from FLOAT and DOUBLE columns. The default precision is 38 digits for FLOAT and 308 digits for DOUBLE. Verify that these defaults meet your business requirements.

Step 1: Go to the Change Tracking Tasks page

1. Log on to the .

2. In the top navigation bar, move the pointer over Data + AI.

3. Choose DTS (DTS) > Change Tracking.

The navigation steps may vary depending on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console. You can also go directly to the Change Tracking page of the new DTS console.

Step 2: Configure the source database

1. Click Create Task.

2. (Optional) In the upper-right corner of the page, click New Configuration Page.

   Skip this step if the Back to Previous Version button is already displayed. The new configuration page is recommended when available.

3. Read the Limits displayed at the top of the page before specifying the source database instance.

4. Configure the source database and consumer network settings:

   Section	Parameter	Description
   (None)	Task Name	A name for the change tracking task. DTS assigns a default name. Specify a descriptive name to identify the task more easily. The name does not need to be unique.
   Source Database	Select an existing database connection	Select an existing instance to reuse its settings, or leave blank to configure the database manually.
   	Database Type	Select PostgreSQL.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	The region where the source ApsaraDB RDS for PostgreSQL instance resides.
   	Instance ID	The ID of the source instance.
   	Database Name	The name of the source database.
   	Database Account	The privileged account for the source database. The account must be the owner of the database. For more information about creating accounts and granting permissions, see Create an account and Create a database.
   	Database Password	The password for the database account.
   Consumer Network Type	Network Type	Fixed to VPC. Select a VPC and a vSwitch. This setting cannot be changed after the task is configured. If the change tracking client is deployed in a VPC, select the same VPC and vSwitch as the client to minimize network latency. For more information, see VPCs.

5. Click Test Connectivity and Proceed. DTS automatically adds its CIDR blocks to the security settings of Alibaba Cloud database instances and ECS-hosted databases. For self-managed databases in data centers or third-party clouds, manually add the DTS CIDR blocks to the database security settings. For more information, see Add the CIDR blocks of DTS servers.

   Warning

   Adding DTS CIDR blocks to instance whitelists or ECS security group rules may introduce security risks. Before proceeding, take preventive measures such as: using strong credentials, restricting exposed ports, authenticating API calls, auditing whitelist rules regularly, or connecting through Express Connect, VPN Gateway, or Smart Access Gateway.

Step 3: Select objects and configure advanced settings

Configure the following settings under Basic Settings and Advanced Settings:

Basic settings

Parameter	Description
Data Change Types	Select the types of changes to track: Data Update tracks INSERT, DELETE, and UPDATE operations. Schema Update tracks create, delete, and modify operations on all object schemas. Use the change tracking client to filter tracked data. If you select Schema Update, create a trigger and a function in the source database first. For more information, see Use triggers and functions to implement incremental DDL migration for PostgreSQL databases.
Source Objects	Select tables or databases from the Source Objects section, then click the icon to add them to the Selected Objects section. If you select a database, DTS tracks all objects in the database, including new objects added after the task starts. If you select a table, DTS tracks only that table. To add more tables later, see Modify the objects for change tracking.

Advanced settings

Step 4: Run the precheck

1. Click Next: Save Task Settings and Precheck. To preview the API parameters used to configure this task, hover over the button and click Preview OpenAPI parameters.

2. Wait for the precheck to complete. The task can start only after passing the precheck.

   • If a check item fails, click View Details next to the item, fix the issue, and click Precheck Again.

   • If a check item shows an alert that can be ignored, click Confirm Alert Details, click Ignore in the dialog box, click OK, and then click Precheck Again. Ignoring alert items may cause data inconsistency.

3. When Success Rate reaches 100%, click Next: Purchase Instance.

Step 5: Purchase the instance

On the Purchase page, configure the billing settings:

1. Read and select Data Transmission Service (Pay-as-you-go) Service Terms.

2. Click Buy and Start. The task appears in the task list with its current progress.