From GaussDB(for MySQL) to Kafka

Supported Source and Destination Databases

Prerequisites

• You have logged in to the DRS console.
• Your account balance is greater than or equal to $0 USD.
• For details about the DB types and versions supported by real-time synchronization, see Supported Databases.
• If a subaccount is used to create a DRS task, ensure that an agency has been added. To create an agency, see Agency Management.

Suggestions

• When a task is being started or in the full synchronization phase, do not perform DDL operations on the source database. Otherwise, the task may be abnormal.
• To keep data consistency before and after the synchronization, ensure that no data is written to the destination database during the synchronization.

• 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 you have to synchronize data during peak hours, you can select Yes for Flow Control to adjust the synchronization speed.
  • 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.
• For more information about the impact of DRS on databases, see What Is the Impact of DRS on Source and Destination Databases?

Precautions

Before creating a synchronization task, read the following notes:

• You are advised to create an independent database account for DRS task connection to prevent task failures caused by database account password modification.
• After changing the account passwords for the source or destination databases, modify the connection information in the DRS task as soon as possible to prevent automatic retry after a task failure. Automatic retry will lock the database accounts.

Procedure

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

     Table 3 Task and recipient description

     Parameter	Description
     Region	The region where the synchronization instance is deployed. You can change the region.
     Project	The project corresponds to the current region and can be changed.
     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
     Figure 2 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: Public network, VPC, VPN or Direct Connect
     Instance Type	DRS instance type. The value can be Single or Primary/Standby. Primary/Standby: This architecture provides HA, improving the reliability of DRS instances. After a primary/standby instance is created, DRS creates two subtasks, each running on the primary and standby nodes. If the subtask on the primary node fails, DRS automatically starts the subtask on the standby node to continue the synchronization. Single: The single-node deployment architecture is used, which is cost-effective. This option is available only in specific scenarios. For details, see Performing a Primary/Standby Switchover.
     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 Subnet 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 ensure that there are available IP addresses. 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.
     AZ	This parameter is available only when you select primary/standby for Instance Type. It indicates the AZ where the DRS instance is created. If the source or destination database is in the same AZ as the DRS instance, you can get better performance. If Instance Type is set to primary/standby, you can specify Primary AZ and Standby AZ. Figure 3 AZ

   • DRS instance specifications
     Figure 4 Specifications
     

     Table 5 Specifications

     Parameter	Description
     Specifications	DRS instance specifications. Different specifications have different performance upper limits. For details, see Real-Time Synchronization. NOTE: Currently, DRS supports specification upgrade only in MySQL-to-MySQL synchronization tasks with single-node DRS instances configured. Task specifications cannot be downgraded. For details, see Changing Specifications.

   • Enterprise Projects and Tags
     Figure 5 Enterprise projects and tags
     

     Table 6 Enterprise Projects and Tags

     Parameter	Description
     Enterprise Project	An enterprise project you would like to use to centrally manage your Global Accelerator resources. Select an enterprise project from the drop-down list. The default project is default. For more information about enterprise project, see Enterprise Management User Guide. To customize an enterprise project, click Enterprise in the upper right corner of the console. The Enterprise Management page is displayed. For details, see Creating an Enterprise Project in Enterprise Management User Guide.
     Tags	This setting is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 10 tags. After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.

   

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

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.
   Figure 6 Source database information
   

   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.

   

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

   Figure 7 Destination database information
   

   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.
   Figure 8 Synchronization mode
   

   Table 9 Synchronization Object

   Parameter	Description
   Flow Control	You can choose whether to control the flow. Yes You can customize the maximum migration speed. 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 All day. A maximum of three 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. Figure 9 Flow control 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.
   Start Point	This option is available if you select Incremental in 2. The logs of the source database are obtained from the start point during an incremental synchronization. Run show master status to obtain the source database position and set File, Position, and Executed_Gtid_Set as prompted.
   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 partition 0, strong consistency can be obtained but write performance is impacted. 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 MySQL to Kafka. Avro refers to binary encoded format. This option is available 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, Import object file, 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 Mapping Object Names. For details about how to import an object file, see Importing Synchronization Objects. 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 the object name contains spaces, the spaces before and after the object name are not displayed. If there are multiple spaces between the object name and 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. This function is available when Synchronization Mode is set to Incremental in 2.
   • If data processing is not required, click Next.
   • If you need to process columns, set processing rules by referring to Processing Data.
   Figure 10 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.

     For details about how to handle check failures, see Checking Whether the Source Database Is Connected in Data Replication Service User Guide.

   • If all check items are successful, click Next.
     Figure 11 Pre-check
     
     

     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 Notification, SMN Topic, Synchronization Delay Threshold, and Stop Abnormal Tasks After, confirm that the configured information is correct, select the check box before the agreement, and click Submit to submit the task.
   Figure 12 Task startup settings
   

   Table 10 Task startup settings

   Parameter	Description
   Started 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	SMN topic. This parameter is optional. If an exception occurs during synchronization, the system will send a notification to the specified recipients.
   SMN Topic	This parameter is available only after you enable Send Notifications and create a topic on the SMN console and add a subscriber. For details, see Simple Message Notification User Guide.
   Synchronization Delay Threshold	During an incremental synchronization, a synchronization delay indicates a time difference (in seconds) of synchronization between the source and destination database. If the synchronization delay exceeds the threshold you specify, DRS will send alarms to the specified recipients. The value ranges from 0 to 3,600. To avoid repeated alarms caused by the fluctuation of delay, an alarm is sent only after the delay has exceeded the threshold for six minutes. NOTE: If the delay threshold is set to 0, no notifications will be sent to the recipient. In the early stages of an incremental synchronization, the synchronization delay is long because a large quantity of data is awaiting synchronization. In this case, no notifications will be sent. Before setting the delay threshold, enable Send Notification.
   Stop Abnormal Tasks After	Number of days after which an abnormal task is automatically stopped. The value must range from 14 to 100. The default value is 14. NOTE: Tasks in the abnormal state are still charged. If tasks remain in the abnormal state for a long time, they cannot be resumed. Abnormal tasks run longer than the period you set (unit: day) will automatically stop to avoid unnecessary fees.

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, and the task status remains unchanged. When you restart the task configuration, DRS applies for resources again.