Data Transmission Service:Synchronize self-managed Oracle to DataHub

Prerequisites

• A source self-managed Oracle database of version 19c, 18c, 12c, 11g, 10g, or 9i and a target DataHub instance have been created.

• The self-managed Oracle database runs in ARCHIVELOG mode, and its archived logs have a reasonable retention period and are accessible. For more information, see ARCHIVELOG.

• Supplemental logging, including supplemental_log_data_pk and supplemental_log_data_ui, is enabled. For more information, see Supplemental Logging.

• You have activated the DataHub service and created a project to receive the synchronized data. For details, see Quick start (synchronization example) and Project operations.

• Before you synchronize an Oracle source database, understand the capabilities and limitations of Data Transmission Service (DTS) and use Advanced Database & Application Migration (ADAM) to assess your database. This ensures a smooth migration to the cloud. For more information, see Limitations and preparation for Oracle databases and Database assessment overview.

Limitations

Billing

Synchronization topologies

• One-way one-to-one synchronization

• One-way one-to-many synchronization

• One-way many-to-one synchronization

• One-way cascade synchronization

For more information, see Synchronization topologies.

Supported SQL operations

Database account permissions

Procedure

1. Go to the Data Synchronization Tasks page.

   1. Log on to the Data Management (DMS) console.

   2. In the top navigation bar, click Data + AI.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.

   Note

   • Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode console and Customize DMS console layout and style.

   • You can also go to the Data Synchronization Tasks page of the new DTS console.

2. Click Create Task and configure the source and destination databases.

   Section	Parameter	Description
   N/A	Task Name	DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.
   Source Database	Database Type	Select Oracle.
   	Connection Type	Select a connection method based on where the source database is deployed. This topic uses Self-managed Database on ECS as an example. Note If the source instance is a self-managed database, you must also complete the required preparations. For more information, see Preparation overview.
   	Instance Region	Select the region where the self-managed Oracle database is located.
   	ECS Instance ID	Select the ID of the ECS instance that hosts the self-managed Oracle database.
   	Port	Enter the service port of the self-managed Oracle database. The default value is 1521.
   	Oracle Type	This example uses RAC or PDB Instance. Non-RAC Instance: If you select this option, you must also enter the SID. RAC or PDB Instance: If you select this option, you must also enter the Service Name.
   	Database Account	Enter the account for the source self-managed Oracle database.
   	Database Password	Enter the password for the specified database account.
   Destination Database	Database Type	Select DataHub.
   	Connection Type	Select Alibaba Cloud Instance.
   	Instance Region	Select the region where the destination DataHub project is located.
   	Project	Select the DataHub Project.

3. In the lower part of the page, click Test Connectivity and Proceed.

   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 whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must ensure that the ECS instance can access the database. If the source or destination database is a self-managed database that is 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 whitelist of the database to allow DTS to access the database. For more information, see Whitelist DTS server IP addresses.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

4. Configure the synchronization objects and advanced settings.

   Parameter	Description
   Synchronization Type	Incremental Data Synchronization is selected and cannot be changed. By default, Schema Synchronization is also selected. After the precheck is complete, DTS initializes the full data of the synchronization objects from the source instance in the target cluster. This data serves as the baseline for subsequent incremental synchronization.
   Naming Rules of Additional Columns	When DTS synchronizes data to DataHub, it adds additional columns to the destination topic. If the names of the additional columns conflict with the names of existing columns in the destination topic, the data synchronization task fails. Set Naming Rules of Additional Columns to New Rule or Previous Rule based on your business requirements. Warning Before you select a naming rule, check for potential name conflicts between the additional columns and existing columns in the destination topic. Conflicts can cause task failures or data loss. For more information about the rules and definitions of additional columns, see Additional column names and definitions.
   Processing Mode for Existing Destination Tables	Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful. Note If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Object name mapping. Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example: If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database: During full data synchronization, DTS retains the destination record and skips the source record. During incremental synchronization, DTS overwrites the destination record with the source record. If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.
   Case Policy for Destination Object Names	Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.
   Source Objects	In the Source Objects box, click the objects, and then click to move them to the Selected Objects box. Note You can select tables as the synchronization objects.
   Selected Objects	To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name. To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk. Note You cannot set filter conditions if you select an entire database as the synchronization object. If you select tables as synchronization objects and need to use WHERE clauses to filter data, right-click a table in the Selected Objects box and specify the filter conditions in the dialog box that appears. For more information, see Set filter conditions. If you select tables as synchronization objects, you can set a shard key (a key used for partitioning) by right-clicking a table in the Selected Objects box and clearing the Sync All Columns check box in the dialog box that appears. Database name mapping is not supported. If you use object name mapping for a table or column, synchronization of other objects that depend on it may fail.

5. Click Next: Advanced Settings to proceed to the advanced settings.

   Parameter	Description
   Dedicated Cluster for Task Scheduling	By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.
   Retry Time for Failed Connections	If the connection to the source or destination database fails after the synchronization task starts, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails. Note If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances. DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.
   Retry Time for Other Issues	If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than that of Retry Time for Failed Connections.
   Enable Throttling for Full Data Synchronization	During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s). Note This parameter is available only if Synchronization Types is set to Full Data Synchronization. You can also adjust the rate of full data synchronization when the synchronization instance is running.
   Enable Throttling for Incremental Data Synchronization	You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).
   Environment Tag	You can select an environment tag to identify the instance based on your business requirements. In this example, no selection is required.
   Actual Write Code	You can select the character set for writing data to the destination based on your business requirements.
   Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
   Monitoring and Alerting	Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts. No: No alerts are configured. Yes: Configures alerts. You must also set the alert threshold and alert notifications. For more information, see Configure monitoring and alerting during task configuration.

6. Save the task and perform a precheck.

   • To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.

   • If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

   Note

   • Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.

   • If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.

   • If the precheck generates warnings:

     • For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.

     • For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.

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

8. On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

   Category	Parameter	Description
   New Instance Class	Billing Method	Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks. Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.
   	Resource Group Settings	The resource group to which the instance belongs. The default is default resource group. For more information, see What is resource management?.
   	Instance Class	DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.
   	Subscription Duration	In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years. Note This option appears only when the billing method is Subscription.

9. Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.

10. Click Buy and Start, and then click OK in the OK dialog box.

    You can monitor the task progress on the data synchronization page.