From PostgreSQL to Kafka

Supported Source and Destination Databases

Supported Synchronization Objects

Database Account Permission Requirements

Suggestions

• The success of database synchronization depends on environment and manual operations. To ensure a smooth synchronization, perform a synchronization trial before you start the synchronization to help you detect and resolve problems in advance.
• It is recommended that you start a task during off-peak hours to minimize the impact of synchronization on your services.

Precautions

Prerequisites

• You have logged in to the DRS console.

• You have read Suggestions and Precautions.

Procedure

1. On the Data Synchronization Management page, click Create Synchronization Task.
2. On the Create Synchronization Instance page, specify the task name, description, and the synchronization instance details, and click Create Now.
   • Task information description

     Table 5 Task information

     Parameter	Description
     Task Name	The task name must start with a letter and consist of 4 to 50 characters. It can contain only letters, digits, hyphens (-), and underscores (_).
     Description	The description consists of a maximum of 256 characters and cannot contain special characters !=<>'&"\

   • Synchronization instance details

     Table 6 Synchronization instance settings

     Parameter	Description
     Data Flow	Select Out of the cloud.
     Source DB Engine	Select PostgreSQL.
     Destination DB Engine	Select Kafka.
     Network Type	Public network is used as an example. Available options: Public network and VPN or Direct Connect Public network is suitable for data synchronization from on-premises or external cloud databases to the destination databases bound with an EIP. VPN or Direct Connect is suitable for data synchronization from on-premises databases to cloud databases, or between databases across regions on the cloud using a VPN, Direct Connect, Cloud Connect, VPCEP, or a VPC peering connection.
     Source DB Instance	Specifies an RDS PostgreSQL DB instance you have created.
     Synchronization Mode	Incremental Through log parsing, incremental data generated on the source database is synchronized to the destination database. During synchronization, the source database continues to provide services for external systems with zero downtime.
     Specify EIP	This parameter is available when you select Public network for Network Type. Select an EIP to be bound to the DRS instance. DRS will automatically bind the specified EIP to the DRS instance and unbind the EIP after the task is complete. The number of specified EIPs must be the consistent with that of DB instances.

   • Task type

     Table 7 Task type information

     Parameter	Description
     Specifications	DRS instance specifications. Different specifications have different performance upper limits. For details, see Real-Time Synchronization.
     AZ	Select the AZ where you want to create the DRS task. Selecting the one housing the source or destination database can provide better performance.

   • Enterprise Project and Tags

     Table 8 Enterprise Project and Tags

     Parameter	Description
     Enterprise Project	An enterprise project you would like to use to centrally manage your cloud resources and members. Select an enterprise project from the drop-down list. The default project is default.
     Tags	Tags a task. This configuration is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 20 tags. After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.

   Note

   If a task fails to be created, DRS retains the task for three days by default. After three days, the task automatically stops.

3. On the Configure Source and Destination Databases page, wait until the synchronization instance is created. Then, specify source and destination database information and click Test Connection for both the source and destination databases to check whether they have been connected to the synchronization instance. After the connection tests are successful, click Next.

   Table 9 Source database settings

   Parameter	Description
   DB Instance Name	The RDS for PostgreSQL instance selected when you created the migration task. The instance cannot be changed.
   Database Username	The username for accessing the source database.
   Database Password	The password for the database username.

   Note

   The username and password of the source database are encrypted and stored in DRS and will be cleared after the task is deleted.

   Table 10 Destination database settings

   Parameter	Description
   IP Address or Domain Name	IP address or domain name of the destination database in the IP address/Domain name:Port format. The port of the destination database. Range: 1 - 65535 You can enter up to 10 groups of IP addresses or domain names of the destination database. Separate multiple values with commas (,). For example: 192.168.0.1:8080,192.168.0.2:8080.
   Method	Available options: PLAINTEXT, SSL, SASL_PLAINTEXT, and SASL_SSL. For details, see Kafka Authentication.

4. On the Set Synchronization Task page, select the synchronization policy, objects, and data format, and click Next.

   Table 11 Synchronization object

   Parameter	Description
   Synchronize DML	Select the DML operations to be synchronized. By default, all DML operations are selected. If you do not select Delete, DELETE statements in the incremental data of the source database will not be synchronized, which may cause a data inconsistency. As a result, there may be a data conflict or the task may fail.
   Source Database Replication Slot Name	You can choose whether to specify the replication slot of the source database. After replication slot is enabled, enter the replication slot name. The name contains 63 characters and cannot start with a digit. Only lowercase letters, digits, and underscores (_) are allowed.
   Topic Synchronization Policy	Topic synchronization policy. You can select A specific topic or Auto-generated topics.
   Topic	Select the topic to be synchronized to the destination database. This parameter is available when the topic is set to A specified topic.
   Topic Name Format	This parameter is available when Topic Synchronization Policy is set to Auto-generated topics. Due to Kafka restrictions, a topic name can contain only ASCII characters, periods (.), underscores (_), and hyphens (-). If a topic name exceeds the limit, the topic fails to be created and the task is abnormal. If a topic name contains a database object name, ensure that the characters in the object name meet the Kafka topic naming requirements.
   Number of Partitions	This parameter is available when Topic Synchronization Policy is set to Auto-generated topics. The number of partitions of a topic. Each topic can have multiple partitions. More partitions can provide higher throughput but consume more resources. Set the number of partitions based on the actual situation of brokers.
   Replication Factor	This parameter is available when Topic Synchronization Policy is set to Auto-generated topics. Number of copies of a topic. Each topic can have multiple copies, and the copies are placed on different brokers in a cluster. The number of copies cannot exceed the number of brokers. Otherwise, the topic fails to be created.
   Synchronize Topic To	The policy for synchronizing topics to the Kafka partitions. If topics are synchronized to different partitions by hash value of the database, schema and table names, the performance on a single table query can be improved. If topics are synchronized to different partitions by hash value of the primary key, one table corresponds to one topic. This prevents data from being written to the same partition, and consumers can obtain data from different partitions concurrently. For a table without a primary key, if you select Partitions are identified by the hash values of the primary key, topics are synchronized to different partitions based on the hash value of the database_name.schema.table_name. Partitions are differentiated by the hash values of database_name.schema_name: This mode applies to scenarios where one database corresponds to one topic, preventing multiple schemas from being written to the same partition, so that consumers can obtain data from different partitions concurrently. If topics are synchronized to partition 0, strong consistency can be obtained but write performance is impacted.
   Data Format in Kafka	Select the data format to be delivered to Kafka. Avro: A binary encoded format that is efficient. You need to deserialize the data later. JSON: JSON message format, which is easy to interpret but takes up more space. For details, see Kafka Message Format.
   Synchronization Object	The left pane displays the source database objects, and the right pane displays the selected objects. DRS supports table- and database-level synchronization. You can select data for synchronization based on your service requirements. NOTE: To quickly select the desired database objects, you can use the search function. If there are changes made to the source databases or objects, click in the upper right corner to update the objects to be synchronized. If an object name contains spaces, the spaces before and after the object name are not displayed. If there are two or more consecutive spaces in the middle of the object name, only one space is displayed. The name of the selected synchronization object cannot contain spaces.

5. On the Check Task page, check the synchronization task.
   • If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
   • If all check items are successful, click Next.
     Note

     You can proceed to the next step only when all checks are successful. If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.

6. On the displayed page, specify Start Time, Send Notifications, SMN Topic, Delay Threshold (s), and Stop Abnormal Tasks After, confirm that the configured information is correct, and click Submit to submit the task.

   Table 12 Task startup settings

   Parameter	Description
   Start Time	Set Start Time to Start upon task creation or Start at a specified time based on site requirements. NOTE: After a synchronization task is started, the performance of the source and destination databases may be affected. You are advised to start a synchronization task during off-peak hours.
   Send Notifications	This parameter is optional. If the status, latency metric, or data of the migration task is abnormal, DRS will send you a notification.
   SMN Topic	This parameter is available only after you enable Send Notifications and create a topic on the SMN console and add a subscriber.

7. After the task is submitted, you can view and manage it on the Data Synchronization Management page.
   • You can view the task status. For more information about task status, see Task Statuses.
   • You can click in the upper right corner to view the latest task status.
   • By default, DRS retains a task in the Configuration state for three days. After three days, DRS automatically deletes background resources, but the task status remains unchanged. When you configure the task again, DRS applies for resources for the task again. In this case, the IP address of the DRS instance changes.
   • For a public network task, DRS needs to delete background resources after you stop the task. The EIP bound to the task cannot be restored to the Unbound state until background resources are deleted.