From MySQL to Kafka

Supported Source and Destination Databases

Table 1 Supported databases

Source DB

Destination DB

  • On-premises MySQL databases

  • MySQL databases on an ECS

  • Kafka

  • DMS for Kafka

Prerequisites

  • You have logged in to the DRS console.

  • For details about the DB types and versions supported by real-time synchronization, see Real-Time Synchronization.

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

Before creating a synchronization task, read the following notes:

Table 2 Precautions

Type

Restrictions

Database permissions

  • The source database user must have the following permissions: SELECT, SHOW VIEW, EVENT, LOCK TABLES, REPLICATION SLAVE, REPLICATION CLIENT, and RELOAD.

Synchronization object

  • The table data can be synchronized.

  • Tables with storage engine different to MyISAM and InnoDB cannot be synchronized.

Source database

  • During the incremental synchronization, the binlog of the source MySQL database must be enabled and use the row-based format.

  • If the storage space is sufficient, store the source database binlog for as long as possible. The recommended retention period is three days.

  • If the expire_logs_days value of the source database is set to 0, the synchronization may fail.

  • Enable GTID for the source database. If GTID is not enabled for the source database, primary/standby switchover is not supported. DRS tasks will be interrupted and cannot be restored during a switchover.

  • During an incremental synchronization, the server_id value of the MySQL source database must be set. If the source database version is MySQL 5.6 or earlier, the server_id value ranges from 2 to 4294967296. If the source database is MySQL 5.7, the server_id value ranges from 1 to 4294967296.

  • The database and table names in the source database cannot contain non-ASCII characters, or special characters '<`>/\

Destination database

  • The destination database is a Kafka database.

Precautions

  • Objects that have dependencies must be synchronized at the same time to avoid synchronization failure. Common dependencies: tables referenced by views, views referenced by views, views and tables referenced by stored procedures/functions/triggers, and tables referenced by primary and foreign keys

  • Cascade operations cannot be performed on tables with foreign keys. If the foreign key index of a table is a common index, the table structure may fail to be created. You are advised to use a unique index.

  • Binlogs cannot be forcibly deleted. Otherwise, the synchronization task fails.

  • The source database does not support the reset master or reset master to command, which may cause DRS task failures or data inconsistency.

  • If the source MySQL database does not support TLS 1.2 or is a self-built database of an earlier version (earlier than 5.6.46 or between 5.7 and 5.7.28), you need to submit an O&M application for testing the SSL connection.

  • During the synchronization, do not delete or change the username, password, or permission of the source database, or change the port of the destination database.

  • Data inconsistency may occur when the MyISAM table is modified during synchronization.

  • During synchronization of table-level objects, renaming tables is not recommended.

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 Next.

    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 !=<>'&"\

    Table 4 Synchronization instance settings

    Parameter

    Description

    Data Flow

    Choose Self-built to self-built.

    Source DB Engine

    Select 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

    AZ

    Select the AZ where you want to create the DRS instance. Selecting the one housing the source or destination database can provide better performance.

    If Instance Type is set to primary/standby, you can specify Primary AZ and Standby AZ.

    VPC

    Select an available VPC.

    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.

    Security Group

    Select a security group. You can use security group rules to allow or deny access to the instance.

    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.

    Tags

    • This setting 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 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.

    Table 5 Source database settings

    Parameter

    Description

    IP Address or Domain Name

    The IP address or domain name of the source database.

    Port

    The port of the source database. Range: 1 - 65535

    Database Username

    The username for accessing the source database.

    Database Password

    The password for the database username.

    SSL Connection

    SSL encrypts the connections between the source and destination databases. If SSL is enabled, upload the SSL CA root certificate.

    Note

    • The maximum size of a single certificate file that can be uploaded is 500 KB.

    • If the SSL certificate is not used, your data may be at risk.

    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 6 Source database information

    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 7 Synchronization Object

    Parameter

    Description

    Topic Synchronization Policy

    Topic synchronization policy. The options are as follows:

    • Select A specified topic if the data volume of the source database is small.

    • Select Auto-generated topics if each table contains a lot of data. Then, the system automatically generates a topic for each table.

    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

    Topic name format. This parameter is available when Topic Synchronization Policy is set to Auto-generated topics.

    Only variables database and tablename are supported. The other characters must be constants. Replace $database$ with the database name and $tablename$ with the table name.

    For example, if this parameter is set to $database$-$tablename$ and the database name is db1, and the table name is tab1, the topic name is db1-tab1. If DDL statements are synchronized, $tablename$ is empty and the topic name is db1.

    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. This prevents data from being written to the same partition, and consumers can obtain data from different partitions concurrently.

    Data Format in Kafka

    Select the data format to be delivered from MySQL to Kafka.

    • 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

    Available options: Tables and Databases.

    • 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.

  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, confirm that the configured information is correct, and click Submit to submit the task.

    Table 8 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.

  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 image1 in the upper-right corner to view the latest task status.