From GaussDB(for MySQL) to Kafka

Supported Source and Destination Databases

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.
  • If network bandwidth is not limited, the query rate of the source database increases by about 50 MB/s during full synchronization, and two to four CPUs are occupied.
  • Tables to be synchronized without a primary key may be locked for 3s.
  • When DRS concurrently reads data from a database, it will use about 6 to 10 sessions. The impact of the connections on services must be considered.
  • If you read a table, especially a large table, during the full synchronization, the exclusive lock on that table may be blocked.

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 3 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 4 Synchronization instance settings

     Parameter	Description
     Data Flow	Select Out of the cloud.
     Source DB Engine	Select GaussDB(for MySQL).
     Destination DB Engine	Select Kafka.
     Network Type	The Public network is used as an example. Available options: VPC, Public network, and VPN or Direct Connect VPC is suitable for data synchronization between cloud databases of the same account in the same region and VPC. 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, between databases of different accounts in the same region on the cloud, or between databases across regions on the cloud using a VPN, Direct Connect, Cloud Connect, VPCEP, or a VPC peering connection.
     Source DB Instance	The GaussDB(for MySQL) instance you created.
     Synchronization Instance Subnet	Select the subnet where the synchronization instance is located. You can also click View Subnets to go to the network console to view the subnet where the instance resides. By default, the DRS instance and the destination DB instance are in the same subnet. You need to select the subnet where the DRS instance resides, and there are available IP addresses for the subnet. To ensure that the synchronization instance is successfully created, only subnets with DHCP enabled are displayed.
     Synchronization Mode	Available options: Full+Incremental and Incremental Full+Incremental This synchronization mode allows you to synchronize data in real time. After a full synchronization initializes the destination database, an incremental synchronization parses logs to ensure data consistency between the source and destination databases. NOTE: If you select Full+Incremental, data generated during the full synchronization will be continuously synchronized to the destination database, and the source remains accessible. Incremental Through log parsing, incremental data generated on the source database is synchronized to the destination database.
     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 5 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 6 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, select the check box before the agreement and click Next.

   Table 7 Source database settings

   Parameter	Description
   DB Instance Name	The GaussDB(for MySQL) instance you selected when creating the task. This parameter 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 8 Destination database settings

   Parameter	Description
   IP Address or Domain Name	The IP address or domain name of the destination database.
   Security Protocol	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 9 Synchronization Object

   Parameter	Description
   Flow Control	You can choose whether to control the flow. Flow Control takes effect in the full phase only. Yes You can customize the maximum synchronization speed. During the full synchronization, the synchronization speed of each task (or each subtask in multi-task mode) does not exceed the value of this parameter. In addition, you can set the time range based on your service requirements. The traffic rate setting usually includes setting of a rate limiting time period and a traffic rate value. Flow can be controlled all day or during specific time ranges. The default value is Always. A maximum of 10 time ranges can be set, and they cannot overlap. The flow rate must be set based on the service scenario and cannot exceed 9,999 MB/s. No The synchronization speed is not limited and the outbound bandwidth of the source database is maximally used, which will increase the read burden on the source database. For example, if the outbound bandwidth of the source database is 100 MB/s and 80% bandwidth is used, the I/O consumption on the source database is 80 MB/s. NOTE: The flow control mode takes effect only in the full synchronization phase. You can also change the flow control mode after creating a task. For details, see Modifying the Flow Control Mode.
   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.
   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 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.
   Data Format in Kafka	Select the data format to be delivered from GaussDB(for MySQL) to Kafka. Avro refers to binary encoded format. This option is available only when Synchronization Mode is set to Incremental in 2. JSON: JSON message format, which is easy to interpret but takes up more space. JSON-C: A data format that is compatible with multiple batch and stream computing frameworks. For details, see Kafka Message Format.
   Synchronization Object	The left pane displays the source database objects, and the right pane displays the selected objects. You can select Tables or Databases for Synchronization Object as required. If the synchronization objects in source and destination databases have different names, you can map the source object name to the destination one. For details, see Changing Object Names (Mapping Object Names). 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 Process Data page, select the columns to be processed.
   • If data processing is not required, click Next.
   • If you need to process columns, set processing rules by referring to Processing Data.

6. 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.

7. 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 10 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.

8. 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.