Synchronize a self-managed Oracle to Message Queue for Kafka

Prerequisites

• Ensure that a source self-managed Oracle database and a destination Alibaba Cloud Message Queue for Kafka instance are created.

  Note

  For information about the supported versions of the source database and destination instance, see Overview of data synchronization scenarios.

• The self-managed Oracle database must be in ARCHIVELOG mode. Also, set a reasonable retention period for archive logs and ensure they are accessible. For more information, see ARCHIVELOG.

• Supplemental logging enabled for the Oracle database, including SUPPLEMENTAL_LOG_DATA_PK and SUPPLEMENTAL_LOG_DATA_UI. For details, see Supplemental Logging.

• The available storage space in the destination Alibaba Cloud Message Queue for Kafka instance must exceed the storage space used by the source self-managed Oracle database.

• Create a topic in the destination Alibaba Cloud Message Queue for Kafka instance to receive the synchronized data. For more information, see Step 1: Create a topic.

• Before you perform data synchronization, understand the features and limitations of DTS when the source database is Oracle. You should also use Advanced Database & Application Migration (ADAM) to perform a database assessment to ensure a smooth migration. For more information, see Limitations and preparations for Oracle databases and Overview of database assessment.

Limitations

Billing

Single record size limit

The size of a single record written to Kafka cannot exceed 10 MB. If a row of data from the source exceeds this limit, DTS cannot write the record, and the task is interrupted. In this case, we recommend not synchronizing the table. If you must synchronize the table, configure the DTS task to exclude the columns that contain large fields. If a task is already running, remove the table from the synchronization object. Then, re-add the table and filter out the columns that contain large fields.

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 details on these topologies and their usage, see Synchronization topologies.

Supported SQL operations

Permissions required for the database account

Procedure

1. Go to the data synchronization task list page in the destination region. You can do this in one of two ways.

   DTS console

   1. Log on to the DTS console.

   2. In the navigation pane on the left, click Data Synchronization.

   3. In the upper-left corner of the page, select the region where the synchronization instance is located.

   DMS console

   Note

   The actual steps may vary depending on the mode and layout of the DMS console. For more information, see Simple mode console and Customize the layout and style of the DMS console.

   1. Log on to the DMS console.

   2. In the top menu bar, choose Data + AI > DTS (DTS) > Data Synchronization.

   3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.

2. Click Create Task to navigate to the task configuration page.

3. Configure the source and destination databases.

   Category	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 the location of your source database. This topic uses Self-managed Database on ECS as an example. Note If the source instance is a self-managed database, you must complete the required preparations. For more information, see Overview of preparations.
   	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 Number	Enter the service port of the self-managed Oracle database. The default value is 1521.
   	Oracle Type	Non-RAC Instance: If you select this option, you must also specify the SID. RAC or PDB Instance: If you select this option, you must also specify the Service Name. Important Data synchronization from Oracle RAC instances is not supported for this task. In this example, Non-RAC Instance is selected.
   	Database Account	Enter the database account of the self-managed Oracle database. For more information about the required permissions, see Permissions required for the database account.
   	Database Password	Enter the password for the specified database account.
   Destination Database	Database Type	Select Kafka.
   	Connection Type	Select Express Connect, VPN Gateway, or Smart Access Gateway. Note In this example, the Message Queue for Apache Kafka instance is treated as a self-managed database accessed through a private connection.
   	Instance Region	Select the region where the Message Queue for Apache Kafka instance is located.
   	Connected VPC	Select the VPC ID of the destination Message Queue for Apache Kafka instance. You can find the VPC ID on the Basic Information page of the Kafka instance.
   	Hostname or IP Address	Enter an IP address from the Default Endpoint section of the Message Queue for Apache Kafka instance. Note You can find the IP address of the Default Endpoint on the Basic Information page of the Message Queue for Apache Kafka instance.
   	Port Number	The service port of the Message Queue for Apache Kafka instance. The default value is 9092.
   	Database Account	Enter the database account of the Message Queue for Apache Kafka instance. Note If the Message Queue for Apache Kafka instance is a VPC-connected instance, you do not need to configure the Database Account and Database Password parameters.
   	Database Password	Enter the password for the specified database account.
   	Kafka Version	Select the version that corresponds to your Kafka instance.
   	Connection Method	Select Non-encrypted or SCRAM-SHA-256 based on your business and security requirements.
   	Topic	From the drop-down list, select the topic to which you want to send the data.
   	Use Kafka Schema Registry	Kafka Schema Registry is a metadata serving layer that provides a RESTful interface to store and retrieve Avro schemas. No: Do not use Kafka Schema Registry. Yes: Use Kafka Schema Registry. You must enter the URL or IP address registered in Kafka Schema Registry for your Avro schema.

4. After the configuration is complete, click Test Connectivity and Proceed at the bottom of the page. In the CIDR Blocks of DTS Servers dialog box, click Test Connectivity.

   Note

   Ensure that the IP address blocks of the DTS service are added to the security settings of the source and destination databases, either automatically or manually, to allow access from DTS servers. For more information, see Add the IP address whitelist of DTS servers.

5. Configure the task objects.

   1. On the Configure Objects page, specify the objects to synchronize.

      Parameter	Description
      Synchronization Type	DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.
      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 Database Table Column 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.
      Data Format in Kafka	Select the storage format for data synchronized to the Kafka instance based on your requirements. If you select DTS Avro, you need to parse the data based on the DTS Avro schema definition. For more information, see DTS Avro schema definition and DTS Avro deserialization example. If you select SharePlex JSON, see SharePlex JSON for parameter descriptions and examples.
      Kafka Data Compression Format	Select the compression format for Kafka messages based on your requirements. LZ4 (Default): Lower compression ratio, faster compression speed. GZIP: Higher compression ratio, slower compression speed. Note This format consumes more CPU resources. Snappy: Moderate compression ratio and speed.
      Policy for Shipping Data to Kafka Partitions	Select a policy based on your business requirements.
      Message acknowledgement mechanism	Select a message acknowledgment mechanism based on your business requirements.
      Topic That Stores DDL Information	From the drop-down list, select the topic to store DDL information. Note If you do not select a topic, DDL information is stored by default in the topic that receives the data.
      Capitalization of Object Names in Destination Instance	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 objects at the database, table, or column level. If you select only tables or columns, DTS does not synchronize other object types (such as views, triggers, and stored procedures).
      Selected Objects	No additional configuration is required for this example. You can use the mapping feature to set the topic name, number of partitions, and partition key for the source table in the destination Kafka instance. For more information, see Mapping information. Note If you use the object name mapping feature, other objects that depend on the mapped object may fail to be synchronized. To select the SQL operations for incremental data synchronization, right-click the synchronization object in the Selected Objects box and select the desired SQL operations in the dialog box that appears.

   2. Click Next: 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 requirements. This parameter is optional.
      Actual Write Code	Select the encoding used to write data to the destination based on your 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 contact. 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. Purchase the instance.

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

   2. 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.

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

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

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

Mapping information

1. In the Selected Objects area, hover over the destination topic name.

2. Click Edit next to the destination topic name.

3. In the Edit Table dialog box, configure the mapping information.

   Note

   • The dialog box is named Edit Schema at the database level and Edit Table at the table level. The Edit Schema dialog box supports fewer parameters.

   • If you are not synchronizing an entire database, you cannot modify the Name of target Topic and Number of Partitions parameters in the Edit Schema dialog box.

   Parameter	Description
   Name of target Topic	The name of the destination topic that receives data from the source table. By default, this is the Topic selected in the Destination Database section of the Configurations for Source and Destination Databases step. Important If the destination database is a Message Queue for Apache Kafka instance, the topic name you enter must already exist in the destination Kafka instance. Otherwise, the data synchronization will fail. If the destination database is a self-managed Kafka database and the synchronization task includes database and table structure, Data Transmission Service (DTS) attempts to create the specified topic in the destination database. If you modify the Name of target Topic, the system writes data to the newly specified topic.
   Filter Conditions	For details, see Set filter conditions.
   Number of Partitions	The number of partitions for the destination topic.
   Partition Key	You can configure this parameter when Policy for Shipping Data to Kafka Partitions is set to Ship Data to Separate Partitions Based on Hash Values of Primary Keys. You can specify one or more columns as the partition key. Data Transmission Service (DTS) calculates a hash value based on the specified key and uses this value to distribute rows across the partitions of the destination topic. Note You can configure the Partition Key only in the Edit Table dialog box.

4. Click OK.

FAQ

Can I change the Kafka Data Compression Format or Message acknowledgement mechanism after the task is created?

Yes. Modify these settings through the object modification feature. See Modify the objects to be synchronized.