From MySQL to Kafka

DMS for Kafka

Supported Source and Destination Databases

Table 1 Supported databases

Source DB

Destination DB
  • RDS for MySQL
  • Kafka
  • DMS for Kafka

Prerequisites

Suggestions

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, 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 or later, 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
  • If the data types are incompatible, the synchronization may fail.
  • If the source DB instance is an RDS MySQL instance, tables encrypted using Transparent Data Encryption (TDE) cannot be synchronized.
  • A real-time synchronization task may fail due to the change of the username and password of the source database. You need to rectify the information and then retry the synchronization task on the DRS console. Generally, you are advised not to modify the preceding information during synchronization.
  • If the source database port is changed during data synchronization, the synchronization task fails. If the destination database port is wrong, DRS automatically changes the port to the correct one, and then you need to retry the synchronization task. Generally, do not modify the port number during synchronization.
  • If a real-time synchronization task fails as the IP address is changed, the system automatically changes the IP address to the correct one. Then, you need to retry the task to continue the synchronization. Therefore, changing the IP address is not recommended.
  • 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.
  • The source database does not support point-in-time recovery (PITR).
  • Resumable upload is supported, but data may be repeatedly inserted into a table that does not have a primary key.
  • 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.
  • Data inconsistency may occur when the MyISAM table is modified during synchronization.
  • During synchronization of table-level objects, renaming tables is not recommended.
  • Set the expire_log_day parameter to a proper value to ensure that the binlog does not expire before data transfer resumes. This ensures that services can be recovered after interruption.

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

    Select Out of the cloud.

    Source DB Engine

    Select 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

    Source DB Instance

    The RDS 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
    • 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.

    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

    DB Instance Name

    The RDS DB instance selected during synchronization task creation. 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.

    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

    Synchronize DML

    Select the DML operations to be synchronized. By default, all DML operations are selected.

    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

    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 you select Partition 0, only automatically created topics can be synchronized.
    • 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.

    • 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 or Databases 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.
    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.

    • 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.

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

Parent topic: Out of the Cloud